Semeru

Photo of this volcano
Google Earth icon
  Google Earth Placemark
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 8.108°S
  • 112.92°E

  • 3676 m
    12057 ft

  • 263300
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Weekly Report: 30 April-6 May 2014


PVMBG reported that during 1 March-27 April white-and-gray plumes rose 100-400 m above Semeru’s Jongring Seloko crater and drifted W; during April eight “eruption” plumes rose 300-500 m. On 26 April at 1852 and 1934, and on 27 April at 0500, incandescent rockslides from the lava dome traveled as far as 300 m down the S flank. As of 28 April the Alert Level remained at 2 (on a scale of 1-4) and the public was reminded not to approach the crater within a 4-km radius.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


Most Recent Bulletin Report: April 2012 (BGVN 37:04)


Increased seismicity with lava flows and pyroclastic flows during February-April 2012

Semeru is one of the most active volcanoes worldwide and is of special concern because the drainage area is heavily populated. The volcano has a steep canyon that extends from the summit to the SE, which has funneled pyroclastic flows and lahars into populated areas. The decades-long seismicity from Semeru has typically included mildly explosive Strombolian style eruptions, earthquakes and tremor, ash plumes, and occasional pyroclastic flows (BGVN 32:03, 34:05, and 35:08). See the location of Semeru with respect to the regional setting in figure 17.

Figure 17. Index map of Semeru (red triangle) with respect to other Holocene regional volcanoes (black triangles). Courtesy of GVCHM and VDAP.

According to reporting by the Center of Volcanology and Geological Hazard Mitigation (CVGHM) and the USGS Volcano Disaster Assistance Program (VDAP), six large explosions between 1981 and 2002 resulted in many fatalities. They noted that since 1995, pyroclastic flows have been restricted to S drainages such as Kali Kembar; however, a small proportion of recent flows have entered the headwaters of Kali Koboan on the SE, which leads to heavily populated areas, including Sumberrejo and Candipuro (figure 18). This report discusses activity between February 2010 (the end of the previous report) and 2 May 2012.

Figure 18. 2010 map of Semeru and adjacent area, showing drainage channels from the summit and nearby population centers. Note the location of the 2012 lava flows just S and SE of the volcano. The area around the SE quadrant is heavily populated with a Volcano Population Index (VPI10) of 7,000. In previous eruptions, lahars reached as far as 30 km from the summit. Should similar lahars occur in the future, as many as 150,000 more inhabitants along major drainages could be affected. Based in part on a summary of activity by CVGHM and VDAP. Modified from Siswowidjoyo and others (1997) and Thouret and others (2007); VPI10 was calulated using LandScan 2010.

On 4 November 2010, CVGHM reported that from August to October 2010 seismic activity at Semeru had increased, and “smoke” and occasional gas plumes rose 400-500 m above the crater. During September incandescent avalanches traveled 400 m SE into the Besuk Kembar drainage on three occasions. Incandescence from the crater was observed in October. Incandescent avalanches traveled 600 m into Besuk Kembar on 2 November. Two days later, they reached 4 km into the Besuk Kembar and Besuk Bang (S) drainages (figure 18). CVGHM noted that the lava dome in the Jonggring Saloko crater was growing. The Alert Level remained at 2 (on a scale of 1-4).

According to the Darwin Volcanic Ash Advisory Centre (VAAC), during 18-19 November 2010, ash plumes rose to an altitude of 4.6 km and drifted 75-110 km N and NW. Sulfur dioxide gas was detected 75 km SW.

According to Volcano Discovery, the group observed 2-3 small-to-medium ash explosions per day during a photo expedition in May 2011, but noted that activity had increased during the past weeks.

In an account posted online by Volcano Discovery on 15 September 2011, the group visited the volcano and noted that an active lava dome was growing inside the crater and that 3-4 eruptions occurred daily. They inferred that the size and frequency of the eruptions had apparently increased in the past days (figure 19).

Figure 19. Photo of Semeru’s crater on 1 September 2011, with a lava dome. Courtesy of Volcano Discovery.

CVGHM reported that on 29 December 2011, both earthquakes and tremor increased, and dense white-and-gray plumes rose as high as 600 m above the active crater. During January 2012, crater incandescence was observed, and avalanches carried incandescent material 200-400 m away from the crater. According to a 4 January 2012 article in the Jakara Globe, a government official indicated that authorities had closed the trail to the peak of Semeru because of heavy rain and an increased danger of landslides.

On 2 February 2012 a large explosion was reported and incandescent material fell up to 2.5 km from the crater. Tables 20 and 21 indicate the types and numbers of earthquakes and other seismic events reported by CVGHM for February to April 2012. Based on the increased seismic activity and visual observations, CVGHM raised the Alert Level from 2 to 3 on 2 February 2012.

Table 20. Types and numbers of earthquakes and plumes observed at Semeru during February-April 2012. Key to seismic signals variously classified as follows: LD, long-distance volcanic earthquake; Erup, eruptive; Expl, explosive; HTr, harmonic tremor; and PF, pyroclastic flow; “-”, either none detected or data not provided. Courtesy of CVGHM.

Month (2012)    Deep    Shallow    LD    Local    Erup    Expl    HTr    PFFebruary         4         1       61      -       80     2336    116    430March            17        5       60      23      -      1665    610    40April            7         2       44      -       -      3447    66     4

Table 21. Observed Semeru plumes during February-April 2012. Data from CVGHM. (The only other plume noted by the Darwin VAAC between February 2010 and May 2012 was on 18-19 November 2010; this plume was noted earlier in the text). Courtesy of CVGHM.

Month          Number of       Plume height(2012)      observed plumes    above craterFebruary          22            100-500 mMarch             9             100-400 mApril             155           100-500 m

CVGHM reported that during 1-29 February 2012 multiple pyroclastic flows from Semeru traveled 500 and 2,500 m into the Besuk Kembar and Besuk Kobokan rivers (on the S flank), respectively. Government officials set up an exclusion zone on the SE flank where pyroclastic flows had occurred.

During 1 February-30 April 2012, dense gray-to-white plumes rose 100-500 m above Jongring Seloko crater and drifted W and N. Incandescence was visible up to 50 m above the crater during 1 February-31 March. Seismicity decreased toward the end of April, although the lava dome grew that month.

According to a news account (People’s Daily Online) on 1 March 2012, seismic activity had increased from 28 to 38 tremors per day. According to the news account, Dr. Surono, head of CVGHM, stated that the volcano was erupting daily, emitting ash plumes, and tremor occurred every 15-30 minutes. He also noted that the volcanic dome was increasing in size.

According to Volcano Discovery, an expedition leader visiting Semeru observed frequent explosions every few minutes on 27 March 2012, with many powerful enough to eject glowing bombs that produced small glowing avalanches down the S flank.

According to CVGHM and VDAP, a new lava dome started to extrude in late 2011 directly over a dome formed in 2010. The new dome probably will not completely fill the summit crater because it is being drained by two new lava flows, both flowing SE. The longer of the two lava flows extended about 1.9 km from the summit vent. Pyroclastic flows are being generated by collapse of the steep termini of the lava flows, and their deposits extend to 3.2 km from the summit, i.e. 0.7 km from the front shown in figure 18. In addition, the collapsing lava flow fronts are resulting in high levels of avalanche and rockfall activity. According to CVGHM and VDAP, the closest villages in the highest-risk areas on the S and SE flanks are about 10 km from the summit.

On 2 May 2012 CVGHM lowered the Alert Level to 2, but reminded the public not to approach the crater within a 4-km radius.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Volcano Disaster Assistance Program (VDAP), US Geological Survey (USGS), 1300 SE Cardinal Court, Bldg. 10, Suite 100, Vancouver, WA 98683; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac); Jakarta Globe (URL: http://www.thejakartaglobe.com); People’s Daily Online (URL: english.peopledaily.com; Volcano Discovery (URL: http://mobile.volcanodiscovery.com).

Index of Weekly Reports


2014: April
2013: October
2012: February | May
2010: February | November
2009: March | July
2008: April | May | June | July | August | September | October
2007: February | May | June | August | September | October
2006: March | April | May | June | July | August | September | October | November | December
2005: May
2004: April | May | June | July | August
2003: January | February | March | April | May | July | August | September | October | December
2002: March | April | June | July | August | September | December
2001: February | March | April | May | July | September | October
2000: December

Weekly Reports


30 April-6 May 2014

PVMBG reported that during 1 March-27 April white-and-gray plumes rose 100-400 m above Semeru’s Jongring Seloko crater and drifted W; during April eight “eruption” plumes rose 300-500 m. On 26 April at 1852 and 1934, and on 27 April at 0500, incandescent rockslides from the lava dome traveled as far as 300 m down the S flank. As of 28 April the Alert Level remained at 2 (on a scale of 1-4) and the public was reminded not to approach the crater within a 4-km radius.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 October-22 October 2013

The Darwin VAAC reported that on 18 October a pilot saw a low-level ash plume from Semeru. Ash was not identified in satellite images.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 May-8 May 2012

CVGHM reported that during 1-29 February multiple pyroclastic flows from Semeru traveled 500 and 2,500 m into the Besuk Kembar and Besuk Kobokan rivers (on the S flank), respectively. During 1 February-30 April dense gray-to-white plumes rose 100-500 m above Jongring Seloko crater and drifted W and N. Incandescence was visible up to 50 m above the crater during 1 February-31 March. Seismicity decreased from March to April. Observations indicated that the lava dome grew in April. On 2 May CVGHM lowered the Alert Level to 2 (on a scale of 1-4) and reminded the public not to approach the crater within a 4-km radius.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


1 February-7 February 2012

On 3 February, CVGHM reported that from 29 December 2011 to 2 February 2012 seismicity increased at Semeru, and dense white and gray plumes rose as high as 600 m above the Jonggring Seloko crater. During the month of January crater incandescence was observed and avalanches carried incandescent material 200-400 m away from the crater. On 2 February a large explosion was reported and incandescent material was ejected 2.5 km from the crater. Based on the seismic activity and visual observations, CVGHM raised the Alert Level from 2 to 3 (on a scale of 1-4) on 2 February.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


17 November-23 November 2010

Based on analysis of satellite imagery, the Darwin VAAC reported that during 18-19 November ash plumes from Semeru rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted 75-110 N and NW. Sulfur dioxide gas concentrations were detected 75 km SW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


3 November-9 November 2010

On 4 November, CVGHM reported that from August to October seismic activity at Semeru had increased, and "smoke" and occasional gas plumes rose 400-500 m above the crater. During September incandescent avalanches traveled 400 m SE into the Besuk Kembar drainage on three occasions. Incandescence from the crater was observed in October. Incandescent avalanches traveled 600 m E into Besuk Kembar on 2 November and 4 km into the Besuk Kembar and Besuk Bang (SSE) drainages on 4 November. CVGHM noted that the lava dome in the Jonggring Saloko crater was growing. The Alert Level remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


24 February-2 March 2010

On 1 March, CVGHM reported that although inclement weather often prevented observations of Semeru during November 2009-February 2010, "smoke" was often seen rising 50-500 m above the Jonggring Seloko crater. During 25-28 February, incandescent rock avalanches traveled as far as 750 m from the crater. The Alert Level remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


15 July-21 July 2009

CVGHM reported that on 15 March an eruption from Semeru produced a white-and-gray plume that rose 600 m above the crater. White plumes and ash eruptions gradually ceased and seismicity decreased. From 5 May until the end of June, fog prevented visual observations. On 16 July, the Alert Level was lowered to 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


11 March-17 March 2009

Based on information from CVGHM, the Darwin VAAC reported that on 12 March an eruption from Semeru produced a plume to an altitude of 4.6 km (15,000 ft) a.s.l. Ash was not identified on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


4 March-10 March 2009

On 6 March, CVGHM reported that an ash eruption from Semeru was characterized by increased seismicity and booming sounds from the Jonggring Seloko crater; fog prevented visual observations. The Alert Level was raised to 3 (on a scale of 1-4). Based on analysis of satellite imagery, the Darwin VAAC reported that on 7 March a possible plume rose to altitudes of 3.7-4.3 km (12,000-14,000 ft) a.s.l.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


22 October-28 October 2008

Based on analysis of satellite imagery, the Darwin VAAC reported that on 22 October a plume from Semeru rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted WSW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


10 September-16 September 2008

Based on analysis of satellite imagery, the Darwin VAAC reported that on 10 September a plume from Semeru rose to an altitude of 4.3 km (14,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


3 September-9 September 2008

Based on analysis of satellite imagery, the Darwin VAAC reported that on 9 September ash plumes from Semeru rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted SSW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


27 August-2 September 2008

Based on pilot observations, the Darwin VAAC reported that a low-level plume from Semeru was present on 28 August. A pilot reported that an ash plume rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted SW on 31 August.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


20 August-26 August 2008

Based on pilot reports and observations of satellite imagery, the Darwin VAAC reported that during 21-22 August ash plumes from Semeru rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


6 August-12 August 2008

Based on information from CVGHM, the Darwin VAAC reported that on 7 August ash plumes from Semeru rose to an altitude of 4.3 km (14,100 ft) a.s.l. and that incandescent material was ejected from the crater. CVGHM indicated that the activity was normal; the Alert Level remained at 2 (on a scale of 1-4).

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


30 July-5 August 2008

CVGHM reported on 5 August that ash plumes from Semeru rose to altitudes of 4-4.3 km (13,100-14,100 ft) a.s.l. and were occasionally accompanied by ejected incandescent tephra. Based on visual observations and instrumental data, the Alert level remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


23 July-29 July 2008

The Darwin VAAC reported that on 27 July an ash plume at an altitude of 4.3 km (14,000 ft) a.s.l. was spotted by a pilot in the vicinity of Semeru. Ash was not identified on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 July-8 July 2008

Based on pilot reports and observations of satellite imagery, the Darwin VAAC reported that during 7-9 July ash plumes from Semeru rose to altitudes of 4.9-7.6 km (16,000-25,000 ft) a.s.l. and drifted SSW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


4 June-10 June 2008

CVGHM reported that pyroclastic flows and rockfall avalanches from Semeru detected by the seismic network declined in frequency during 22 May-3 June. On 22 May, four pyroclastic flows traveled a maximum distance of 2.5 km from the active crater. Visual observations of smaller rockfalls detected during the rest of the reporting period were inhibited by fog, but were observed to travel 200-300 m from the active crater. Based on visual observations and the decline in seismic activity, CVGHM lowered the Alert Level to 2 (on a scale of 1-4) on 5 June.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


21 May-27 May 2008

CVGHM reported that during 15, 17-19, and 21 May, ash plumes rose from Semeru's summit, rockfalls descended the flanks, and multiple pyroclastic flows traveled 500-3000 m from the active crater. On 21 May, incandescent material was propelled from the summit. Based on visual observations and increased seismicity, CVGHM raised the Alert Level from 2 to 3 (on a scale of 1-4). The community was advised not to go within 4 km from the summit on the SE flank.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 April-22 April 2008

Based on pilot observations, the Darwin VAAC reported that a plume from Semeru rose vertically to an altitude of 6.1 km (20,000 ft) a.s.l. on 21 April.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


31 October-6 November 2007

Based on reports from CVGHM, the Darwin VAAC reported that an unconfirmed eruption from Semeru was heard from 17 km away on 31 October. An eruption plume was not detected on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


19 September-25 September 2007

Based on a pilot observation, the Darwin VAAC reported that an ash plume from Semeru rose to an altitude of 7.3 km (24,000 ft) a.s.l. on 22 September. Ash was not detected on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


1 August-7 August 2007

Based on a pilot observation, the Darwin VAAC reported that an ash plume, possibly from Semeru, rose to an altitude of 6.1 km (20,000 ft) a.s.l. on 6 August. Ash was not detected on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


20 June-26 June 2007

Based on visual observations, CVGHM reported that during 18-25 June multiple ash explosions from Semeru produced plumes that rose to an altitude of 4.2 km (13,800 ft) a.s.l. The Alert Level remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


6 June-12 June 2007

The Darwin VAAC reported that a pilot observed an ash plume over the summit of Semeru on 12 June. Ash was not detected on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


23 May-29 May 2007

Based on a pilot report and information from CVGHM, the Darwin VAAC reported diffuse ash plumes from Semeru at an altitude of 4.6 (15,000 ft) a.s.l. on 25 May. The plumes drifted W. Ash was not detected on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 May-8 May 2007

Based on satellite imagery and information from CVGHM, the Darwin VAAC reported diffuse ash plumes from Semeru at an altitude of 4.6 (15,000 ft) a.s.l. during 3-5 May. The plumes drifted SW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


7 February-13 February 2007

Based on a news report, eruption plumes from Semeru drifted E on 10 and 11 February. Ashfall was reported from areas including the town of Lumajang, about 35 km E.

Source: Agence France-Presse (AFP)


20 December-26 December 2006

The Darwin VAAC reported that a plume from Semeru was visible on satellite imagery on 21 December at an altitude of 4.3 (14,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


22 November-28 November 2006

Based on a pilot report, the Darwin VAAC reported that on 22 November an ash plume from Semeru reached 7.6 km (25,000 ft) a.s.l. and drifted S. On 24 November, CVGHM reported an eruption plume to an altitude of 4.4 km (14,000 ft) a.s.l. Incandescent material fell to the ground in all directions within a 200 m radius from the center of the plume.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC); Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


25 October-31 October 2006

Based on a pilot report, the Darwin VAAC reported that on 25 and 26 October, an eruption plume from Semeru reached 7.6 km (25,000 ft) a.s.l. and drifted W. On 30 October, ash-and-steam emissions were detected on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


18 October-24 October 2006

Based on a pilot report, the Darwin VAAC reported that on 18 October, an eruption plume from Semeru reached 4.6 km (15,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


20 September-26 September 2006

Based on satellite imagery, the Darwin VAAC issued multiple aviation ash advisories for Semeru during 20-21 September. Plumes were initially reported to be near 11 km (36,000 ft) a.s.l. and drifting SW. The later reports noted a plume at 4.9 km (16,000 ft) a.s.l. extending about 90 km W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


13 September-19 September 2006

Based on pilot reports, the Darwin VAAC reported that an eruption plume from Semeru reached 4.3 km (14,000 ft) a.s.l. and drifted W on 15 September.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


23 August-29 August 2006

According to the Darwin VAAC, ash plumes from Semeru were visible on satellite imagery on 25 August.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 August-8 August 2006

Eruption plumes from Semeru were visible on satellite imagery on 2 August. They reached a maximum altitude of 5.2 km (17,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


26 July-1 August 2006

According to the Darwin VAAC, on 24-25 and 31 July small plumes from Semeru were visible on satellite imagery and reached unknown altitudes.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


19 July-25 July 2006

Eruption plumes from Semeru were visible on satellite imagery on 18, 21, and 24 July and reached a maximum altitude of 4.3 km (14,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


12 July-18 July 2006

Eruption plumes from Semeru were visible on satellite imagery on 14 July drifting SE at unknown altitudes. On 17 July plumes reached altitudes of 4.3 km (14,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


5 July-11 July 2006

According to the Darwin VAAC, an ash plume from Semeru reached a maximum altitude of 5.5 km (18,000 ft) a.s.l. on 10 July. The plume was visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


28 June-4 July 2006

According to the Darwin VAAC, on 29 June a small plume from Semeru that was visible on satellite imagery drifted SE at an unknown altitude.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


21 June-27 June 2006

Based on a pilot report, the Darwin VAAC reported that an ash plume from Semeru reached 5.5 km (18,000 ft) a.s.l. on 25 June.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


14 June-20 June 2006

According to the Darwin VAAC, a pilot reported that ash plumes from Semeru on 14 June reached altitudes of 6.1 km (20,000 ft) a.s.l. Small ash plumes were detected on satellite imagery on 15, 17, and 18 June.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


7 June-13 June 2006

According to the Darwin VAAC, satellite imagery showed small ash plumes from Semeru on 6 and 12 June and minor ash-and-steam plumes on 11 and 13 June, all at unknown altitudes.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


31 May-6 June 2006

According to the Darwin VAAC, a pilot reported multiple minor eruptions from Semeru on 4 June. Small ash plumes were detected on satellite imagery on 5-6 June.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


10 May-16 May 2006

An ash plume from Semeru at a height of 6.1 km (20,000 ft) a.s.l. was observed on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


19 April-25 April 2006

Based on information from a significant meteorological forecast (SIGMET), the Darwin VAAC reported that on 22 April an eruption at Semeru generated a plume that rose to ~4 km (13,000 ft) a.s.l. Ash was not visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


8 March-14 March 2006

Based on information from the Center of Volcanology and Geological Hazard Mitigation (CVGHM formerly DVGHM), the Darwin VAAC reported that "ash rain" from Semeru was reported near the volcano. Ash was not visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


25 May-31 May 2005

The Darwin VAAC received a report that a small plume was visible above Semeru's summit on 25 May. The Darwin VAAC received a report that a small plume was visible above Semeru's summit on 25 May.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


18 May-24 May 2005

Satellite imagery on 21 May showed a thin plume from Semeru at a height of ~4.6 km (~15,000 ft) a.s.l. extending to the S and later SSE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


25 August-31 August 2004

On 25 August, a thin plume emitted from Semeru was visible on satellite imagery extending WSW. No ash was visible on the satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


18 August-24 August 2004

On 24 August a thin plume emitted from Semeru was visible on satellite imagery extending to the WSW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


11 August-17 August 2004

A pilot reported to the Darwin VAAC that on 10 August ash from Semeru was at a height of ~6.1 km a.s.l. According to a news article, people were temporarily banned from climbing the volcano.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC); ABC News - Australian Broadcasting Corporation


4 August-10 August 2004

During 5-10 August, pilots reported to the Darwin VAAC that several ash clouds were emitted from Semeru. The highest rising cloud reached ~7.6 km a.s.l. Ash was not visible on satellite imagery. The Alert Level at Semeru was at 2 (on a scale of 1-4).

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


14 July-20 July 2004

A pilot reported an ash plume from Semeru on 18 July at a height of ~3 km a.s.l. drifting NW. No ash was visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


16 June-22 June 2004

Based on information from a pilot's report, the Darwin VAAC reported that on 18 June an ash cloud from Semeru was visible at a height of ~6 km a.s.l., extending ~40 km E. Ash was not visible on satellite imagery. The Darwin VAAC reported that DVGHM listed the volcano at Alert Level 2 (on a scale of 1-4).

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 June-8 June 2004

An ash plume from Semeru was reported on 4 June at ~4.5 km a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


19 May-25 May 2004

The Darwin VAAC reported that a thin ash plume from Semeru was visible on satellite imagery on 23 May around 0625. The plume reached a height of ~4.3 km a.s.l. and extended ~110 km SSE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


21 April-27 April 2004

The Darwin VAAC reported that an ash plume from Semeru was visible on satellite imagery on 21 April. The plume rose to ~4.6 km a.s.l. and drifted ESE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


14 April-20 April 2004

The Darwin VAAC reported that ash plumes from Semeru were visible in satellite imagery on 18 and 20 April. The plumes reached heights of ~4.5 km and extended ~90 km NW and ~75 km SSE, respectively.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


3 December-9 December 2003

Satellite imagery on 2 December at 1728 showed an ash plume from Semeru at ~4 km a.s.l. that extended ~55 km WSW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


29 October-4 November 2003

During October, ash explosions at Semeru continued to produce low-level plumes and seismicity was dominated by hundreds of explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


8 October-14 October 2003

During 1-28 September, volcanic activity at Semeru continued at relatively high levels. Several ash explosions produced plumes to 400-500 m above the volcano. Seismicity was dominated by as many as 735 explosion earthquakes per week. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


3 September-9 September 2003

An ash plume emitted from Semeru on 9 September rose to ~7.3 km a.s.l. and drifted S. Ash was not visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


20 August-26 August 2003

During 11-17 August, volcanic activity at Semeru continued at relatively high levels. Explosions produced ash columns that rose to 400 m above the summit. Seismicity was dominated by 550 explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


13 August-19 August 2003

A faint ash plume from Semeru was visible on satellite imagery on 13 August, extending ~75 km E of the summit.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


6 August-12 August 2003

Thin ash plumes from Semeru were visible on satellite imagery on 8 and 9 August. On 9 August the plume extended ~40 km SW of the volcano.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


30 July-5 August 2003

Based on information from an aircraft report, the Darwin VAAC reported that an ash plume emitted from Semeru rose to ~4.5 km a.s.l. on 31 July at 1120. No ash was visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


16 July-22 July 2003

An ash cloud from Semeru was visible on satellite imagery on 21 July at 2316 extending ~75 km to the WSW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 July-8 July 2003

During 2-29 June, activity continued at high levels at Semeru. Several explosions occurred during the report period, with the highest ash plumes rising to a height of ~600 m. Seismicity was dominated by hundreds of explosion events per week. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


28 May-3 June 2003

Plumes emitted from Semeru were visible on satellite imagery at a height of ~6 km a.s.l. on 29 May at 0838 drifting NW, and on 2 June at 0625 drifting SSE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


21 May-27 May 2003

Volcanic and seismic activity at Semeru continued at relatively high levels during 12-18 May. Several small ash explosions rose to low levels above the summit. Seismicity was dominated by 730 explosion events. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 April-22 April 2003

During the week of 16-22 April, Semeru was continually active. A white-gray ash plume@ rose 400-500 m over the summit. Seismic signals interpreted as pyroclastic flows were recorded multiple times during the week. One pyroclastic flow on 18 April traveled into several local drainages, reaching lengths of ~2.5 and ~3.5 km.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


9 April-15 April 2003

Volcanic activity remained at relatively high levels at Semeru during 31 March to 6 April. "White-gray ash plumes" rose 400-600 m above the summit and seismicity was dominated by 738 explosion events. According to the Darwin VAAC, a pilot reported seeing ash ~2.5 km above Semeru on 15 April at 1038. No ash was visible on satellite imagery. The Alert Level at Semeru remained at 2 (on a scale of 1-4).

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


2 April-8 April 2003

Seismic and volcanic activity continued at relatively high levels at Semeru during 24-30 March, with "gray ash plumes" rising to low levels, pyroclastic-flow activity, and several explosions. On 27 March a pyroclastic flow travelled around 3,750 m toward Bang River. During the week, seismicity was dominated by 794 explosion events. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 March-1 April 2003

Seismic and volcanic activity continued at relatively high levels at Semeru during 17-23 March, with "gray ash plumes" rising 300-400 m above the summit, and several pyroclastic flows traveling toward Bang River to runout distances of around 500 m. Seismicity was dominated by 563 explosion events. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


19 March-25 March 2003

During 10-16 March at Semeru, "white-gray ash plumes" rose to low levels and several pyroclastic flows traveled 1.5-4 km down Bang River. Seismicity was dominated by 550 explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


12 March-18 March 2003

During 3-9 March, volcanism at Semeru remained at high levels. "White-gray ash plume[s]" rose to low levels above the summit and several "pyroclastic avalanches" traveled 200-2,000 m into Besuk Kembar River. Seismicity was dominated by 794 explosion earthquakes. The Alert Level at Semeru remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


5 March-11 March 2003

During 24 February to 2 March, volcanism at Semeru remained at high levels. "White-gray ash plumes" were observed rising 300-400 m above the summit. Seismicity was dominated by 629 explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


5 February-11 February 2003

During 3-9 February, volcanic activity remained at high levels at Semeru, with ash plumes rising 300-400 m above the summit. On 7 February a pyroclastic flow traveled 2-4 km into the Besuk Bang River. Seismicity during the report period was dominated by 777 explosion events and 14 pyroclastic flows were recorded. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


22 January-28 January 2003

During 13-26 January volcanic activity remained at relatively high levels at Semeru, with ash plumes rising 400-600 m above the summit. On 19 and 23-24 January incandescent lava avalanches traveled ~500 m down Besuk Kembar River. Semeru was at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


8 January-14 January 2003

Relatively high volcanic and seismic activity continued at Semeru during 1-12 January. Several explosions sent ash columns to 700 m above the crater. Lava avalanches sent material up to 750 m from the crater rim and a pyroclastic flow traveled 1.5 km E to the Besuk Kembar River. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


31 December-6 January 2003

Volcanic and seismic activity were relatively high at Semeru during 17-30 December. During the report period the most notable seismically recorded events were 1,085 explosions, 49 lava avalanches, 6 pyroclastic flows, and 3 floods/lahars. Explosions sent ash plumes to 400 m above Jonggring Seloko crater. On 25 December a pyroclastic flow traveled 2.5 km into the Besuk Kembar River. On 29 December during 1700-2015, a lahar traveled along the Besuk Kembar River relatively close to Supit village. Early that morning the residents of Supit were evacuated. On 30 December pyroclastic flows traveled 2 km toward the Besuk Kembar River at 0720, and at 1000 one traveled 4 km toward Supit village. The Alert Level at Semeru remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


24 December-30 December 2002

During 9-22 December, volcanic and seismic activity remained above normal levels at Semeru. Ash columns rose 400-500 m above the volcano, and lava avalanches and pyroclastic flows were seismically recorded. The Alert Level was at 2 (on a scale of 1-4). According to news articles, the emission of lava and hot gas caused authorities to ban all recreational activity at Semeru beginning on 22 December.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); News.com.au - News Limited; Channelnewsasia.com


18 September-24 September 2002

Ash clouds were observed at Semeru rising to ~7.6 a.s.l. on 22 September at 1453 and on 23 September at 1700. The September 23rd cloud drifted SW. Neither cloud was visible on satellite imagery due to meteorological clouds in the area.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


11 September-17 September 2002

On 8 September at 1947 an ash explosion at Semeru was accompanied by ejected incandescent material. The material traveled 150 m E to the upper portion of the Kembar River. During 2-8 September, seismicity was dominated by explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


21 August-27 August 2002

During 5-18 August, volcanic and seismic activity at Semeru remained at higher-than-normal levels. On 6 August a lava avalanche traveled ~750 m E toward Besuk Kembar River. Seismicity consisted of tectonic, explosion, and avalanche earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


31 July-6 August 2002

Activity at Semeru remained at a higher level than normal, but thick fog obscured the view. Seismicity increased compared to the previous week and was dominated by 744 explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


24 July-30 July 2002

When weather conditions were clear during 15-21 July, lava avalanches were observed traveling ~750 m from Semeru's crater rim E toward Besuk Kembar River. Explosions produced ash plumes reaching 300-500 m above the crater. Seismicity was dominated by 670 explosion earthquakes, while the number of other types of earthquakes decreased in comparison to the previous week. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


17 July-23 July 2002

When weather conditions were clear during 8-14 July, lava avalanches were sometimes observed traveling 750 m from Semeru's crater rim E toward Besuk Kembar River. Low-level ash plumes rose above the crater. Seismicity was dominated by 898 explosion earthquakes, while the number of other types of earthquakes decreased. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


10 July-16 July 2002

When weather conditions were clear during 1-7 July, lava avalanches were sometimes observed traveling 750 m from Semeru's crater rim E toward Besuk Kembar River. Seismicity decreased in comparison to the previous week. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 June-2 July 2002

During 17-23 June, seismic and volcanic activity were higher than normal at Semeru. Lava avalanches were observed traveling 750 m E to the Besuk Kembar River. Seismicity included 670 explosion events. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


24 April-30 April 2002

Volcanic activity remained higher than normal at Semeru during 15-21 April. A small plume rose ~400 m above the summit and a "red reflection" was occasionally visible 25 m above the crater rim. Lava avalanches traveled 750 m to the E down Besuk Kembar River. The volcano remained at Alert Level 2.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


20 March-26 March 2002

Volcanic and seismic activity remained high at Semeru during 11-17 March. Observations on 12, 14, and 17 March revealed that a gray plume rose 300-400 m above the summit. Seismicity was dominated by 444 explosion earthquakes, and there was a decrease in the number of tectonic and deep volcanic earthquakes in comparison to the previous week. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


6 March-12 March 2002

An increase in volcanic and seismic activity at Semeru during 3-10 March led VSI to raise the Alert Level from 1 to 2 (on a scale of 1-4). On 8 March observers saw an emission rise ~400 m above the volcano, and two pyroclastic flows travel S as far as 2.5 km down the Kembar River. During the report period there was an increase in tectonic and volcanic earthquakes in comparison to the previous week.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


3 October-9 October 2001

VSI reported that as of 5 October volcanic activity at Semeru was at normal levels, with a plume rising ~600 m above the volcano.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 September-2 October 2001

According to the Darwin VAAC, a pilot reported observing an ash plume rising 1-4 km above Semeru on 1 October at 1457. No ash was visible in satellite imagery, possibly due to low-level meteorological clouds obscuring the plume.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


18 July-24 July 2001

Seismic data revealed that during 9-15 July activity was higher than in the previous week. During this period 687 explosion events were recorded, as well as 57 avalanches, and 11 tectonic earthquakes. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


11 July-17 July 2001

Seismic data revealed that during 2-8 July the number of explosions and avalanche earthquakes at Semeru decreased in comparison to the previous week. The volcano was at Alert Level 2.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


4 July-10 July 2001

Based on information from pilot reports and the Meteorological and Geophysical Agency of Indonesia, the Darwin VAAC reported that on 8 July at 1503 a SE-drifting ash plume rose to ~2.5 km above the volcano. Ground based reports prior to the eruption revealed that each day during 18-24 June Semeru emitted ash to ~0.6 km above the volcano.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 May-8 May 2001

Volcanic activity increased at Semeru in comparison to the previous week. Seismographs recorded 759 explosion events (550 last week), 157 avalanche events, and four tectonic earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


25 April-1 May 2001

Volcanic activity increased at Semeru in comparison to the previous week, with an increase in explosion and deep volcanic earthquakes. Seismographs recorded 550 explosion events, 149 avalanche events, and ten tectonic earthquakes. Gas explosions rose up to 300 m above the volcano. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


18 April-24 April 2001

VSI reported that during 9-15 April activity at Semeru was higher than normal. Minor explosions that rose 300 m above the volcano were observed during clear weather. Seismographs recorded an increase in seismicity in comparison to the previous week, with 339 explosion events, 51 avalanche events, and three tectonic earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


11 April-17 April 2001

There was a significant increase in the number of earthquakes detected at Semeru during 2-9 April following a decrease in volcanic activity during the previous several weeks. Seismographs recorded 28 deep volcanic earthquakes, 305 explosion events, 248 avalanche events, and 3 tectonic earthquakes. Cloudy conditions prohibited visual observations. Semeru remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


4 April-10 April 2001

During 27 March-1 April, VSI personnel observed several lava avalanches that traveled to Kembar River valley as far as 750 m S of the summit. No seismic data were available because the seismometers broke on 24 March 2001. They were repaired on 1 April. Semeru is at hazard level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


21 March-27 March 2001

The summit of the volcano was covered by clouds during 12-18 March, but the seismic record showed increasing activity. Explosion and avalanche earthquakes still dominated seismicity and increased over the past week. There were 349 explosion earthquakes, an increase over the 303 detected during 6-12 March. The count of explosion earthquakes decreased to 259 the week of 19-26 March. Semeru is at hazard level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


28 February-6 March 2001

The VSI reported that a small steam plume rose ~100 m above Semeru's summit and that seismicity was dominated by 702 explosion earthquakes. In addition to the explosion earthquakes, three deep volcanic, 58 avalanche, and five tectonic earthquakes occurred. The volcano remained at Alert Level 2 (on a scale of 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


13 December-19 December 2000

The VSI reported that during 5-11 December fume from Jonggring Seloko crater located in the S sector of Semeru's summit rose up to 600 m above the crater. The seismic record was dominated by explosion earthquakes and the record showed that two pyroclastic flows occurred. The volcano remained at Alert Level 2 (ranging from 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


6 December-12 December 2000

On 11 December an air report to the Darwin VAAC stated that volcanic ash was observed near Semeru at an altitude of ~7.6 km a.s.l. The Darwin VAAC stated that the activity may have been associated with Semeru, which frequently erupts ash to ~4.5 km. Due to cloudy conditions, any low-level volcanic activity that was occurring at that time was not visible in satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


Index of Bulletin Reports


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

04/1972 (CSLP 27-72) Lava flows and eruption plume

05/1972 (CSLP 27-72) Review of recent activity since 1967

11/1976 (NSEB 01:14) Ejection of ash and nuées ardentes; lava dome growth

03/1977 (NSEB 02:03) Long-running eruption continues typical activity

01/1980 (SEAN 05:01) Dome growth and ash explosions decline

09/1980 (SEAN 05:09) Ash eruptions

02/1981 (SEAN 06:02) Ash emission and hot avalanches

03/1981 (SEAN 06:03) Nuées ardentes and lava avalanches; one killed, 272 evacuated

05/1981 (SEAN 06:05) Mudflow kills more than 250

08/1985 (SEAN 10:08) Two-year eruption continues

12/1985 (SEAN 10:12) Frequent explosions and lava extrusion throughout 1985

04/1986 (SEAN 11:04) Normal small Vulcanian explosions continue

05/1986 (SEAN 11:05) Explosions continue, nuée adente observed

06/1986 (SEAN 11:06) Continued small explosions

09/1986 (SEAN 11:09) Frequent summit Vulcanian explosions continue

11/1986 (SEAN 11:10) Vulcanian explosions continue

12/1986 (SEAN 11:12) Frequent summit explosions continue

02/1987 (SEAN 12:02) Minor explosions continue

03/1987 (SEAN 12:03) Normal Vulcanian explosions continue

04/1987 (SEAN 12:04) Continued small Vulcanian explosions

06/1987 (SEAN 12:06) Normal Vulcanian activity

07/1987 (SEAN 12:07) Glowing rockfall avalanches enter new drainages

08/1987 (SEAN 12:08) Vulcanian activity continues; nuées ardentes de avalanche

09/1987 (SEAN 12:09) Vulcanian activity continues

10/1987 (SEAN 12:10) Vulcanian activity continues

12/1987 (SEAN 12:12) Continued Vulcanian activity

02/1988 (SEAN 13:02) Continued Vulcanian activity

03/1988 (SEAN 13:03) Vulcanian activity continues; clouds to 7.5 km

04/1988 (SEAN 13:04) Vulcanian explosions continue in 21-year eruption

06/1988 (SEAN 13:06) Vulcanian activity continues

07/1988 (SEAN 13:07) Vulcanian activity persists

05/1989 (SEAN 14:05) Frequent lava avalanches and nuees ardentes

07/1989 (SEAN 14:07) Vulcanian explosions, lava avalanches, and nuées ardentes

07/1990 (BGVN 15:07) End to Vulcanian activity and dome growth; new collapse pit in crater

03/1991 (BGVN 16:03) Ash emissions; 400-m-long lava flow

04/1991 (BGVN 16:04) Continued explosions and seismicity

11/1991 (BGVN 16:11) More frequent explosions and tremor; lava avalanches

10/1992 (BGVN 17:10) Frequent explosions eject 1-km clouds; summit morphology described

01/1994 (BGVN 19:01) Lava avalanches and pyroclastic flows kill six people

07/1994 (BGVN 19:07) Small ash eruptions to 500 m above the summit

10/1994 (BGVN 19:10) Normal mild explosive activity in August; slow lava extrusion

03/1995 (BGVN 20:03) Ash eruptions, lava avalanches, and summit glow

07/1995 (BGVN 20:07) Hazard status raised; mid-July explosion earthquakes, pyroclastic flows

10/1995 (BGVN 20:10) Explosions and pyroclastic flows continue

01/1996 (BGVN 21:01) Explosions, pyroclastic flows, and lava avalanches continue

06/1996 (BGVN 21:06) Eruptions form ash plumes

09/1996 (BGVN 21:09) Intermittent pilot reports of eruptions from August to October

11/1996 (BGVN 21:11) A 2-km-long pyroclastic flow on 7 October; minor ashfall

06/1997 (BGVN 22:06) Pilots saw April-June ash at 3- to 7-km altitudes

08/1997 (BGVN 22:08) Frequent explosions and ash plumes; two climbers killed

10/1997 (BGVN 22:10) Ash plumes during October and November

05/1999 (BGVN 24:05) Mass wasting in March; ash eruptions continue; 9-km-high ash cloud in May

08/1999 (BGVN 24:08) Ash emissions and pyroclastic flows during June-September

09/1999 (BGVN 24:09) Short-lived Vulcanian explosions continuing from Jonggring Seloko Crat

07/2000 (BGVN 25:07) Ongoing eruptive activity; 27 July explosion causes injuries and two fatalities

08/2001 (BGVN 26:08) Continuous seismic activity, plumes to ~11.6 km

06/2002 (BGVN 27:06) Seismicity increases beginning in March 2002; Alert Level increased to 2

09/2002 (BGVN 27:09) Higher-than-normal seismic and explosive activity during June-September 2002

12/2002 (BGVN 27:12) Elevated explosive activity continues; evacuation on 30 December 2002

04/2003 (BGVN 28:04) Continued ash explosions, with frequent lava avalanches and pyroclastic flows

07/2003 (BGVN 28:07) Ash plumes, pyroclastic flows, and high seismicity continue through June

09/2003 (BGVN 28:09) Frequent ash explosions continue through September

10/2003 (BGVN 28:10) Frequent ash explosions continue through October

12/2003 (BGVN 28:12) November volcanism includes 70-90 explosions per day

06/2004 (BGVN 29:06) Persistent seismicity and ash plumes during April-June 2004

03/2007 (BGVN 32:03) Minor ash eruptions continue into February 2007

05/2009 (BGVN 34:05) Many ash plumes and some pyroclastic flows during February 2007-March 2009

08/2010 (BGVN 35:08) Incandescent rock avalanches travel 750 m, plumes reach 500 m above crater

04/2012 (BGVN 37:04) Increased seismicity with lava flows and pyroclastic flows during February-April 2012




Bulletin Reports

All information contained in these reports is preliminary and subject to change.


04/1972 (CSLP 27-72) Lava flows and eruption plume

Card 1382 (18 April 1972) Lava flows and eruption plume

"Mount Semeru . . . has shown signs of intensity lately. According to the Bureau of Volcanology, lava is flowing from the volcano toward the S and E. Smoke spewing out of the volcano is rising up to 1,500 m. In view of this development, the Geological Directorate in Bandung is conducting a close observation of the volcano."

Information Contacts: Djajadi Hadikusumo, Geological Survey of Indonesia.

05/1972 (CSLP 27-72) Review of recent activity since 1967

Card 1389 (02 May 1972) Review of recent activity since 1967

Recent activity is a continuation of renewed activity which started August 1967 and lasted intermittently up to present. Renewed activity in 1967 was initiated by continuous emission of smoke from "1963-vent." At lower end of ~4-km-long "1963-Lava stream" in upper branch of river Glidik (S slope) solfataras emitting a bluish-white smoke were visible. Towards end of August glares were observed and hissing sounds were heard. In beginning of September lava was extruded and formed lava stream in direction of river Sarat (S slope) accompanied by continuous tremors (recorded by mechanical seismographs at Tawonsongo Observatory 1-15 September, and at Argosuko Observatory 2-4 September). This lava sttream attained length of ~1,700 m (September 1967). In following period (during 1968, 1969, 1970, 1971, and the first quarter of 1972) activity still continued [with extrusion of "Lava 1967" as described below].

Formation of lava dome that continuously became higher. Growth of this dome is directed W and S. Formation of lava stream in upper branch of river Iglidik and river Sarat. Accompanying avalanches entering rivers Glidik, Sat, Bang, and Sarat (all of them on the S slope) reaching maximum distance ~1.5 km. Number of avalanches reached its peak in months of March 1968, January 1969, and April 1970 Viz. over 40 times within one month. Bigger avalanches caused burning of forest on upper slopes. Also nuee ardente avalanches very often took place on S. slope reaching maximum distance ~4.5 km in river Glidik. Peak number was recorded during months of April and May 1968, viz. over 500 times within one month. Extrusion of lava was accompanied by minor explosions and volcanic tremors.

Ash eruptions producing greyish black ash columns attained maximum height of ~2.5 miles, occasionally causing light ash showers in three volcano observatories around Mt. Semeru: Argosuko Observatory (S slope, 0.5 km from the summit), Gunung Sawur Observatory (E slope, 11.5 from the summit), and Tawonsongo Observatory (NE slope, 0.5 km from the summit). In night flying incandescent pyroclastics often could be observed [from Tawonsongo], also emission of fire and glares on summit. Strong rumblings could be heard very often, also hissing sounds accompanying eruptions or emission of ash clouds.

Recent activity of Mt. Semeru is considered not dangerous yet. At end of first quarter of 1972 activity is slightly decreasing. To face any possibility of acceleration of volcanic activity in near future, in 1970 "Danger Zone Map" of Mt. Semeru was submitted to local authorities to be used as guidance for eventual evacuation of inhabitants when the situation becomes critical.

Information Contacts: Djajadi Hadikusumo, Geological Survey of Indonesia.

11/1976 (NSEB 01:14) Ejection of ash and nuées ardentes; lava dome growth

The eruption that began on 31 August 1967 continued with ejection of ash and nuées ardentes, and growth of the lava dome.

Information Contacts: D. Hadikusumo, Volcanology Division, GSI; D. Shackelford, Villa Park, CA.
Download or Cite this Report

03/1977 (NSEB 02:03) Long-running eruption continues typical activity

Semeru continued its activity essentially unchanged during February, with lava avalanches, occasional nuées ardentes, and emission of ash and gases.

Information Contacts: J. Matahelumual, Volcanology Division, GSI.
Download or Cite this Report

01/1980 (SEAN 05:01) Dome growth and ash explosions decline

Extrusion of a summit dome began in 1967 and was continuing in late 1979. Until 1974, dome growth was concentrated in the S portion of the summit, shifting since then to the SE but remaining in the summit area. Lava avalanches, nuées ardentes (traveling a maximum of about 7 km), and ash explosions have accompanied the dome extrusion.

During 1979, the rate of dome growth slowed, and ash explosions became weaker and less frequent, occurring at intervals of 45 minutes to 1 hour in contrast to 30-35 minutes in 1977-8. Although almost all of the 1977-8 explosions were recorded by a seismograph 7 km S of the summit, few of the most recent explosions can be detected by this instrument.

Information Contacts: A. Sudradjat and L. Pardyanto, VSI.
Download or Cite this Report

09/1980 (SEAN 05:09) Ash eruptions

Ash eruptions were continuing in late September. However, no additional dome growth has been observed, and nuées ardentes have not been reported since January.

Information Contacts: A. Sudradjat, VSI; D. Shackelford, Fullerton, CA.
Download or Cite this Report

02/1981 (SEAN 06:02) Ash emission and hot avalanches

Ash emission continued at an average rate of once every 56 minutes in November and December. Ash columns typically rose 500-700 m above the crater rim. Some clouds were less ash-rich, as indicated by a grayish color. Incandescent lava fragments were sometimes visible at night. Strombolian-type eruptions have accompanied the formation of the lava dome since extrusion began in 1967.

Lava avalanches from the dome have usually been contained at about 3 km altitude on the S flank of the volcano, in the upper reaches of the Kembar River, but one traveled farther down the river valley in early December. Before this year's monsoon rains VSI has alerted local authorities to the S and SE of the danger of lahars along the Kembar, Kobokan, Rejali, Sat, and Glidil Rivers.

Information Contacts: A. Sudradjat and L. Pardyanto, VSI.
Download or Cite this Report

03/1981 (SEAN 06:03) Nuées ardentes and lava avalanches; one killed, 272 evacuated

Activity increased 28 March. The first nuée ardente moved about 4 km from the summit down the Kembar and Kobokan Rivers (on the S flank) at 1755. During the following days, increasingly intense nuées ardentes reached a distance of more than 7 km from the summit. Four nuées ardentes and 19 lava avalanches (presumably accompanied by nuées ardentes of eruptive origin) were reported on 29 March and four more nuées ardentes and 36 lava avalanches were observed the next day. As of 31 March, tremors were being continuously recorded by the VSI seismograph about 10 km from the summit.

One person was killed by a nuée ardente and 272 others were evacuated. The ongoing rainy season may cause lahars and associated flooding.

Information Contacts: A. Sudradjat and L. Pardyanto, VSI.
Download or Cite this Report

05/1981 (SEAN 06:05) Mudflow kills more than 250

Thirty centimeters of rain in two hours on 14 May dislodged pyroclastic deposits from the upper flanks. Approximately 5-6 x 106 m3 of breccia, volcanic sands, ash, surficial cover, and vegetation flowed down the 40 -60 E flank into the valleys of the Tunggeng and Sat Rivers. The mudflow killed 252 persons, left 152 injured and 120 missing, and flooded 626 hectares of rice fields and 16 villages along the river's banks. It eroded old mudflow deposits and washed away a dike built in 1912 after a similar event had destroyed the city of Lumajang (40 km E of the volcano) in 1901. The devastated area appears to be within the alert zone on VSI's 1973 hazard map.

Fresh nuée ardente deposits on the upper S flank, combined with the onset of the monsoon season, had prompted the VSI to warn local authorities in January of the danger of mudflows S and SE of Semeru. Although a mudflow also moved down the S flank on 14 May, no casualties were reported there. Activity at Semeru was normal during May, with about 80 gas eruptions each day. The lava dome continued to grow at about 100 m3/day.

Information Contacts: A. Sudradjat and L. Pardyanto, VSI.
Download or Cite this Report

08/1985 (SEAN 10:08) Two-year eruption continues

"Semeru has been continuously active during at least the past two years. Activity consists of a blocky lava flow from the Semeru vent accompanied by Vulcanian explosions that occurred 6-10 times/hour during August, sending tephra-rich plumes to 1 km above the vent."

On 4 August, Space Shuttle astronauts [Mission STS51-F] observed a plume extending 100 km W of the summit.

Information Contacts: J. Matahelumual and T. Casadevall, VSI; C. Wood, NASA, Houston.
Download or Cite this Report

12/1985 (SEAN 10:12) Frequent explosions and lava extrusion throughout 1985

"Semeru has been active throughout 1985. The principal activity consisted of frequent small Vulcanian explosions and slow lava extrusion from the summit vent, small rockfalls from the steep-sided walls of the summit lava plug, and occasional nuées ardentes d'avalanche from the lava flow, where it rests on the steep SE flank of the summit cone. These small pyroclastic flows generally remain within 5 km of the summit vent. Typical maximum cloud height for the small Vulcanian explosions is 1,000 m or less. The frequency of explosions decreased steadily from 3,832 in May (125/day) to 1,797 in December (60/day). The monthly average number of rockfalls was about 320. The maximum number of nuées ardentes d'avalanche was 18 in July, declining from 15 in August to five in December (table 1). The composition of a breadcrust bomb sample collected on 17 August is shown in table 2."

Table 1. Monthly numbers of explosions, rockfalls, and nuées ardentes d'avalanche at Semeru, April-December 1985. Explosion and rockfall counts are from seismic records; nuées ardentes are counted from extended rockfall signals on seismic records and from observations from Gunungsawur Observatory at 650 m altitude, 12 km SE of the summit.

    1985   Explosions   Rockfalls   Nuees Ardentes

    Apr      2529          179            0
    May      3832          323            0
    Jun      3748          437            5
    Jul      3321          364           18
    Aug      3192          341           15
    Sep      2357          303           12
    Oct      2315          475           10
    Nov      1464          224            6
    Dec      1797          320            5

Table 2. Whole rock analyses of breadcrust bomb sample collected from Semeru, 17 August 1985. X-ray fluorescence analyses by the USGS Laboratory, Denver, Colorado. Total iron expressed as Fe2O3; loss on ignition at 900°C.

    Component    Value (%)

    SiO2         56.8
    Al2O3        19.9
    Fe2O3         7.61
    MgO           2.28
    CaO           8.09
    Na2O          3.45
    K2O           1.22
    TiO2          0.70
    P2O5          0.18
    MnO           0.18
    LOI           0.01

Further Reference. Suryo, I., 1986, Semeru: Bulletin of the Volcanological Survey of Indonesia, no. 111, 52 p.

Information Contacts: Suparto S. and T. Casadevall, VSI.
Download or Cite this Report

04/1986 (SEAN 11:04) Normal small Vulcanian explosions continue

"Semeru continued to have several small Vulcanian explosions/hour during April. The maximum height of the eruption clouds was ~1 km above the summit. This represents the normal state of activity at Semeru."

Information Contacts: Olas, Suratman, Suparto, Kaswanda, and A. Sudradjat, VSI.
Download or Cite this Report

05/1986 (SEAN 11:05) Explosions continue, nuée adente observed

When . . . visited 7-8 June, small explosions were continuing at intervals of ~5-20 minutes, producing eruption columns that rose <1 km. The fairly ash-rich plumes were generally carried WSW. For a few minutes after each explosion, fine ash fallout was observed around the summit area. During 3 hours of clear weather on 8 June, one [glowing avalanche] was observed, ~55 minutes after the preceding explosion.

Information Contacts: A. Sudradjat, L. Pardyanto, and T. Casadevall, VSI.
Download or Cite this Report

06/1986 (SEAN 11:06) Continued small explosions

Small explosions continued from the summit crater in June, the same style of activity . . . since 1967.

Information Contacts: L. Pardyanto, Olas, Kaswanda, A. Sudradjat, and T. Casadevall, VSI.
Download or Cite this Report

09/1986 (SEAN 11:09) Frequent summit Vulcanian explosions continue

"Semeru continues in its normal state, with frequent Vulcanian explosions from the summit crater."

Information Contacts: L. Pardyanto, Olas, Kaswanda, Suratman, A. Sudradjat, and T. Casadevall, VSI.
Download or Cite this Report

11/1986 (SEAN 11:10) Vulcanian explosions continue

Frequent Vulcanian explosions continued through October from the summit crater.

Information Contacts: Suratman and T. Casadevall, VSI,
Download or Cite this Report

12/1986 (SEAN 11:12) Frequent summit explosions continue

Frequent explosions continued through early January from the summit crater.

Information Contacts: VSI.
Download or Cite this Report

02/1987 (SEAN 12:02) Minor explosions continue

Minor explosions continued through February.

Information Contacts: VSI.
Download or Cite this Report

03/1987 (SEAN 12:03) Normal Vulcanian explosions continue

Normal activity continued . . . with several small Vulcanian explosions/hour during March. Maximum eruption cloud height was ~1 km above the summit.

Information Contacts: VSI; T. Casadevall, USGS & VSI.
Download or Cite this Report

04/1987 (SEAN 12:04) Continued small Vulcanian explosions

. . . frequent, small Vulcanian eruptions.

Information Contacts: T. Casadevall, USGS & VSI.
Download or Cite this Report

06/1987 (SEAN 12:06) Normal Vulcanian activity

. . . Vulcanian activity during May and June.

Information Contacts: VSI.
Download or Cite this Report

07/1987 (SEAN 12:07) Glowing rockfall avalanches enter new drainages

. . . Vulcanian activity during July. Beginning 15 July, glowing rockfall avalanches from the crater entered the Tretes drainage, which lies between the Kobokan drainage SE of the crater and the Kembar, S of the crater. Apparently the upper Kobokan and Kembar drainages have both been filled with material, so avalanches have begun to overflow from them into the Tretes drainage. This change in the flow pattern does not represent a significant change in eruptive activity, but only a change in the direction in which rockfall avalanches are channeled out of the summit crater.

Information Contacts: VSI.
Download or Cite this Report

08/1987 (SEAN 12:08) Vulcanian activity continues; nuées ardentes de avalanche

. . . Vulcanian activity continued through August. Field geologists observed several [glowing avalanches] that traveled down the SE flank . . . .

Information Contacts: VSI.
Download or Cite this Report

09/1987 (SEAN 12:09) Vulcanian activity continues

. . . Vulcanian activity continued during September.

Information Contacts: VSI.
Download or Cite this Report

10/1987 (SEAN 12:10) Vulcanian activity continues

. . . Vulcanian activity in October.

Information Contacts: VSI.
Download or Cite this Report

12/1987 (SEAN 12:12) Continued Vulcanian activity

Vulcanian activity continued during November and December.

Information Contacts: VSI.
Download or Cite this Report

02/1988 (SEAN 13:02) Continued Vulcanian activity

. . . Vulcanian activity during February.

Information Contacts: VSI.
Download or Cite this Report

03/1988 (SEAN 13:03) Vulcanian activity continues; clouds to 7.5 km

. . . Vulcanian activity in March. A NOTAM on the 26th reported that clouds reached 7.5 km altitude and were moving E.

Information Contacts: VSI; N. Krull, FAA.
Download or Cite this Report

04/1988 (SEAN 13:04) Vulcanian explosions continue in 21-year eruption

. . . Vulcanian activity during April.

Information Contacts: VSI.
Download or Cite this Report

06/1988 (SEAN 13:06) Vulcanian activity continues

Normal Vulcanian activity continued during May and June.

Information Contacts: VSI.
Download or Cite this Report

07/1988 (SEAN 13:07) Vulcanian activity persists

. . . normal activity in July. Explosions every few minutes ejected plumes as high as 1 km.

Information Contacts: VSI.
Download or Cite this Report

05/1989 (SEAN 14:05) Frequent lava avalanches and nuees ardentes

Activity continued in March 1989, with lava flows, avalanches of lava debris, and [pyroclastic flows] that sometimes generated lightning. The number of lava avalanches increased from the previous month, with debris extending 700-1,000 m from the summit. Some associated [pyroclastic flows] reached 1,000-2,000 m from the summit. Thunderous incandescent lava explosions sometimes produced plumes that rose 400-700 m above the summit. During March, seismic stations near Semeru recorded 3,263 explosion earthquakes, 83 avalanche events, 33 strong and five local tectonic shocks, five [pyroclastic flow] signals, and two A-type volcanic events.

Information Contacts: VSI.
Download or Cite this Report

07/1989 (SEAN 14:07) Vulcanian explosions, lava avalanches, and nuées ardentes

The small Vulcanian explosions and avalanches . . . continued in late July. During the second week of the month, thick ashfalls occurred at Sawur (13 km SW of the summit), Tawangsongo, and Argosuko observatories. Ash and incandescent tephra rose 50-100 m above the crater through late July. Avalanches of lava debris reached 750 m from the crater, while associated [pyroclastic flows] traveled 1,000-4,000 m. No changes on the lava dome were observed. The type and number of earthquakes recorded 1-20 July were: explosion (793), collapse (1), volcanic A-type (9), volcanic B-type (8), and [pyroclastic flows] (11). Although activity has increased, it is still considered within the normal range.

Information Contacts: VSI.
Download or Cite this Report

07/1990 (BGVN 15:07) End to Vulcanian activity and dome growth; new collapse pit in crater

The press reported that heavy ashfall occurred 21-22 March, with accumulations of up to 5 mm in Malang (20 km NW). VSI noted that the activity was considered "normal" . . . .

By the beginning of July, however, local inhabitants reported that this activity had stopped. A visit to the crater on 28 July revealed a large collapse within the crater formerly occupied by the lava dome (figure 1). The new pit was roughly 200 m deep. Material observed sloughing down the walls caused little dust clouds. No sign of activity was visible within the new pit; one group of fumaroles and light sulfur deposition was found on the SW inner wall of the crater, 30 m below the rim.

Figure 1. Sketch map of the active crater at Semeru, 28 July 1990. Courtesy of Jacques Durieux.

Information Contacts: J. Durieux, GEVA, France; Jakarta Post.
Download or Cite this Report

03/1991 (BGVN 16:03) Ash emissions; 400-m-long lava flow

Eruptive activity and the number of explosion earthquakes sharply decreased from the beginning of May to December 1990. However, ash was frequently emitted to 300-400 m above the crater, and one large explosion on 21 December ejected ash to 1,000 m. Avalanches to the E (into the Besuk Kembar river) were also common. In February, observers at Gunungsawur Observatory (~10 km SE of the crater) reported a lava flow that traveled 400 m from the crater. An average of 140 explosion earthquakes and one tectonic earthquake were recorded daily in March, but no tremor episodes were detected.

August 1990 aerial photographs showed that the active crater (Jonggring Seloko) was a pit ~150 m deep and 850 m in diameter.

Information Contacts: W. Modjo, VSI; AP.
Download or Cite this Report

04/1991 (BGVN 16:04) Continued explosions and seismicity

Explosions continued during April, with column heights averaging 300-400 m, and explosion earthquakes recorded an average of 112 times/day . . . . Seismographs also recorded 2-3 daily avalanches of material off the lava flow erupted 17 February. A total of one deep volcanic earthquake and 18 tectonic events were recorded.

Information Contacts: W. Modjo, VSI.
Download or Cite this Report

11/1991 (BGVN 16:11) More frequent explosions and tremor; lava avalanches

Emission of gas plumes, sometimes containing ash, to a maximum height of 600 m continued through early December. The press, citing an unnamed local volcanologist, reported that small explosions occurred as often as every 5 minutes after 4 December. Avalanches extended 500 m downslope from the growing lava dome. Explosion shocks were recorded at rates of 35-110/day, accompanied by 2-10 avalanche events daily. Volcanic tremor was more frequent in November than in October. Although activity was increasing, it remained within the normal range for the eruption . . . .

Information Contacts: VSI; UPI.
Download or Cite this Report

10/1992 (BGVN 17:10) Frequent explosions eject 1-km clouds; summit morphology described

During an 18-hour visit to the summit region 21-22 October by the German-Indonesian Volcano Expedition, volcanic activity was confined to the Jonggring Seloko crater (figures 2 and 3). At least 35 explosions occurred during the summit visit, most associated with steam releases from the crater bottom, sometimes forming mushroom-shaped clouds that rose ~1 km above the crater. The average time between explosions was ~22 minutes, but varied between 3 and 46 minutes.

Figure 2. Sketch of the summit region of Semeru. The northern part of this sketch is taken from the 1941 map in Reksowirogo (1979). Relative altitude measurements taken in 1992 at the locations shown agree well with the 1941 map. The southern area is sketched from the 1992 observations. Elevations given were measured relative to the summit. All other contour lines and distances are estimates. Contour interval (heavy lines) is 25 m; intermediate contours at 12.5 m intervals are included on part of the map. Although individual values may not be exact, the sketch accurately reconstructs the summit morphology. Courtesy of Margaret Hellweg.
Figure 3. Photograph of the Jonggring Seloko crater of Semeru, 21 October 1992, taken from the N crater rim. Alternating layers of lava and ash can be seen in the crater walls; steam is rising from the lava dome. The crater, open to the SE, is ~300 m in diameter and 150 m deep. The S coast of Java is visible at left center. [Photograph taken by Horst Rademacher; originally in 19:1.]

One phase of activity that could not be correlated with the release of steam from any particular fumarole was a rhythmic, puffing sound emitted from the bottom of the crater. The sound was reminiscent of a steam locomotive starting to pull a heavy freight train. The frequency of the "puffs" ranged from 1.5 to 0.6 Hz. Sometimes the sound sequence lasted only a short time, with as few as six separate puffs. At other times it continued for more than 3 minutes with >100 puffs. The frequency and duration of the puffs remained relatively constant during each series, no matter how long it lasted. The rhythmic sound was also heard on 23 October at Oro-oro Ombo, ~7 km N of the summit.

The features in the N region of the summit conformed well to the 1941 map in Reksowirogo (1979). However, the S part of the summit region has changed extensively. Where the 1941 map shows the N edge of the crater, there is now an E-W valley filled with ash, lapilli, tuff, and some volcanic bombs. This valley is ~50 m deep, and ends to the E in a ridge, shown as part of the crater wall on the 1941 map. The valley separates the summit (Mahameru) from the new rim of the Jonggring Seloko crater. The crater is nearly cylindrical with a diameter of roughly 300 m and an estimated depth of 150 m. The very steep crater walls exhibit fumarolic and solfataric activity. Steam explosions occurred occasionally and the rim was heaped with ash. The crater walls show alternating layers of andesitic or rhyolitic lava and ash. The N, W, and SW walls of the crater are relatively intact. The highest point of the rim in the N was measured to be 40 m lower than the Mahameru summit. The crater opens to the SSE, allowing volcanic material to flow out, and there is a shallower gap in the NE wall. Except for the gas vents in the walls, nearly all of the volcanic activity was concentrated at the bottom of the pit where a double ash ring surrounded a small lava dome or plug ~30 m in diameter. Near the SSE opening of the crater is an area of additional activity. From this inaccessible location, a small, old, aa flow seems to have been extruded.

The team also made broadband and short-period measurements of seismic activity and volcanic tremor. . . .

Reference: Reksowirogo, L.D., 1979, Semeru, in Kusumadinata, K., ed., Data Dasar Gunungapi Indonesia: Volcanological Survey of Indonesia, 820 p. (p. 304-319).

Information Contacts: K. Brotopuspito, GMU; M. Hellweg, USGS; H. Rademacher, Orinda CA, USA.
Download or Cite this Report

01/1994 (BGVN 19:01) Lava avalanches and pyroclastic flows kill six people

On 3 February, VSI observers and local residents near Semeru heard a sharp thunder-clap at 0350 and later saw falling ash. Lava avalanches and pyroclastic flows from the summit crater descended SE along the Kembar and Kobokan rivers, reaching 7.5 km and 11.5 km from the summit, respectively. Volcanic materials also entered Sumbersari village (8 km SE of the summit), located between the rivers. Four people were killed; another three were injured, and two of those later died. Following the lava avalanches and pyroclastic flows, 275 people were evacuated from Sumbersari, where many houses and 1.5 km2 of plantation land were destroyed. A seismic station maintained by VSI was also destroyed.

Visual and seismic activity had increased in late 1993, with frequent collapses from the summit lava flow SE into the area between the Kembar and Kobokan rivers. Volcanic earthquakes had been recorded since October, and peaked on 25 December 1993. Continuous tremor with a maximum amplitude of 26 mm was recorded from 26 January until 3 February 1994 (figure 4).

Figure 4. Diagram showing seismicity at Semeru, 7 January–14 February 1994, with A- and B-type events along with tremor (top), and avalanche and explosion events (bottom). Courtesy of VSI.

Eruptive and seismic activity continued after 3 February, but the intensity and energy had decreased. The daily number of explosion earthquakes increased to 360 on 5 February, then declined again, but remained >70/day through mid-month (figure 4). Volcanic tremor was recorded again on 9-14 February with a maximum amplitude of 13 mm. Ash eruptions generated clouds reaching heights of up to 700 m above the summit. Pyroclastic flows and lava avalanches traveled as far as 3 km down the Kembar and Kobokan rivers. Lava extruded from the crater over the S rim formed a 750-m-long lobe moving down the S flank toward the Kembar river.

Information Contacts: W. Tjetjep, VSI; A. Brodsholl, GMU.
Download or Cite this Report

07/1994 (BGVN 19:07) Small ash eruptions to 500 m above the summit

Eruptive activity on 3 February 1994 produced ashfalls, lava avalanches, and pyroclastic flows, destroying a village and killing 6 people (19:01). Total volume of the pyroclastic-flow deposits was about 6 million m3.

During 5-14 August observations, visual and seismic activity . . . were normal. The daily number of explosion earthquakes fluctuated between 40 and 100 events, and volcanic tremor was occasionally recorded with a maximum amplitude of 4 mm. Ash eruptions generated clouds up to 500 m above the summit. There were no pyroclastic flows or lava avalanches.

Information Contacts: VSI.
Download or Cite this Report

10/1994 (BGVN 19:10) Normal mild explosive activity in August; slow lava extrusion

Several hours of observations were made on 7 August by J. Sesiano from the N rim of Jonggring Seloko crater. Gas-and-ash plumes rose hundreds of meters above the crater. Generally mild explosions occurred at intervals of ~15-20 minutes, each resulting in a white plume that barely rose above the crater rim. The explosions originated from the same vent where very slow lava extrusion was feeding a flow moving SE that exhibited red glow and incandescent cracks at night. Based on the movement of unique morphological features of the lava flow, a velocity of tens of meters/day was estimated. Incandescent boulders were thrown from the flow front by violent explosions that occurred an average of 4-5 times/day. Collapses of the lava flow, located on a 35° slope, sent boulders down into the valley accompanied by small pyroclastic flows. Whistles and roaring noises were heard almost continuously, similar to the noises heard at a busy airport: jets taking off, landing, turning off engines, and disappearing into the distance. Thunder-like claps, rhythmic pulses (~1 Hz frequency, for ~10 minutes), and other sounds could also be heard. Seismicity recorded by VSI during 5-14 August indicated that activity was at normal levels, with 40-100 explosion events/day (19:07).

A NOTAM issued from the Bali Flight Information Region (FIR) on 24 October noted volcanic ash from Semeru, but the cloud top and drift direction were unknown.

Information Contacts: J. Sesiano, Univ de Genéve; BOM Darwin, Australia.
Download or Cite this Report

03/1995 (BGVN 20:03) Ash eruptions, lava avalanches, and summit glow

Activity from the Jonggring Seloko summit crater continued in January and February 1995. Ash eruptions rose as high as 600 m above the summit. Lava avalanches increased in frequency during January and early February, and traveled down the Kembar River drainage to a distance of 750 m from the summit. Glow was sometimes observed 50-100 m above the summit. On the morning of 6 February three pyroclastic avalanches moved 800-1,000 m from the summit along the Kembar River before turning into the Kobokan River.

Tremor and volcanic earthquakes (both A- and B-type) were variable, with 20-110 events/day and 1-12 events/day, respectively (figure 5, top). Maximum tremor amplitude was 3-18 mm during the first week of January before increasing and peaking at 30 mm on the 8th. The daily number of explosions, recorded by a seismograph, showed an overall decline from 40-190 events/day in December to <100 events/day in mid-Mar (figure 5, bottom).

Figure 5. Tremor events and B-type volcanic earthquakes (top), and explosion and avalanche events detected by seismograph (bottom) at Semeru, December 1994-March 1995. Courtesy of VSI

Information Contacts: W. Tjetjep, VSI.
Download or Cite this Report

07/1995 (BGVN 20:07) Hazard status raised; mid-July explosion earthquakes, pyroclastic flows

Increasing seismicity, avalanches, and pyroclastic flows with runout distances over 3 km began in early June 1995 (figure 6). The local government (Lumajang Regency) issued a warning on 21 June, but on 17 July they raised the hazard status and issued a volcano alert.

Figure 6. Summary of Semeru activity during April-July 1995. Courtesy of VSI.

On 19 July, explosion earthquakes having maximum amplitudes of 35 mm were recorded. On 20 July at 1140, seismographs recorded continuous earthquakes associated with avalanche-type pyroclastic flows. At 1350 on 20 July, the Semeru Volcano Observatory informed local authorities, the Mt. Semeru Project, and the Ministry of Public Works that lava avalanches and pyroclastic flows were descending SE from Semeru's summit along the Kobokan river (figure 7). A warning was sent to local residents near the Kobokan river in the villages of Sumbersari, Renteng, Deli, and Sukosari. The 20 July pyroclastic flows advanced 9.5 km from the summit along the Sumbersari and Lengkong rivers (figure 7). The pyroclastic flows ceased at 1550 on 20 July; no one was reported injured during this most recent episode, although in a previous episode, in February 1994, lava avalanches and pyroclastic flows killed six people in Sumbersari.

Figure 7. Map of Semeru's SE quadrant and 20 July 1995 pyroclastic-flow deposits. Courtesy of VSI.

On 21 July 1995, three pyroclastic avalanches descended along the Kembar river travelling a distance of 2 km. After 22 July, seismic, avalanche, and pyroclastic flow activity decreased somewhat. Still, on 27 and 28 July, pyroclastic avalanches descended the Kembar and Kobokan rivers, reaching lengths of 1 and 2 km, respectively.

A Semeru eruption was mentioned in an aviation alert on 3 August. The alert, which was based on a report from Qantas Airlines, stated that the estimated eruption time was 1500; the column reached ~4,600 m (roughly 900 m above the summit) and was blown W at 22 km/hour. Convective cloud cover prevented the Synoptic Analysis Branch from searching for the plume.

Information Contacts: W. Tjetjep, VSI.
Download or Cite this Report

10/1995 (BGVN 20:10) Explosions and pyroclastic flows continue

The VSI reported that by 3 August a tongue of glowing lava had reached 300 m long; at 1932 that evening the lava collapsed to feed lava avalanches. Qantas airlines reported additional activity at 1510 on 8 August, describing volcanic "smoke" near Semeru to above 4 km. Two days later, around 1530 on 10 August, a Qantas flight reported an ash cloud to 9 km altitude with a SW drift.

VSI noted that during Aug-Oct small-to-moderate explosions and avalanches continued from the Jonggring Seloko summit crater. Plumes rose to a maximum of 600 m above the summit; the average plume height was 300-500 m. In August and September, pyroclastic flows often traveled down the Kember River, then descended the Kobokan River, reaching a distance of 1-3 km. The frequency of lava avalanches increased in September, extending along the Kember River for up to 500 m from the summit.

Earthquakes associated with the pyroclastic flows were variable, with 1-16 events/day through early October; after that the frequency of earthquakes decreased. Increasing numbers of volcanic earthquakes (both A-and B-type) started on 11 October and continued until the end of the month, fluctuating at 1-14 events/day (figure 8). The number of explosion earthquakes was typically 45-109/day (figure 06sem08f), except on 26 and 27 September, when there were only 33 and 24 events, respectively.

Figure 8. Eruptive activity at Semeru as detected by seismograph, August-October 1995: pyroclastic flows and volcanic earthquakes (top), explosions and avalanche events (bottom). Courtesy of VSI.

Information Contacts: W. Tjetjep, VSI; BOM Darwin, Australia.
Download or Cite this Report

01/1996 (BGVN 21:01) Explosions, pyroclastic flows, and lava avalanches continue

Volcanic activity continued until the end of 1995 at a level of intensity comparable to August-October (BGVN 20:09). During November and December, small to moderate explosions and avalanches occurred from the Jonggring Seloko summit crater. The average plume height was 300-500 m. Pyroclastic avalanches descended along the Kembar river to a distance of 500-1,000 m from the summit. The number of lava avalanches increased during November, traveling down the Kembar river up to 300 m from the summit. On 27 December an incandescent lava flow traveled 500 m; during this event volcanic tremor was recorded with a maximum amplitude of 3 mm.

The frequency of volcanic earthquakes (both A- and B- types) during the November- December period ranged from 1 to 10 events/day. Volcanic tremor was recorded on 1, 2, 17, and 18 November; tremor from 15 to 18 December increased to 3-8 events/day (figure 9). Explosion earthquakes were variable (31-136 events/day), with two minima on 5 and 25 December (24 and 19 events/day, respectively) (figure 9).

Figure 9. Eruptive activity at Semeru as detected by seismograph, November - December 1995: Daily number of tremor and volcanic earthquakes (top), explosions and avalanches (bottom). Courtesy of VSI.

Typical activity for this volcano was observed by Steve O'Meara on 13 November from the rim of Tengger Caldera. Thick cauliflower-shaped columns of gray ash rose up to 200 m high every 15-20 minutes, and the sky to the SW was spotted with ash clouds from previous eruptions. One event lasted ~5 minutes, generating a dark gray ash cloud that caused ashfall on the S slopes before detaching from the summit. Another eruption cloud spilled over the SW rim and flowed downslope.

Information Contacts: Wimpy S. Tjetjep (Director), Volcanological Survey of Indonesia (VSI), Jalan Diponegoro 57, Bandung, Indonesia; Steve O'Meara, PO Box 218, Volcano, HI 96785, USA.
Download or Cite this Report

06/1996 (BGVN 21:06) Eruptions form ash plumes

A pilot report from Qantas Airlines on 5 May noted activity around 1800 generating a plume to ~10.5 km altitude. Eruptive activity was again observed from the same flight at 1745 on 7 May, but the ash cloud was only ~1 km above the summit and drifting NE.

Based on a report from Japan Air Lines, another aviation notice of volcanic ash from Semeru was posted at 0335 on 11 May. The report indicated that ash extended ~300 m above the peak and was moving SE at 18.5 km/hour. Lauda Air reported a low-level ash cloud around 1,300 m altitude on the early morning of 12 May, and a Qantas Airlines flight observed periodic emissions later that evening that did not rise above 6 km altitude. Satellite imagery throughout 5-12 May showed no ash plumes.

Information Contacts: Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin, NT 0801, Australia; Jim Lynch, NOAA/NESDIS Synoptic Analysis Branch (SAB), Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA.
Download or Cite this Report

09/1996 (BGVN 21:09) Intermittent pilot reports of eruptions from August to October

A pilot report from Qantas Airlines on 1 August noted an ash cloud at an altitude of 4,000 m. Animated visible and infrared GMS satellite data through 0832 on 2 August did not reveal any discernible ash plume.

Another Qantas pilot report indicated that Semeru erupted at 1625 and 1637 on 12 September with ash reaching 4,600-m altitude and drifting NW; no plume was seen on satellite imagery. At approximately 0640 the next day a localized plume was evident on satellite imagery drifting SSW to ~35 km away. Eruptive activity was again observed by Qantas pilots who reported at 1154 on 29 September thick black "smoke" at 6 km altitude. Another aircraft report at 2110 later that day indicated ash to 6 km moving N and NW. Satellite data showed local high cloud cover throughout the day, but no apparent ash plume.

On 6 October an eruption was reported by Qantas pilots at 1418. The dense plume was rising to ~4.6 km altitude with no significant drift.

Semeru is the highest and one of the most active volcanoes of Java. It lies at the S end of a volcanic massif extending N to the Tengger Caldera and has been in almost continuous eruption since 1967.

Information Contacts: Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin, NT 0801, Australia; NOAA/NESDIS Satellite Analysis Branch (SAB), Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA; Tom Fox, International Civil Aviation Organization (ICAO), 999 University Street, Montreal, Quebec H3C 5H7, Canada (Email: tfox@icao.org).
Download or Cite this Report

11/1996 (BGVN 21:11) A 2-km-long pyroclastic flow on 7 October; minor ashfall

Ongoing pyroclastic flows associated with lava avalanches tended to be larger in October than September. On 7 October, one such pyroclastic flow ran down the Besuk Kembar river to a distance of ~2 km. At the end of October ash had accumulated to ~1 mm thick in villages around the volcano. Seismicity was dominated by explosions and avalanche earthquakes.

Semeru, the highest peak on Java, has frequent pyroclastic flows, lahars, and lava flows. Since 1967, many Vulcanian eruptions have accompanied lava dome extrusion.

Information Contacts: Wimpy S. Tjetjep, Volcanological Survey of Indonesia, Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: vsimvo@ibm.net).
Download or Cite this Report

06/1997 (BGVN 22:06) Pilots saw April-June ash at 3- to 7-km altitudes

Aviation ash advisories were issued on 21-23 March, 16-19, and 30 May, and 6 June following reports by Qantas pilots who encountered ash at altitudes of 3.5-7 km. Another Qantas report on 10 July described light ash as high as 10 km altitude. Lower level (3-6.1 km) ash was encountered again by Qantas flights on 10, 13, 20, 23 and 24 July. Neither BOM nor SAB observed ash in satellite imagery because of clouds over the mountains.

A pyroclastic flow and minor ashfall was reported in October 1996, along with explosions and avalanches earthquakes (BGVN 21:11). Semeru is the highest and one of the most active volcanoes of Java. It lies at the S end of a volcanic massif extending N to the Tengger Caldera and has been in almost continuous eruption since 1967.

Information Contacts: Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin NT 0801, Australia; NOAA/NESDIS Satellite Analysis Branch (SAB), Room 401, 5200 Auth Road, Camp Springs, MD 20746, USA.
Download or Cite this Report

08/1997 (BGVN 22:08) Frequent explosions and ash plumes; two climbers killed

Activity observed during fieldwork in July 1997 consisted of frequent short-lived Vulcanian explosions. Continuous crater observations were made over more than 5 hours on the morning of 22 July from the Gunung Sawur observatory, 11 km SSE of the volcano. During that time 18 "cannon-like" explosions were each followed by rapidly declining ash emission at intervals of 2-40 minutes with a mean of 18 minutes. Explosion durations ranged from about 1 to 3.5 minutes; plume heights remained low, from a few hundred meters up to 1.5 km maximum. The plumes were blown by the wind as soon as they rose above the crater rim, except for the strongest explosions. Ash sometimes fell at the observatory. Blocks were occasionally seen rolling within the S-SW breach of the crater and glowing pyroclastic material was seen at night. The explosions could be heard 9 km from the crater but not from the observatory. Some explosions were accompanied by base surges, but they were limited to the interior of the crater.

During a 6-hour stay in the summit area on 26 July, 19 explosions were seen. They were separated by intervals of 2-38 minutes with a mean of 15 minutes (or 17 minutes if the last two intervals of 2 and 4 minutes are discarded), suggesting that activity remained stable since 22 July. Most explosions sent only ash plumes above the highest point of the crater rampart. The plumes immediately drifted SE with a strong wind. About 1/3 of the explosions threw blocks well above the N crater rim and some fell on the pyroclastic cone. A brief visit to the rim of the active crater showed that a pyroclastic rampart was being built between the S-SW breach and the active vents. In contrast to the pre-1994 through 1995 eruptions, the bottom of the crater could not be seen from the NE crater rim. No evidence for dome or lava flow emplacement within the present funnel-shaped crater could be seen from the NE crater rim.

Aviation warnings. Volcanic ash advisories for Semeru have been issued frequently since March (BGVN 22:06) At least two such advisories were issued during August after aviators for Qantas Airlines reported ash plumes. On 10 August a Qantas flight flying from Sydney to Singapore reported a plume between 7.6 and 9.1 km (25-30,000 feet) altitude that was drifting S near its base and N at its top. Another plume was seen on 30 August to 8.5 km (28,000 feet) altitude. No evidence of volcanic plumes was seen on either day in satellite imagery.

Two climbers die near crater. According to press reports, two German mountain climbers died near the crater on 2 September after being struck by large ejected ballistics. The two men were part of a group of 17 from a Munich-based climbing club. The victims, together with the group leader, had separated from the group to check the crater when the accident occurred. Warning signs not to approach the crater were posted along the path.

Information Contacts: Jean-Luc Le Pennec, Laboratoire de Petrologie Magmatique, CEREGE - Universite Aix-Marseille III, BP 80, 13545 Aix-en-Provence 04, France; Alain Gourgaud, Centre de Recherches Volcanologiques, 5 rue Kessler, 63038 Clermont Ferrand, France; Isya N. Dana, Igan Sutawidjaja, and Eddy Mulyadi, Volcanological Survey of Indonesia, Jalan Diponegoro 57, Bandung 40112, Indonesia; Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin NT 0801, Australia; Agence France-Presse, Paris, France.
Download or Cite this Report

10/1997 (BGVN 22:10) Ash plumes during October and November

Satellite imagery revealed an ash cloud at a height of ~8.5 km near Semeru on 16 October. Winds at the level of the ash cloud were from the W to NW at 27-37 km/hour. On 22 October another small ash signature originating from Semeru was observed on satellite imagery. The plume was ~46 km long, ~18.5 km wide, and extended to the WNW. The height of the plume was below 7.3 km. On 9 November a volcanic cloud with a top at 4,200 m was reported; the cloud was drifting SW.

Information Contacts: Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin NT 0801, Australia.
Download or Cite this Report

05/1999 (BGVN 24:05) Mass wasting in March; ash eruptions continue; 9-km-high ash cloud in May

Due to increased seismicity, officials raised the status to "Caution" during the week of 23-29 March. Earlier, during the week of 9-15 March a white-gray ash plume attained heights of 400-500 m and the number of events involving debris flows rose from 6 to 42 (with a maximum run-out of 2 km). In addition, weekly volcanic B-type events increased from 1 to 35, tectonic events went from 9 to 27, and explosions increased from 280 to 385. From 23 to 29 March there were 224 earthquakes related to emissions. In addition there was one volcanic A-type, one volcanic B-type, and 14 events associated with moving debris.

On 19 April the Darwin Volcanic Ash Advisory Center (VAAC) issued an advisory to aviators, citing reported eruption ash clouds at 9 km. There was no evidence of the ash cloud from satellite imagery.

Seismic events decreased during 27 April-3 May, but a white-gray ash plume continued to reach up to 600 m. There was a marked increase in seismic events from 4-17 May. From 18-24 May the ash plume varied from white-gray to white-brown and extended to between 400 and 600 m above the summit. Eruptions dominated the seismic record, with a decrease in volcanic events. During the week pilots reported occasional ash clouds drifting NW. On 24 May the plume height reached ~6 km, drifting NW.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

08/1999 (BGVN 24:08) Ash emissions and pyroclastic flows during June-September

Ash emissions and pyroclastic flows continued at Semeru during June-September. In early June emissions of "white colored ash" rose up to 700 m above the summit. Lava avalanches flowed along the Besuk Kembar river valley to distances of up to 750 m from the crater. A pilot reported seeing the top of an ash plume drifting northeast at 6,100 m altitude at 0944 on 13 June. Explosions and lava avalanches occurred frequently during the first week of July, although thick haze often precluded visual observation. On 16 July a pyroclastic flow along the Besuk Kembar river reached a distance of 2 km from the summit.

During the week of 3-9 August white-brown ash emissions rose 600 m above the summit and explosions and avalanches increased in number. At 0410 on 5 August a pilot reported a volcanic ash plume at 6,100 m altitude moving west. During 10-16 August there were eight ash explosions producing columns reaching 500 m above the summit. Five lava avalanches flowed down the Besuk Kembar river valley. Pyroclastic flows and rockfalls moving 2 km down Besuk Kembar river originated from Jonggring Seloko Crater during 18-23 August. Scientists at Sawur Observatory could see lava rockfalls running 400-700 m down Besuk Kembar.

J. Bardintzeff reported that on 15-16 August activity seemed to alternate from rest to explosiveness over periods of several hours. Explosions followed each other at intervals of 15 minutes, but later this interval increased to 1 hour. The first explosion of the period was the strongest and generated a plume 1,000 m high. Explosions were observed at 0732, 0812, 0840, 0905, and 0950 on 16 August.

Pyroclastic flows and rockfalls, with moderate ash emissions, continued in September. An ash explosion during the week 14-20 September produced thick dull-white to dark-colored ash that reached 500 m above the summit.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Jacques-Marie Bardintzeff, Laboratoire de Petrographie-Volcanologie, bat 504, Universite Paris-Sud, 91405, Orsay, France (Email: bardizef@geol.u-psud.fr).
Download or Cite this Report

09/1999 (BGVN 24:09) Short-lived Vulcanian explosions continuing from Jonggring Seloko Crat

The activity at Jonggring Seloko Crater in mid-September 1999 was very similar to that observed in the last recent years at the volcano. It consisted of short-lived non-sustained Vulcanian explosions producing 300-1,000-m-high ash plumes.

On 17 September there were 17 explosions witnessed during day-time hours. The time interval between two successive explosions ranged from 1 to 71 minutes, with an average of one explosion every 36 minutes. The next day 25 explosions were witnessed with 1 to 75 minutes between explosions and an average of one explosion every 32 minutes. These consistent statistics suggest that the present level of activity is lower than that observed in July 1996 and 1997 (BGVN 22:08). Of the 18 explosions closely witnessed, only two were capable of sending ballistic blocks higher than the N crater rim. All ballistic material felt back into the crater. However, the presence of fresh impact structures on the northern pyroclastic rampart of Jonggring Seloko Crater indicated that it is still occasionally showered by pyroclastic blocks.

The morphology of the crater floor changed considerably after the 1994 and 1995 eruptions. In mid-1996 and 1997 the bottom of Jonggring Seloko Crater was too deep to be visible from the NE crater rim. Observations on 18 September 1999 showed that the floor of the crater had risen several tens of meters and about 2/3 of the crater floor could be clearly seen. No evidence of lava or dome extrusion could be observed because of a thick carapace of pyroclastic ejecta and scree. The floor consists of an irregular platform. The southern part of the platform showed evidence of a recent subsidence event (scalloped normal faulting of ~10 m). The platform contained three principal active vents covered by their own ejecta. The central vent was partly surrounded by a small pyroclastic crescent.

Unsteady noisy steam emissions occurred sporadically either from the major vents or from other smaller vents on the crater floor. Larger explosions occurred only from the three principal vents and frequently progressed from the western to the eastern vent during the same explosion event. A moderate explosion at the central vent, observed from the NE crater rim, started with a booming sound followed by the noisy fallback of ballistic material into the crater. Convective uplift of the ash cloud allowed clear observation of the vent area which showed ash geysering silently ~20-40 m above the vent (with "cocktail" projections) for a few tens of seconds. The floor of the crater showed several dark areas, probably corresponding to wet zones, suggesting that water plays an important role in the explosive activity of Jonggring Seloko Crater.

Information Contacts: Jean-Luc le Pennec, Institut de Recherche pour le Developpement and Institut de Physique du Globe de Paris. Tour 26, case 109, 4 place Jussieu, 75 252 Paris cedex 05, France (Email: lepennec@ipgp.jussieu.fr); Sandrine Poteaux, 6 Villa Daviel, 75013 Paris, France (Email: mpoteaux@club-internet.fr); Isya N. Dana, Volcanological Survey of Indonesia, Jalan Diponegoro No 57, Bandung 40122, Indonesia (Email: isya@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

07/2000 (BGVN 25:07) Ongoing eruptive activity; 27 July explosion causes injuries and two fatalities

Semeru has been undergoing nearly constant eruptive activity since 1967. Volcanological Survey of Indonesia (VSI) reports through mid-September 1999 (BGVN 24:09) and earlier described seismicity (including seismically detected pyroclastic flows) and ongoing eruptive outbursts. Accessible Darwin VAAC reports since 3 June 1998 help to characterize the long-term eruptive patterns (table 3). VSI reports are not available for September 1999 through January 2000.

Table 3. A summary of aviation reports (Volcanic Ash Advisories) describing Semeru's plumes during 3 June 1998-21 August 2000. The first two columns describe the time and date when a report was issued. Time entries with commas signify that multiple reports were generated with similar comments. Where available, the time of the observations appear with the comment. Dash marks indicate lack of mention in report. Note that for plume heights, Semeru's summit lies at 3,676 m above sea level. Information sources include air reports (for example, routed via airlines, AIREPS), pilot reports (PIREPS), Notice to Airmen (NOTAM), satellite data, and reports from ground observations. Source data was provided by the Darwin VAAC.

    Time  Date  Information  Comment
    (GMT)       Sources
          Plume height             Satellite confirmed    Clouds
          above sea level (km)         ash (Y/N)          (Y/N)

    1998
    0525  03 Jun  AIREP      Volcanic activity observed S of Surabaya, cloud
                             moving S.
                -                          N                --
    0635  11 Jul  AIREP      Small volcanic plume.
               6.1
    0635  31 Aug  AIREP      Small ash plume.
               6.1
    1500  01 Sep  AIREP      Volcanic activity observed at 1037.
               7.6                         N                -
    0800  02 Sep  AIREP      Volcanic activity observed at 0551.
               5.2                         N                -

    1999
    1228  19 Apr  AIREP      Eruption observed at 1003.
               7.6                         N                -
    1003  13 Jun  AIREP      Plume tops seen.
               6.1                         N                --
    0942  09 Jul  NOTAM      Report of ash cloud.
               6.1                         N                -
    1226  16 Jul  AIREP      Eruption reported at 0905. Weak ash plume
                             apparent on satellite imagery extending 16.7 km
                             WSW at 0936; no ash apparent on subsequent lower
                             resolution imagery at 1030 and 1130.
               4.6                         Y                -
    1817  16 Jul  AIREP      Satellite imagery shows no further evidence of
                             ash cloud at 1732.
                                           N                -
    0451  05 Aug  AIREP      Reported plume at 0350; satellite imagery at 0232
                             showed no evidence of ash cloud.
               6.1                         N                -
    0538  05 Aug  AIREP      Follow-up to plume (reported above).
               6.1                         N                Y
    0304  23 Aug  NOTAM      Volcanic ash drifting SW; satellite image at 0132
                             and last 3 hourly images (no plume visible).
               4.6 (top)                   N                N

    2000
    1144  13 Jun  AIREP      Ash plume.
               7.6                         N                -
    1211  13 Jun  AIREP      Ash plume.
               7.6                         N                -
    1228  23 Jun  AIREP      Ash plume at 0445.
               4.6                         N                -
    1128  16 Jul  AIREP      Ash cloud at 0335.
               7.6                         N                -
    0946  18 Jul  AIREP      Ash cloud 0600.
               9.2                         N                -
    1536, 18 Jul  AIREP      Ash cloud follow-up but cloud appears to have
    2129                     dissipated.
                                           N                -
    0044  19 Jul  NOAA       Satellite imagery at 2115 and 2330; ash extending
                             56 km WSW bearing 257° from Mt. Semeru, plume
                             width not more than 11 km; winds in area suggest
                             height of ash above 5.5 km.
               9.2                         Y                -
    0652, 19 Jul  GMS-5 satellite and Meteorological &
    1245,         Geophysical Agency of Indonesia
    1837                     Apparently undergoing a phase of enhanced
                             activity; ground based reports over last month
                             have given plume heights of 4.6 km; no ash clouds
                             observed by satellite since 0030.
             4.6-9.2
    0019  20 Jul  (similar to above)
                             Latest imagery at 2333 on 19 July.
                                           N                -
    0653, 19 Aug  PIREP      Possible smoke plume at 0438; scattered cloud in
    0812                     area.
              10.7                         N                Y
    0944  20 Aug  AIREP      Smoke plume at 0427; satellite imagery mostly
                             clear of cloud shows a weak plume extending SSE
                             56-74 km.
               7.3                         Y                N
    0938  21 Aug             Satellite imagery lacks clear plume at 0830.
                                           N                -

Activity during February-July 2000. Explosive activity during February 2000 included ash emissions, numerous rockfalls, and a few deep A-type earthquakes (table 4). Plumes of thick white ash were seen to rise up to 400 m above the summit on many occasions. Persistent haze or cloudy weather prevented direct observation throughout most of the month. At night during the week of 8-14 February observers noted a 60-m-high flame. Generally, explosions and rockfalls dominated recorded seismicity.

Table 4. Summary of seismicity at Semeru, 31 January-29 August 2000. * Six days of data, through 15 July. Courtesy of VSI.

    Dates (2000)   Deep    Shallow  Tect. Expl. Avalanche  Tremor  Pyroc-
                  (A-type) (B-type)                                  lastic
                                                                     Flows

    31 Jan-07 Feb    2        3       6     142       49        4      --
    08 Feb-14 Feb    2       --       9     390        5       31      --
    15 Feb-21 Feb    8       --       3     327        9        0      --
    22 Feb-27 Feb    1       --       4     548       11       --      --
    29 Feb-07 Mar  "Seismic activity was relatively similar to last week
                   . . . dominated by explosion and avalanche earthquakes."
    07 Mar-13 Mar   19        5       5     628       38       --       1
    14 Mar-20 Mar    3       --      15     530       18       --      --
    21 Mar-27 Mar    5        4       8     733       26       --      --
    28 Mar-03 Apr    5        4       8     733       26       16      --
    04 Apr-10 Apr    8       --       7     737       45       56       1
    11 Apr-17 Apr    1       --       3     805       50       18      --
    18 Apr-24 Apr   --        1       4     678       45       48      --
    25 Apr-01 May    2       --       4     703       31       17       3
    02 May-08 May   --       13       3     770       46       --       5
    09 May-16 May   --       --       2     535       15       --       4
    17 May-23 May    7        3       1     705       95       --       3
    24 May-30 May  No data available
    31 May-05 Jun  No data available
    06 Jun-12 Jun  No data available
    13 Jun-19 Jun   --       --       7     557       25        7       2
    20 Jun-26 Jun    1        1       4     709       56        4      --
    27 Jun-02 Jul   --        1       6     600       86       15       6
    03 Jul-09 Jul    1       --       6     717       36        9       8
    10 Jul-15 Jul*  --        1       6     557       27        6       8
    17 Jul-23 Jul  No data available
    24 Jul-30 Jul   14        4      18     542       60       --       7
    31 Jul-07 Aug   --       --      --     657       64       --       5
    08 Aug-14 Aug   --       --      --     584       43       --       2
    15 Aug-21 Aug   --       --      --     420       17       --       0
    22 Aug-29 Aug   23        1      21     542       27       --       3

Explosions and lava avalanches continued in March. Clouds and haze often obscured the volcano, but sometimes thick white emissions appeared above the summit to a maximum height of 500 m. Visual activity and seismicity appeared to increase in late March-early April.

During 4-10 April explosions and lava avalanches were still continuing and became stronger. Seismicity also increased significantly; tremor earthquakes took place 56 times, with maximum amplitudes of 3-15 mm. One pyroclastic flow traveled 1,500 m down the Besuk Kembar river. Many observations in clear conditions showed that the ash cloud was thick and white, rising 400-600 m above the summit. Emissions continued the following week, and explosions increased. "Red flames" sometimes appeared at the summit during night observations. Similar activity continued throughout April. The number of pyroclastic flows increased in late April, and continued at a typical rate of 2-7 per week for the next few months (table 4). On 30 April at 0743, from a location 15 km NNW of Semeru, a pyroclastic flow was observed travelling 800 m down the SSW flank.

Ashfall occurred at the Semeru Volcano Observatory during the week of 2-8 May, when five pyroclastic flows were recorded. Seismicity decreased again, but "red flame" was still seen at night and plumes rose as high as 600 m through 23 May.

Explosive activity was continuing in the second half of June; observers noted white-gray plumes ~600 m above the summit. Pyroclastic flows that reached maximum distances of ~2.5-3 km were reported on 1-2, 4, 10, and 15 July.

Observations on 2 May 2000. John Seach and Geoff Mackley made observations during a 3-hour summit stay on 2 May 2000. During the climb from Ranu Pani village in the N, ash deposits were observed to cover vegetation at a distance of 10 km from the volcano. The bottom third of the cone was vegetated, and zones of mass-wasting had sliced away 20- m-wide sections of forest. The top two-thirds of the cone consisted of ash, cinders, and blocks up to 1.5 m in diameter. There were areas of deep erosion and the risk of rockfalls posed a hazard to climbers.

The summit area (Mahameru) lay covered by ash and baseball-sized blocks with a density of 50/m2. A 20-m-wide, 60-m-deep, W-sloping valley separated Mahameru from the active Jonggring Seloko crater, but they are joined by a ridge. The highest N rim of the crater was approximately 30 m below the summit peak. A 2-m-diameter block was located 15 m below the summit on the wall of the valley.

Between 0725 and 1010, 13 eruptive events were observed. During this interval the N rim of Jonggring could not be approached because of the intermittent rain of blocks falling outside the crater and into the valley 50 m from the crater. Two vents produced short-lived Vulcanian eruptions with variable timing and size. Eruptions commenced with degassing, explosions, or the sound of breaking rock, followed by falling bombs and brown ash emission. The explosions were relatively quiet and not accompanied by groundshaking. Brown ash clouds rose to 600 m above the vent and drifted SE. The plume detached from the summit before the next eruption began. Steam emission occurred between eruptions.

Observations on 14 July 2000. Volcanologists on an International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) field trip in east Java observed eruptions of Semeru from an observation point on the N rim of the Sand Sea caldera at Bromo (figure 10). Eruption plumes became visible just before sunrise. Gray ash-and-steam plumes rose a few hundred meters and drifted out over the ocean. Multiple plumes from earlier eruptions were visible downwind. Eruptions lasted up to 2 minutes, and occurred at intervals of between 5 and 30 minutes during the approximately 2 hours of observations. One explosion event was quickly followed by another explosion, apparently from a second location within the crater. Plumes were frequently seen during the next two days from other points around the volcano.

Figure 10. Photograph taken just after sunrise on 14 July 2000 showing an ash eruption from Semeru (upper right) and a steam plume rising from Bromo (lower left). The cone in the lower right is Batok, another young cone within the Sand Sea caldera of the Bromo-Tengger volcanic complex. Note the extensive ash cover on the upper part of Semeru. View is towards the S. Courtesy of Ed Venzke, Smithsonian Institution.

Explosion on 27 July 2000. At approximately 0706 on the morning of 27 July an explosion resulted in two deaths and injuries to five other volcanologists near the NE rim of the active summit crater Jonggring Seloko (see map in BGVN 17:10). The group consisted of a five-member Semeru evaluation team of the Volcanological Survey of Indonesia (VSI), four local porters, and foreign scientists who had attended the IAVCEI conference in Bali the previous week. The fatalities and injuries were caused by impacts and burns from ballistic clasts. These originated from the second of two closely spaced explosions from separate vents that ejected material out to a few hundred meters. Both fatalities were VSI staff members: Asep Wildan was the team leader, and Mukti was a volcano observer from the Semeru Volcano Observatory. Those injured included Suparno, a VSI volcano observer from the Semeru Volcano Observatory, Amit Mushkin from the Hebrew University in Israel, Mike Ramsey from the University of Pittsburgh, and Lee Siebert and Paul Kimberly from the Smithsonian Institution. Kimberly sustained the most serious injuries among the five survivors, including a broken hand, broken arm, and 3rd-degree burns. Following surgeries in Singapore and burn treatments in the United States, Kimberly was released from the hospital in early September.

Continuing activity through August. Visual observations were hindered by bad weather the first week of August. Activity generally decreased through 22 August. White to light-brown ash clouds rising to about 600 m in height were frequently seen during this period. Seismicity increased again in late August, and on 25 and 27 August three pyroclastic flows were recorded. Thin white-gray ash plumes rose ~600 m.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: isya@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); John Seach, P.O. Box 16, Chatsworth Island, NSW 2469, Australia; Ed Venzke, Global Volcanism Program, Smithsonian Institution, Washington DC 20560-0119, USA.
Download or Cite this Report

08/2001 (BGVN 26:08) Continuous seismic activity, plumes to ~11.6 km

From August 2000 through August 2001, activity at Semeru was characterized by continuous seismic activity and ash-and-steam plumes of varying heights above the summit. The Alert Level at Semeru remained at level 2 (on a scale of 1-4) throughout the report period.

The Darwin Volcanic Ash Advisory Center (VAAC) reported volcanic ash plumes and clouds on several occasions throughout the year (table 5). The plumes ranged from ~4.6 to ~11.6 km altitude, and moved mainly SSE. On 8 July at 1503 a SE-drifting ash plume rose to ~2.5 km above the volcano. Ground-based reports prior to the eruption revealed that each day during 18-24 June Semeru emitted ash to ~0.6 km above the volcano.

Table 5. Summary of Volcanic Ash Advisories from the Darwin VAAC issued between August 2000 and August 2001. Note that heights are given in altitude. Semeru's summit lies at 3,767 m above sea level. Information sources include air reports (for example, routed via airlines, AIREPS), pilot reports (PIREPS), satellite data, and reports from ground observations), and information from the Meteorological and Geophysical Agency of Indonesia. Source date was provided by the Darwin VAAC.

    Date     Time   Source   Comment

    19 Aug   0653   PIREPS   Possible smoke plume observed extending to ~10.6 km and moving S to SE
    19 Aug   0812   PIREPS   Possible smoke plume extending to ~4.6 km
    20 Aug   0944   AIREP    Smoke plume observed extending to ~7.3 km
    21 Aug   0938   AIREP    Smoke plume observed extending to ~7.3 km
    14 Sep   1135   AIREP    Stationary smoke plume at ~6 km
    10 Oct   0333   AIREP    Volcanic ash cloud at ~6 km and ascending
    10 Oct   0433   AIREP    Volcanic ash cloud at ~6 km and ascending
    10 Oct   1030   AIREP    Volcanic ash cloud at ~6 km and ascending
    11 Oct   0216   AIREP    Volcanic ash cloud at ~6 km and ascending
    11 Oct   0435   AIREP    Volcanic ash cloud at ~6 km, intermittent discharge extending to a maximum of 30 NM.
    11 Oct   0528   AIREP    Volcanic ash cloud at ~6 km, intermittent discharge extending to a maximum of 30 NM.
    11 Oct   0925   AIREP    Volcanic ash cloud at ~6 km, intermittent discharge extending to a maximum of 30 NM.
    13 Oct   0426   AIREP    Volcanic ash cloud at ~6 to ~7.6 km drifting SW
    27 Oct   0215   AIREP    Volcanic ash cloud at ~7.6 km lasting for ~10 minutes
    30 Oct   1055   AIREP    Volcanic ash cloud at ~6 km
    11 Dec   0508   AIREP    Volcanic ash to ~7.6 km
    08 Jul   0929   AIREP    Ash plume reported to ~6 km drifting SE
    09 Jul   0857   AIREP    Ash plume to ~6 km drifting SE
    09 Jul   2355   AIREP    Volcanic ash at ~11.6 km
    09 Jul   0857   AIREP    Ash plume reported to ~6 km drifting SE

Explosion earthquakes dominated the seismicity (table 6), and pyroclastic flows occurred 17 times between 31 July 2000 and 15 July 2001. The Volcanological Survey of Indonesia (VSI) reported that a significant change in seismic activity occurred during 3-9 October 2000, when the number of explosion earthquakes increased to more than 700. A pyroclastic flow that reached the Kembar Besuki river, as far as 2,500 m from the summit, occurred on 2 October.

Table 6. Summary of seismicity at Semeru, 31 July 2000-15 July 2001. Ash plume heights are distances above the summit unless otherwise noted. Courtesy of the Volcanic Survey of Indonesia (VSI).

    Date                              Earthquakes

                    Deep       Shallow    Explosion   Avalanche   Tectonic
                    Volcanic   Volcanic
                    (A-type)   (B-type)

    31 Jul-07 Aug       4          5         657          64         22
      Five pyroclastic flows. Five pyroclastic-flow earthquakes. Four tremor events.
    08 Aug-14 Aug       5          4         584          43         13
      Two pyroclastic flows; ash plume ~600 m. Two tremor events.
    15 Aug-21 Aug       2         --         420          17          5
      Ash plume ~600 m.
    22 Aug-29 Aug      23          1         542          27         21
      Ash plume ~600 m. Three pyroclastic-flow earthquakes.
    29 Aug-04 Sep      23          1         542          27         21
      Ash cloud ~600 m. Three pyroclastic-flow earthquakes.
    05 Sep-11 Sep      --          2         594           8         --
      Ashfall (105 events); white cloud to ~700 m.
    12 Sep-18 Sep      --         --         623          --         --
      Three pyroclastic flows; ashfall (72 events); ash plume to ~600 m. Two tremor events.
    19 Sep-25 Sep      --          3         556          98         16
      Ash plume to ~600 m.
    26 Sep-2 Oct        2          2         582          19          1
      Thin white ash plume. One pyroclastic-flow earthquake. 79 tremor events.
    03 Oct-09 Oct       1          1         707          80         14
      One pyroclastic flow.
    10 Oct-16 Oct       1          3         592          41         13
      One pyroclastic flow; ash plume to ~600 m.
    17 Oct-23 Oct       3         --         607          25         --
    24 Oct-30 Oct      42          1         592          22          7
      Volcano covered by haze. Four tremor events.
    31 Oct-6 Nov       16          1         561          48         13
      Ash plume to ~600 m.
    28 Nov-4 Dec        8         --         483          24          2
      Thick white fume 600 m above Jonggring Seloko crater.
    05 Dec-11 Dec       1          1         513          16          6
      Two pyroclastic flows; thick white fume 600 m above Jonggring Seloko crater.
    12 Dec-18 Dec       2         --         598          38          5
      Volcano covered by smog.
    19 Dec-25 Dec      --          1         319          22          2
    26 Dec-1 Jan        1         --         559          98          7
      White-gray ash plume to 600 m.

    2001

    02 Jan-08 Jan       6         --         579          80         10
    09 Feb-15 Feb      29          1         693          80          4
    13 Feb-19 Feb       1         --         519          29          1
      No visual observations because of cloudy weather.
    20 Feb-26 Feb       3         --         702          58          5
      White-thin plume to ~100 m.
    27 Feb-05 Mar      --         --         249          27          2
      White-gray plumes to ~600 m.
    06 Mar-12 Mar       6         --         303          31         --
    12 Mar-18 Mar       4         --         349          10          3
    19 Mar-23 Mar       2         --         259          --          1
    02 Apr-09 Apr      28         --         305         248          3
    09 Apr-15 Apr      --         --         339          51          3
    16 Apr-22 Apr      --         --         550          --         --
    23 Apr-29 Apr      12          1         759         157          4
    30 Apr-06 May      --         --         782          96          7
    07 May-13 May       2         --         670         113          7
    14 May-20 May       1         --         616         143          2
    28 May-03 Jun      --         --         396         115          3
    04 Jun-10 Jun       3         --         430          75          5
    11 Jun-17 Jun       2         --         361          81          4
    18 Jun-24 Jun       8         --         346          62          3
    25 Jun-01 Jul       2         --         331          37          2
    02 Jul-08 Jul      --         --         299          30          6
    09 Jul-15 Jul      --         --         687          57         11

During 27 March-1 April 2001, VSI personnel observed several lava avalanches that traveled to Kembar River valley as far as 750 m S of the summit. No seismic data were available because the seismometers broke on 24 March 2001. They were repaired on 1 April.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: isya@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/).
Download or Cite this Report

06/2002 (BGVN 27:06) Seismicity increases beginning in March 2002; Alert Level increased to 2

Since mid-July 2001, Semeru was at Alert Level 1 (on a scale of 1-4). On 8 March 2002 two pyroclastic flows traveled 2.5 km downslope to the Besuk Kembar river. The same day, tectonic and volcanic earthquakes increased, prompting the Volcanological Survey of Indonesia (VSI) to raise the Alert Level to 2. Tectonic and volcanic earthquakes continued, along with explosions, avalanches, pyroclastic flows, and tremor (table 7). Plumes, sometimes containing ash, were visible reaching up to 500 m above the summit (table 8).

Table 7. Seismicity registered at Semeru during 3 March-16 June 2002. "--" indicates that information was not reported. Courtesy VSI.

    Date (2002)       Deep      Shallow     Explosion    Avalanche
                    volcanic    volcanic

    03 Mar-10 Mar       8           1          479           22
    11 Mar-17 Mar       1           2          444           21
    18 Mar-24 Mar       2          --          514           10
    25 Mar-31 Mar       9           6          302          171
    01 Apr-07 Apr      26           2          415          278
    08 Apr-14 Apr       9          --          509          141
    15 Apr-21 Apr      16           4          791          194
    22 Apr-28 Apr       6           0          585           64
    29 Apr-05 May       0           0          664           52
    06 May-12 May       5           0          783           62
    13 May-19 May       1           0          575          146
    20 May-26 May      --          --           --           --
    27 May-02 Jun       2           1          556           90
    03 Jun-09 Jun       2          --          556           45
    10 Jun-16 Jun       2          --          637           31

    Date (2002)       Far        Local      Pyroclastic    Tremor     Far
                    tectonic    tectonic       flow                  tremor

    03 Mar-10 Mar      9           2             2           --        --
    11 Mar-17 Mar      3          --            --            3        --
    18 Mar-24 Mar     14           1            --           --        --
    25 Mar-31 Mar     15           1            --            2        --
    01 Apr-07 Apr     26          --            --           --        --
    08 Apr-14 Apr     18           3            --            1        --
    15 Apr-21 Apr      9          --            --           --        --
    22 Apr-28 Apr     --           3             0            5        14
    29 Apr-05 May     --           0             0            3        14
    06 May-12 May     --           0             0            0        15
    13 May-19 May     --           0             0            0        13
    20 May-26 May     --          --            --           --        --
    27 May-02 Jun     20           1            --            2        --
    03 Jun-09 Jun      9          --            --            1        --
    10 Jun-16 Jun      4          --            --           --        --

Table 8. Plumes observed at Semeru during 8 March-16 June 2002. Courtesy VSI.

    Date (2002)             Plume Type                    Plume height
                                                       (above the summit)

    08 March                White-gray                       400 m
    12, 14, and 17 March    White-gray                      300-400 m
    19-23 March             White-gray                     ~300-500 m
    25-31 March             White-gray                      300-500 m
    15-21 April             White-gray, medium pressure      400 m
    22 April-26 May         White-gray, medium pressure      400 m
    10-16 June              White-gray ash                  200-400 m

On 31 March two tremor earthquakes occurred with amplitudes of ~3-17 mm. During mid-April, a tremor earthquake occurred with an amplitude of 0.2 mm. Lava avalanches continued to travel up to 750 m down to Besuk Kembar. Seismic signals thought to indicate local floods registered 15-21 April. Incandescence was observed up to 25 m above the crater rim during 1820-2025 on 18 April. During that time, seismicity was dominated by low-frequency earthquakes, with amplitudes of 2-3 mm. During 27 May-2 June ash explosions produced white-gray plumes that reached ~200-400 m above the summit, while lava avalanches traveled ~100 m away. Semeru remained at Alert Level 2 through at least 16 June 2002.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: isya@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

09/2002 (BGVN 27:09) Higher-than-normal seismic and explosive activity during June-September 2002

During 17 June-8 September, activity at Semeru was higher than normal. Seismicity was dominated by explosion and avalanche earthquakes. Volcanic and tectonic earthquakes also occurred, along with occasional tremor episodes (table 9). During June and July, and on 6 August, when fog did not obscure the view, observers reported that lava avalanches traveled toward Besuk Kembar river at distances of ~750 m from the crater rim. At times during July explosions produced white ash plumes that reached 300-500 m above the crater. During mid-August to early September, a white-gray ash plume rose 400-500 m above the crater. On 8 September at 1947 an ash explosion ejected glowing material ~150 m toward the upper stream of Besuk Kembar river. Semeru remained at Alert Level 2.

Table 9. Earthquakes and tremor registered at Semeru during 17 June-8 September 2002. Courtesy VSI.

    Date (2002)    Volcanic  Explosion  Avalanche    Tremor       Far
                                                   (max. amp.)  tectonic

    17 Jun-23 Jun     --        670         75         --           6
    24 Jun-30 Jun     --        782         83          1          11
    01 Jul-07 Jul     --        714         76          1          11
    08 Jul-14 Jul     --        898         77         --           8
    15 Jul-21 Jul     --        670         83         --           7
    22 Jul-28 Jul  4 B-type     696         88      3 (1-4 mm)      7
    29 Jul-04 Aug     --        744         92      (1-4 mm)        6
    05 Aug-11 Aug  1 B-type     668        106         --          12
                                                                (1 local
                                                                tectonic)
    12 Aug-18 Aug     --        696         67         --           2
    19 Aug-25 Aug  2 A-type     734        108         --          15
    26 Aug-01 Sep  1 B-type     845        115         --          16
    02 Sep-08 Sep  1 A-type     640         57         --           2

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: isya@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

12/2002 (BGVN 27:12) Elevated explosive activity continues; evacuation on 30 December 2002

Higher-than-normal seismic and explosive activity occurred at Semeru during June-September 2002 (BGVN 27:09). During 9 September-29 December, activity continued to be higher than normal. Seismicity was dominated by explosions and avalanche earthquakes (table 10). Throughout the report period, a white-gray ash plume rose 400-500 m high above the Jonggring Seloko crater rim. There were eight explosions on 23 December, one explosion on 25 December, seven explosions on 26 December, eight explosions on 27 December, and another seven explosions on 29 December.

Table 10. Earthquakes recorded at Semeru during 9 September 2002-1 January 2003. "*" indicates that the report was part of a special report issued by VSI and may break the sequence of weekly reports. Courtesy VSI.

    Date              A-type      B-type     Explosion    Avalanche
    (2002-2003)      volcanic    volcanic

    09 Sep-15 Sep        1          --          640          57
    16 Sep-22 Sep        1          --          527          32
    23 Sep-29 Sep        0          --          483          24
    30 Sep-06 Oct        0          --          602          13
    07 Oct-13 Oct       --          --          548          27
    14 Oct-20 Oct        1          --          493          20
    21 Oct-27 Oct       --           1          561          27
    28 Oct-03 Nov       --          --          430           3
    04 Nov-10 Nov       --          --          528          34
    11 Nov-18 Nov       --          --          273          27
    02 Dec-08 Dec       --          --          474          13
    09 Dec-15 Dec       --          --          513           6
    16 Dec-22 Dec       --          --          606           6
    03 Dec-16 Dec*       0           0          967          19
    17 Dec-30 Dec*       0           1         1085          49
    23 Dec-29 Dec       --           1          479          43
    31 Dec 2002*        --          --       83 (47 mm    30 (2 mm
                                             max. amp.)   max. amp.)
    01 Jan 2003*        --       3 (2-6 mm   88 (36 mm    18 (4 mm
                                 amp., 11-   max. amp.)   max. amp.)
                                 12 sec.
                                 duration)

    Date             Tremor    Tectonic    Pyroclastic   Flood/lahar
    (2002-2003)                               flow

    09 Sep-15 Sep       0          2           --            --
    16 Sep-22 Sep       4          6           --            --
    23 Sep-29 Sep      13          2           --            --
    30 Sep-06 Oct       1          7           --            --
    07 Oct-13 Oct       1          4           --            --
    14 Oct-20 Oct       2          4           --            --
    21 Oct-27 Oct      --          6           --            --
    28 Oct-03 Nov      --         --           --            --
    04 Nov-10 Nov       2          2           --            --
    11 Nov-18 Nov      --          1           --            --
    02 Dec-08 Dec       7          3            3            --
    09 Dec-15 Dec       1          1            1            --
    16 Dec-22 Dec       1         --            1            --
    03 Dec-16 Dec*      8          3            4             0
    17 Dec-30 Dec*      2          6            6             3
    23 Dec-29 Dec       2          6            3             4
    31 Dec 2002*        1         --           --             1
                    (3 mm amp., 80-sec. duration)
    01 Jan 2003*        1         --           --            --
                    (1 mm max. Amp., 60 sec. duration)

On 25 December, a pyroclastic flow traveled 2.5 km and entered the Besuk Kembar river. On 27 December lava avalanches traveled 250 m toward Besuk Kembar. On 29 December a 5 km pyroclastic flow occurred. The same day during 1700-2015 a lahar flowed along Besuk Kembar closer to Supit village. Early on the morning of 30 December residents of Supit village were evacuated. The same day at 0720 a pyroclastic flow traveled 2.0 km toward Besuk Kembar and at 1000 a pyroclastic flow traveled 4.0 km, approaching Supit village. Semeru remained at Alert Level 2 (on a scale of 1-4).

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

04/2003 (BGVN 28:04) Continued ash explosions, with frequent lava avalanches and pyroclastic flows

At Semeru, the end of December 2002 was characterized by high numbers of explosions and pyroclastic flows (BGVN 27:12). The 29 December pyroclastic flow at Besuk Bang (figures 11 and 12) traveled ~9 km from the summit. During January through 23 March 2003, the Volcanological Survey of Indonesia (VSI) reported that seismicity was dominated by explosions and avalanches (table 11). A "white-gray ash" column rose 300-700 m above the summit. Activity was especially high during 1-12 January, when tens of ash explosions were visually observed per week (figures 13 and 14). Continuous tremor occurred on 8 January, with an amplitude of 11-12 mm. The Alert level remained at 2.

Figure 11. The edge of 29 December 2002 Semeru pyroclastic-flow deposit at Besuk Bang in January 2003. This pyroclastic flow extended ~ 9 km from the summit. Courtesy of I. Mulyana, H. Triastuty, M. Hendrasto, and MA Purbawinata (VSI).
Figure 12. Boulders from the Semeru pyroclastic-flow deposit at Besuk Bang around December 2002-January 2003. Courtesy of I. Mulyana, H. Triastuty, M. Hendrasto, and MA Purbawinata (VSI).

Table 11. Summary of weekly seismicity at Semeru during 1 January-23 March 2003. Courtesy VSI.

    Date(2003)       Deep    Shallow   Explosion  Avalanches    Tremor     Pyroclastic
                   volcanic  volcanic   events                earthquakes     flows
                   (A-type)  (B-type)

    01 Jan-05 Jan     --         4        354         89           7            0
    06 Jan-12 Jan     --        --        382         84          38            1
    13 Jan-19 Jan     --         1        554         89           7            0
    20 Jan-26 Jan      1         2        641         50          15            0
    27 Jan-02 Feb     18        --        739         84           9            3
    03 Feb-09 Feb      2        --        777         58           9           14
    10 Feb-16 Feb      3         4        641         53          13            5
    17 Feb-23 Feb      4         9        700        105          10            9
    24 Feb-02 Mar      6        --        629         33           8           10
    03 Mar-09 Mar     --         4        794         18           4            0
    10 Mar-16 Mar      2        --        550         89          20           21
    17 Mar-23 Mar     --        --        563         57           9           13
Figure 13. View toward the summit of Semeru looking NW from G. Sawur (observatory post) around December 2002-January 2003. Courtesy of I. Mulyana, H. Triastuty, M. Hendrasto, and MA Purbawinata (VSI).
Figure 14. Eruptive plumes rise from two different vents at the summit of Semeru around December 2002-January 2003. Courtesy of I. Mulyana, H. Triastuty, M. Hendrasto, and MA Purbawinata (VSI).

Lava avalanches in January 2003 extended up to 750 m from the crater rim and sometimes entered the Besuk Kembar river. One pyroclastic flow traveled 1,500 m and also entered Besuk Kembar. Pyroclastic flows were more numerous in February, travelling between 2.5 and 4 km from the summit into the Besuk Bang drainage. Lava avalanches were continuous during 17-23 February towards Besuk Kambar. Several pyroclastic flows in March moved toward Besuk Bang (up to 4 km long) and Besuk Kembar (up to 2 km long).

Infrared satellite data, January 2001-March 2003. Between January 2001 and March 2003, MODIS detected quasi-continuous thermal alerts at Semeru (figure 15). During January 2001-March 2002, the anomalies were characterized by 1-2 alert-pixels with a maximum alert ratio of -0.567 (4 May 2001). The Darwin VAAC reported ash plumes and clouds on several occasions throughout this period, and VSI reported numerous seismic events representing explosions and other phenomena (BGVN 26:08).

Figure 15. MODIS thermal alerts on Semeru during January 2001-March 2003. Thermal alerts collated by Diego Coppola and David Rothery; data courtesy of the Hawaii Institute of Geophysics and Planetology's MODIS Thermal Alert Team.

From April 2002 until the end of the year, MODIS thermal alerts for Semeru increased in frequency and magnitude. This period was characterized by continuous explosions, avalanches and pyroclastic flows, and is related to seismicity increases beginning in March 2002 that prompted VSI to raise the Alert Level to 2 (BGVN 27:06). Thermal alerts reached a maximum amplitude on 16 August (two alert pixels with a maximum alert ratio of -0.364) and 1 September (one alert pixel with alert ratio of -0.389). VSI reported that seismic activity was higher than normal during June-September 2002 (BGVN 27:09), and the explosions produced plumes that reached 300-500 m above the crater. Observers reported that lava avalanches traveled toward the Besuk Kembar river to distances of ~750 m from the crater rim, and an ash explosion ejected glowing material ~150 m toward the upper Besuk Kembar drainage. Center coordinates of alert pixels were concentrated in four adjacent pixels close to Semeru's summit, especially on the S side.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/); Diego Coppola and David A. Rothery, Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA, UK (Email: d.coppola@open.ac.uk, d.a.rothery@open.ac.uk). Thermal alerts courtesy of the HIGP MODIS Thermal Alerts Team (URL: http://modis.higp.hawaii.edu/).
Download or Cite this Report

07/2003 (BGVN 28:07) Ash plumes, pyroclastic flows, and high seismicity continue through June

According to the Volcanological Survey of Indonesia (VSI), activity during 24 March-29 June 2003 was continually at a high level. Explosions produced white-gray ash plumes several times per week that rose 300-600 m over the summit. Pyroclastic flows on 27 March had a run-out distance of 3,750 m toward Besuk Bang. More pyroclastic-flow events on 14 and 18 April traveled toward Besuk Bang (3,500 m) and Besuk Kembar (2,500 m). On 11 May a pyroclastic flow entered Besuk Kembar and extended 1,500 m. Seismographs continually recorded earthquake activity (table 12). The hazard status remained at Level 2 (on a scale of 1-4) throughout the report period.

Table 12. Seismicity at Semeru, 24 March-29 June 2003. Courtesy of VSI.

    Date (2003)    Explosions  Avalanches  Tremor  Other      Tectonic
                                           Events            Earthquakes

    24 Mar-30 Mar     794         48         17    1 flood;       6
                                                   12 PF's
    31 Mar-06 Apr     738         28         12    2 shallow;     6
                                                   2 PF
    07 Apr-13 Apr     698         33         11    7 PF           6
    14 Apr-20 Apr     697         70         20    12 PF          7
    21 Apr-27 Apr     713         82         16    1 deep volc    9
    28 Apr-04 May     651         36         31    1 deep volc    2
    05 May-11 May     846         37         27    2 shallow      5
                                                    volc; 1 PF
    12 May-18 May     730         41         38    1 shallow      3
                                                    volc
    19 May-25 May     748         17         17    --             8
    26 May-01 Jun     585         27         26    --             8
    02 Jun-08 Jun     758         29         24    --             4
    09 Jun-15 Jun     600         27         63    2 deep volc   13
    16 Jun-22 Jun     711         20         13    1 shallow      8
                                                    volc
    23 Jun-29 Jun     838         33         --    -              4

Information Contacts: Dali Ahmad and Nia Haerani, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

09/2003 (BGVN 28:09) Frequent ash explosions continue through September

Volcanic activity at Semeru between 30 June and 28 September remained at high levels. Except for the middle two weeks of July, ash explosions were reported several times every week, producing white-gray plumes that rose 400-500 m above the summit. Recorded seismic data (table 13) reflected this continued activity, with between 447 and 804 explosion events weekly (~ 88 per day on average over this 90-day period). Avalanche events, tremor, tectonic, deep-volcanic, shallow-volcanic, and flood-related seismicity were also recorded. A pilot report from Qantas noted a plume to twice the height of the volcano (~ 7.2 km altitude) on 9 September that was drifting S. The hazard status remained at Alert Level 2 throughout the report period.

Table 13. Seismicity at Semeru, 30 June-28 September 2003. Courtesy of VSI.

    Date (2003)    Explosion    Avalanche    Tremor     Other      Tectonic

    30 Jun-06 Jul     611           7           6        --            7
    07 Jul-13 Jul     615          10          18      2 deep          9
    14 Jul-20 Jul     579          19           1        --            8
    21 Jul-27 Jul     529          11           7        --           10
    28 Jul-03 Aug     447          21           5        --            6
    04 Aug-10 Aug     499          20          10      1 shallow       5
    11 Aug-17 Aug     550           8          16        --            6
    18 Aug-24 Aug     516          13           2      1 shallow      10
    25 Aug-31 Aug     804          11           1        --            7
    01 Sep-07 Sep     735          12           0         0            6
    08 Sep-14 Sep     699          30           1      1 flood         5
    15 Sep-21 Sep     731          11           5         0            8
    22 Sep-28 Sep     636          20           9         0            4

Information Contacts: Dali Ahmad and Nia Haerani, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom. gov.au/info/vaac/).
Download or Cite this Report

10/2003 (BGVN 28:10) Frequent ash explosions continue through October

Frequent ash explosions at Semeru during 29 September-26 October 2003 produced white-gray ash plumes 400-500 m over the summit. The hazard status remained at Alert Level 2 (on a scale of 1-4) during this time. Although tectonic earthquakes, tremor events, shallow volcanic earthquakes, and avalanches were all detected seismically, the record was dominated by explosions (table 14). Explosions over this 4-week period averaged 95 per day, or one every 15 minutes.

Table 14. Seismicity at Semeru, 29 September-26 October 2003. Four shallow volcanic earthquakes were also detected during 6-12 October. Courtesy of VSI.

    Date (2003)     Explosion   Avalanches   Tremor   Tectonic

    29 Sep-05 Oct      636          20          9         4
    06 Oct-12 Oct      567          10         --         7
    13 Oct-19 Oct      687          19         22         4
    20 Oct-26 Oct      768          16          3        11

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

12/2003 (BGVN 28:12) November volcanism includes 70-90 explosions per day

Volcanic activity at Semeru continued at a high level over the period 27 October-30 November, with a white-grey ash plume 300-600 m above the crater. A summary of seismicity (table 15) shows a ~ 20 percent reduction in the number of explosions compared to the previous four weekly intervals (BGVN 28:10). Semeru's hazard status remained at alert level 2 (on a scale of 1-4).

Table 15. Seismicity recorded at Semeru, 27 October-30 November. Courtesy of VSI.

    Dates (2003)    Volcanic A    Tremor    Tectonic    Explosion    Avalanche

    27 Oct-02 Nov        1          --         --           --            2
    03 Nov-09 Nov       22          15         11           41            8
    10 Nov-16 Nov        4          13         12            3            7
    17 Nov-23 Nov      565         585        524          596          568
    24 Nov-30 Nov       11          17         14           15            7

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Vulcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).
Download or Cite this Report

06/2004 (BGVN 29:06) Persistent seismicity and ash plumes during April-June 2004

According to the Volcanological Survey of Indonesia (VSI), Semeru remained at Alert Level II (on a scale of 1-4) for the entire report period of April-June 2004. VSI characterizes Level II as "increasing seismic activity and other volcanic events and visual changes around the crater" but also states that this definition implies "no eruption is imminent." A pilot reported an 18 June ash plume rising to 6 km.

During the week of 12-18 April, tectonic earthquakes and tremor increased. Plumes sometimes containing ash were observed reaching heights of 110-400 m above the summit. Other seismic signals (including those from explosions, avalanches, and tremor) also continued. The Darwin VAAC reported that an ash plume was visible in satellite imagery on 18 April, reaching a height of ~ 4.5 km and extending ~ 90 km NW.

During 19-25 April, white-gray ash plumes were observed reaching heights of 100-400 m above the summit. The Darwin VAAC reported that an ash plume was visible in satellite imagery on 20 April, reaching a height of ~ 4.5 km and extending ~ 75 km SSE. Another plume on 21 April rose to ~ 4.6 km altitude and drifted ESE. Increases occurred in tremor as well as tectonic earthquakes, shallow-volcanic earthquakes, and explosion earthquakes. The number of avalanche signals decreased (table 16).

Table 16. Summary of seismicity at Semeru during 12 April-4 July 2004. The highest values in several categories occured during 7-13 June. Courtesy of VSI.

    Dates (2004)    Volcanic-A     Volcanic-B    Tremor     Tectonic      Explosion    Avalanche
                    earthquakes    earthquakes             earthquakes     signals      signals

    12 Apr-18 Apr        0              0          25           5            508          10
    19 Apr-25 Apr        0              3          38          11            638           8
    26 Apr-02 May        1              2          19           7            736          12
    03 May-09 May        1              0          22           7            853           9
    07 Jun-13 Jun        2              9          34          15            902          22
    14 Jun-20 Jun        1              0          19          14            630          11
    21 Jun-27 Jun        4              5          39           8            860          14
    28 Jun-04 Jul        0              1          27          16            805          12

During the week of 26 April-2 May, explosion and avalanche signals increased, with continuing tremor, and volcanic earthquakes. Tremor and explosion signals increased, but avalanche signals decreased, during the week of 3-9 May. White-gray ash plumes were observed reaching heights of 300-400 m above the summit during both weeks. The Darwin VAAC reported that a thin ash plume from Semeru was visible on satellite imagery on 23 May around 0625; it reached a height of ~ 4.3 km altitude and extended ~ 110 km SSE.

An ash plume from Semeru was reported on 4 June rising to ~ 4.5 km altitude During the week of 7-13 June, a white-gray plume was observed on a clear day rising to heights of 300-400 m above the summit. Seismographs recorded an increasing number of volcanic, tectonic, and tremor earthquakes, and explosion and avalanche signals compared to the previous week. Indeed, that week was the most seismically active on the basis of most parameters, with more than 900 explosion signals and more volcanic earthquakes, tremor, and avalanche signals than any other week (table 16).

Visual observation was difficult during 14-20 June due to fog, although a white-gray plume was observed on 18 June, rising to heights of 500-600 m above the summit. Based on a pilot's report, the Darwin VAAC reported that on 18 June an ash cloud from Semeru was visible at a height of ~ 6 km altitude, extending ~ 40 km E; this was the highest recorded ash cloud during the report interval. No ash was visible on satellite imagery. The number of volcanic, tremor, and tectonic earthquakes, and explosion and avalanche signals decreased from the previous week.

Foggy weather made visual observation difficult again during the week of 21-27 June. On one clear day a white-gray ash explosion was observed rising 500-600 m above the summit. Seismographs recorded volcanic, tremor, and tectonic earthquakes, and explosion and avalanche signals. Seismicity had generally increased, except for tectonic earthquakes, compared to the previous week.

During the week of 28 June-4 July, visual observations of the summit were again difficult because of cloud cover, but a gray ash plume was observed rising to 500-600 m above the summit on one clear day. Seismographs still recorded volcanic, tremor, and tectonic earthquakes, and explosion and avalanche signals.

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Vulcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom. gov.au/info/vaac/).
Download or Cite this Report

03/2007 (BGVN 32:03) Minor ash eruptions continue into February 2007

Our previous report (BGVN 29:06) covered activity at Semeru through 4 July 2004. This report, compiled chiefly from reports from the Center of Volcanology and Geological Hazard Management (CVGHM) and the Darwin Volcanic Ash Advisory Centre (Darwin VAAC), discusses subsequent activity into early 2007. Minor eruptions with the highest reported plumes reaching 7.6 km altitude continued from mid-2006 through April 2007. During mid-2006 to May 2007 there were also numerous thermal anomalies. The thermal data were captured by MODIS satellite sensors and presented on the MODVOLC system.

On 9 March 2006, the CVGHM reported "ash rain" fell in the vicinity of Semeru. An eruption associated with earthquakes was photographed on 31 October 2006 (figure 16). On April 22, based on information from a significant meteorological notice and satellite observations the Darwin VAAC reported the first of a series of eruptions. Plumes rose to an altitude of ~ 4 km. Table 17 summarizes reported ash plume eruptions at Semeru through February 2007.

Figure 16. Photograph showing a Semeru ash explosion on 31 October 2006. Courtesy CVGHM.

Table 17. Summary of reported ash plumes emitted from Semeru, July 2004 to February 2007. Courtesy of CVGHM and the Darwin VAAC.

    Date                Plume       Plume        Comments
                     Height (km)    Drift

    18 Jul 2004         3            NW          pilot report
    5-10 Aug 2004       7.6 max      --          pilots' reports of ash clouds
    10 Aug 2004         6.1          --          ash plume
    24 Aug 2004         --           WSW         thin plume
    25 Aug 2004         --           WSW         thin plume, no ash visible
    21 May 2005         4.6          S,
                                   then SSE
    25 May 2005         --           --          small plume reported by Darwin VAAC
    08-14 Mar 2006      --           --          "ash rain" reported by CVGHM
    22 Apr 2006         4            --          based on significant meteorological notice,
                                                   Darwin VAAC reported an eruption that
                                                   generated plume (not visible on satellite
                                                   imagery)
    10-16 May 2006      6.1          --
    04 Jun 2006         --           --          pilot reported multiple minor eruptions
    05-06 Jun 2006      --           --          small ash plumes
    06, 12 Jun 2006     --           --          small ash plumes
    11, 13 Jun 2006     --           --          minor ash/steam plumes
    14 Jun 2006         6.1          --          pilot observation 
    15, 17, 18          --           --          small ash plumes
      Jun 2006
    25 Jun 2006         5.5          --
    29 Jun 2006         ?            SE
    10 Jul 2006         5.5          --
    14 Jul 2006         ?            SE
    17 Jul 2006         4.3          --
    18, 21, 24 Jul 2006 4.3 (max)    --
    24-25, 31 Jul 2006    ?          --          small plumes visible 
    02 Aug 2006         5.2          --
    25 Aug 2006         --           --          ash plumes visible
    15 Sep 2006         4.3          W
    20-21 Sep 2006    11; 4.9        SW          90 km W
    18 Oct 2006         4.6          --
    25-26 Oct 2006      7.6          W
    30 Oct 2006         --           --          ash/steam emissions
    22 Nov 2006         7.6          S           incandescent material fell in all directions
                                                   within 200 m of plume
    24 Nov 2006         4.4          --
    21 Dec 2006         4.3          --
    10-11 Feb 2007      --           --          ashfall 35 km E

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (http://hotspot.higp.hawaii.edu/); Agence France-Presse. (AFP) (http://www.afp.com/english/home/).
Download or Cite this Report

05/2009 (BGVN 34:05) Many ash plumes and some pyroclastic flows during February 2007-March 2009

Our last report (BGVN 32:03) covered through October 2006 in terms of CVGHM reporting and through February 2007 in terms of Darwin VAAC reporting. As has been the case for decades, Semeru's eruptions continued and were ongoing through this reporting interval, February 2007-March 2009. During the reporting interval, ash plumes were periodically observed over the summit at low altitudes of 3.7-4.6 km. Taller plumes, when they occurred, are noted below. There were several cases of plumes over 6 km altitude and as tall as ~ 7.6 km altitude. Pyroclastic flows ran out to distances as great as 3 km (table 18).

Table 18. Compilation of data on Semeru during February 2007-March 2009. Courtesy of CVGHM.

    Date              Plume height and    Seismicity and
                      drift direction     Observations

    10-11 Feb 2007    E                   --
    03-05 May 2007    4.6 km; SW          --
    25 May 2007       4.6 km; W           --
    18-25 Jun 2007    4.2 km              --
    06 Aug 2007       6.1 km              --
    22 Sep 2007       7.3 km              --
    31 Oct 2007       --                  Eruption heard 17 km away
    21 Apr 2008       6.1 km              --
    15, 17-19,        --                  Increased seismicity. Pyroclastic flows up to 500-3000
       21 May 2008                          m from the crater. On 21 May, incandescent ejections.
    22 May 2008       --                  Fewer pyroclastic flows and rockfalls; four up to
                                            2.5 km from crater.
    05 Jun 2008       --                  Decline in seismicity.
    07-09 Jul 2008    4.9-7.6 km; SSW     --
    27 Jul 2008       4.3 km              --
    05 Aug 2008       4.0-4.3 km          Plumes sometimes with incandescent tephra.
    07 Aug 2008       4.3 km              Incandescent material ejected from the crater
    21-22 Aug 2008    3.7 km; W           --
    28 Aug 2008       Low-level           --
    31 Aug 2008       4.6 km; SW          --
    09 Sep 2008       4.3 km; SSW         --
    10 Sep 2008       4.3 km              --
    22 Oct 2008       4.3 km              --
    Jan 2009          --                  Average over 100 daily eruptive earthquakes. Four deep
                                            volcanic earthquakes on the 24th.
    Feb 2009          --                  Average of less than 50 eruptive earthquakes/day.
    01 Feb 2009       4.0 km              --
    21 Feb 2009       --                  18 deep volcanic earthquakes.
    03 Mar 2009       --                  5 eruptive earthquakes.
    06 Mar 2009       3.7 km              0010 local time (see text)
    06, 12 Mar 2009   --                  Volcanic seismicity had a maximum amplitude reached
                                            +- 34 mm.
    12 Mar 2009       4.5 km              Ash/cinder eruption accompanied by rumbling sounds
                                            lasting ~ 6 minutes
    15 Mar 2009       4.3 km              Eruptive earthquake amplitude +-18 mm. Dense
                                            low-pressure ash-cinder eruption; changing to white
                                            air-blasts, then gradually diminishing.
    16-22 Mar 2009    --                  Averaged eruptive earthquakes around 1-30 daily; max.
                                            amplitudes less than 10 mm.

October 2007. Based on reports from CVGHM, the Darwin VAAC reported that an unconfirmed eruption was heard 17 km away on 31 October 2007 (table 18). No plume was seen in MTSAT-IR satellite imagery. A news report from Antara News on 5 November 2007 ("Ash blankets town near Indonesian volcano") noted that scientists monitoring the volcanoes confirmed Semeru as the source. The news report stated that initially residents thought the thin layer of ash had come from Kelut, a volcano that went to Alert Level 4 (the highest status) on 16 October. The eruption of Kelut, while emitting a large dome into a crater lake, triggered few if any sustained explosions (BGVN 33:03). Ash fell in Blitar, outside a 10 km danger zone around Kelut; Semeru is ~ 90 km away.

On 15, 17-19, and 21 May 2008 ash plumes, rockfall avalanches, and multiple pyroclastic flows were observed, as well as increased seismic activity. At that time, the alert level was raised from 2 to 3. By 22 May pyroclastic flows and rockfall avalanches had declined in frequency, and consequently on 5 June the hazard was lowered to Level 2. During 7-9 July 2008, ash plumes rose to altitudes of 4.9-7.6 km, the tallest of the reporting interval.

From January to mid-February 2009, explosion earthquakes occurred on average 100-150 times a day (table 18). Ash and cinder eruptions from Jonggring Saloko crater took place daily every 15-20 minutes, with plumes reaching altitudes of 3.7-4.3 km. During a ~ 5 minute interval on 6 March 2009 at 0010, a loud boom was followed by a bluish flash of lightning 5-7 seconds in duration.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Saut Simatupang, 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Antara News (URL: http://www.antara.co.id/en/).
Download or Cite this Report

08/2010 (BGVN 35:08) Incandescent rock avalanches travel 750 m, plumes reach 500 m above crater

Continuing eruptions at Semeru through March 2009 included ash plumes and some pyroclastic flows (BGVN 34:05). The Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported in late July 2009 that ash eruptions had gradually ceased and seismicity had decreased. Seismicity increased again during November 2009 through at least February 2010 (table 19).

Table 19. Types and numbers of earthquakes and plumes observed at Semeru during January 2009-February 2010.

    Month       Harmonic     Explosion       Deep      Shallow     Observed       Height
                 tremor     earthquakes    volcanic    volcanic     plumes     above crater

    Jun 2009    See text     See text          ?           ?            ?           ?
    Nov 2009       98          3347            2           ?           95         50-500 m
    Dec 2009      148          3507            1           ?          117        100-200 m
    Jan 2010      313          2693           10           1            6         50-200 m
    Feb 2010      289          2522           16           4           41         50-200 m

Regarding tremor and explosion eruptions in June 2009 (table 19), there were fewer than 15 eruptive earthquakes/tremor events per day. The average during May and June 2009 was much less than average daily number of earthquakes during January 2009.

CVGHM reported that, although inclement weather often prevented visual observations, "smoke" was seen rising 50-500 m above the Jonggring Seloko crater through February 2010. On 5 January 2010 incandescence was observed. During 25-28 February, incandescent rock avalanches traveled as far as 750 m from the crater.

MODVOLC Thermal Alerts. According to MODVOLC data, intermittent thermal alerts have been observed for years near Semeru. During this reporting period (April 2009 through October 2010), multiple hotspots were observed only in 2010, on 20 February, 29 April, 2, 20, and 25 May, 14, 21, and 30 June, 7, 28, and 30 July, 6, 8, 15, and 31 August, and 7 and 30 September.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/).
Download or Cite this Report

04/2012 (BGVN 37:04) Increased seismicity with lava flows and pyroclastic flows during February-April 2012

Semeru is one of the most active volcanoes worldwide and is of special concern because the drainage area is heavily populated. The volcano has a steep canyon that extends from the summit to the SE, which has funneled pyroclastic flows and lahars into populated areas. The decades-long seismicity from Semeru has typically included mildly explosive Strombolian style eruptions, earthquakes and tremor, ash plumes, and occasional pyroclastic flows (BGVN 32:03, 34:05, and 35:08). See the location of Semeru with respect to the regional setting in figure 17.

Figure 17. Index map of Semeru (red triangle) with respect to other Holocene regional volcanoes (black triangles). Courtesy of GVCHM and VDAP.

According to reporting by the Center of Volcanology and Geological Hazard Mitigation (CVGHM) and the USGS Volcano Disaster Assistance Program (VDAP), six large explosions between 1981 and 2002 resulted in many fatalities. They noted that since 1995, pyroclastic flows have been restricted to S drainages such as Kali Kembar; however, a small proportion of recent flows have entered the headwaters of Kali Koboan on the SE, which leads to heavily populated areas, including Sumberrejo and Candipuro (figure 18). This report discusses activity between February 2010 (the end of the previous report) and 2 May 2012.

Figure 18. 2010 map of Semeru and adjacent area, showing drainage channels from the summit and nearby population centers. Note the location of the 2012 lava flows just S and SE of the volcano. The area around the SE quadrant is heavily populated with a Volcano Population Index (VPI10) of 7,000. In previous eruptions, lahars reached as far as 30 km from the summit. Should similar lahars occur in the future, as many as 150,000 more inhabitants along major drainages could be affected. Based in part on a summary of activity by CVGHM and VDAP. Modified from Siswowidjoyo and others (1997) and Thouret and others (2007); VPI10 was calulated using LandScan 2010.

On 4 November 2010, CVGHM reported that from August to October 2010 seismic activity at Semeru had increased, and “smoke” and occasional gas plumes rose 400-500 m above the crater. During September incandescent avalanches traveled 400 m SE into the Besuk Kembar drainage on three occasions. Incandescence from the crater was observed in October. Incandescent avalanches traveled 600 m into Besuk Kembar on 2 November. Two days later, they reached 4 km into the Besuk Kembar and Besuk Bang (S) drainages (figure 18). CVGHM noted that the lava dome in the Jonggring Saloko crater was growing. The Alert Level remained at 2 (on a scale of 1-4).

According to the Darwin Volcanic Ash Advisory Centre (VAAC), during 18-19 November 2010, ash plumes rose to an altitude of 4.6 km and drifted 75-110 km N and NW. Sulfur dioxide gas was detected 75 km SW.

According to Volcano Discovery, the group observed 2-3 small-to-medium ash explosions per day during a photo expedition in May 2011, but noted that activity had increased during the past weeks.

In an account posted online by Volcano Discovery on 15 September 2011, the group visited the volcano and noted that an active lava dome was growing inside the crater and that 3-4 eruptions occurred daily. They inferred that the size and frequency of the eruptions had apparently increased in the past days (figure 19).

Figure 19. Photo of Semeru’s crater on 1 September 2011, with a lava dome. Courtesy of Volcano Discovery.

CVGHM reported that on 29 December 2011, both earthquakes and tremor increased, and dense white-and-gray plumes rose as high as 600 m above the active crater. During January 2012, crater incandescence was observed, and avalanches carried incandescent material 200-400 m away from the crater. According to a 4 January 2012 article in the Jakara Globe, a government official indicated that authorities had closed the trail to the peak of Semeru because of heavy rain and an increased danger of landslides.

On 2 February 2012 a large explosion was reported and incandescent material fell up to 2.5 km from the crater. Tables 20 and 21 indicate the types and numbers of earthquakes and other seismic events reported by CVGHM for February to April 2012. Based on the increased seismic activity and visual observations, CVGHM raised the Alert Level from 2 to 3 on 2 February 2012.

Table 20. Types and numbers of earthquakes and plumes observed at Semeru during February-April 2012. Key to seismic signals variously classified as follows: LD, long-distance volcanic earthquake; Erup, eruptive; Expl, explosive; HTr, harmonic tremor; and PF, pyroclastic flow; “-”, either none detected or data not provided. Courtesy of CVGHM.

Month (2012)    Deep    Shallow    LD    Local    Erup    Expl    HTr    PFFebruary         4         1       61      -       80     2336    116    430March            17        5       60      23      -      1665    610    40April            7         2       44      -       -      3447    66     4

Table 21. Observed Semeru plumes during February-April 2012. Data from CVGHM. (The only other plume noted by the Darwin VAAC between February 2010 and May 2012 was on 18-19 November 2010; this plume was noted earlier in the text). Courtesy of CVGHM.

Month          Number of       Plume height(2012)      observed plumes    above craterFebruary          22            100-500 mMarch             9             100-400 mApril             155           100-500 m

CVGHM reported that during 1-29 February 2012 multiple pyroclastic flows from Semeru traveled 500 and 2,500 m into the Besuk Kembar and Besuk Kobokan rivers (on the S flank), respectively. Government officials set up an exclusion zone on the SE flank where pyroclastic flows had occurred.

During 1 February-30 April 2012, dense gray-to-white plumes rose 100-500 m above Jongring Seloko crater and drifted W and N. Incandescence was visible up to 50 m above the crater during 1 February-31 March. Seismicity decreased toward the end of April, although the lava dome grew that month.

According to a news account (People’s Daily Online) on 1 March 2012, seismic activity had increased from 28 to 38 tremors per day. According to the news account, Dr. Surono, head of CVGHM, stated that the volcano was erupting daily, emitting ash plumes, and tremor occurred every 15-30 minutes. He also noted that the volcanic dome was increasing in size.

According to Volcano Discovery, an expedition leader visiting Semeru observed frequent explosions every few minutes on 27 March 2012, with many powerful enough to eject glowing bombs that produced small glowing avalanches down the S flank.

According to CVGHM and VDAP, a new lava dome started to extrude in late 2011 directly over a dome formed in 2010. The new dome probably will not completely fill the summit crater because it is being drained by two new lava flows, both flowing SE. The longer of the two lava flows extended about 1.9 km from the summit vent. Pyroclastic flows are being generated by collapse of the steep termini of the lava flows, and their deposits extend to 3.2 km from the summit, i.e. 0.7 km from the front shown in figure 18. In addition, the collapsing lava flow fronts are resulting in high levels of avalanche and rockfall activity. According to CVGHM and VDAP, the closest villages in the highest-risk areas on the S and SE flanks are about 10 km from the summit.

On 2 May 2012 CVGHM lowered the Alert Level to 2, but reminded the public not to approach the crater within a 4-km radius.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Volcano Disaster Assistance Program (VDAP), US Geological Survey (USGS), 1300 SE Cardinal Court, Bldg. 10, Suite 100, Vancouver, WA 98683; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac); Jakarta Globe (URL: http://www.thejakartaglobe.com); People’s Daily Online (URL: english.peopledaily.com; Volcano Discovery (URL: http://mobile.volcanodiscovery.com).
Download or Cite this Report

Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises abruptly to 3676 m above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano. Semeru has been in almost continuous eruption since 1967.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1967 Aug 31 2014 Apr 27 (continuing) Confirmed 3 Historical Observations Jonggring Seloko
1950 Jul 23 1964 Dec Confirmed 2 Historical Observations Jonggring Seloko
1946 Oct 29 1947 Jun Confirmed 2 Historical Observations Jonggring Seloko
1946 Feb 1946 May Confirmed 2 Historical Observations Jonggring Seloko
1945 Jun 12 1945 Jun 18 Confirmed 2 Historical Observations Jonggring Seloko
1941 Sep 21 1942 Feb Confirmed 2 Historical Observations ESE flank (1400-1775 m)
1915 ± 1 years Unknown Confirmed 2 Historical Observations
1913 Jun 23 1913 Jun 26 (?) Confirmed 2 Historical Observations Jonggring Seloko
1912 Aug 28 Unknown Confirmed 2 Historical Observations
1911 Nov 8 1911 Dec Confirmed 3 Historical Observations
1910 Nov 16 1911 Feb Confirmed 2 Historical Observations
1909 Sep 1910 Mar 22 Confirmed 2 Historical Observations
1908 Jan 1908 Dec Confirmed 2 Historical Observations
1907 Jul 9 (in or before) Unknown Confirmed 2 Historical Observations
1907 Jan 7 1907 Jan 10 Confirmed 2 Historical Observations
1905 Aug 4 Unknown Confirmed 2 Historical Observations
1904 Jan 2 1904 Jan 16 Confirmed 2 Historical Observations
1903 Mar 26 1903 Jun Confirmed 2 Historical Observations
1901 Jan 29 1901 Jan 30 (in or after) Confirmed 2 Historical Observations
1900 Mar 29 1900 Apr 11 (in or after) Confirmed 2 Historical Observations
1899 Dec Unknown Confirmed 2 Historical Observations
1899 Aug 11 Unknown Confirmed 2 Historical Observations
1899 Jan 17 1899 Mar 31 (?) Confirmed 2 Historical Observations
1898 Feb 23 Unknown Confirmed 2 Historical Observations
1897 Jan 1 1897 Jan 3 Confirmed 2 Historical Observations
1896 May 1896 Jun Confirmed 2 Historical Observations
1895 May 22 1895 Oct 1 Confirmed 2 Historical Observations
1893 Dec 11 1894 Feb Confirmed 2 Historical Observations
1893 Jan 1893 May Confirmed 2 Historical Observations
1892 Mar 1892 Apr Confirmed 2 Historical Observations
1889 Jan 1891 May 31 (in or after) Confirmed 2 Historical Observations
1888 Feb 1888 Oct Confirmed 2 Historical Observations
1887 Aug (?) 1887 Oct 11 Confirmed 2 Historical Observations
1887 Feb 1887 Mar Confirmed 2 Historical Observations
1886 Jan 25 1886 Aug 26 ± 5 days Confirmed 2 Historical Observations
1884 Dec 10 (?) 1885 Sep Confirmed 2 Historical Observations
1879 Unknown Confirmed 2 Historical Observations
1878 Unknown Confirmed 2 Historical Observations
1877 Sep Unknown Confirmed 2 Historical Observations
1877 Apr Unknown Confirmed 2 Historical Observations
1872 Oct 23 1872 Oct 23 Confirmed 2 Historical Observations
1867 Apr 15 ± 5 days 1867 May Confirmed 2 Historical Observations
[ 1866 ] [ Unknown ] Uncertain 2  
1865 Apr 15 ± 5 days Unknown Confirmed 2 Historical Observations
[ 1864 Jul 2 ] [ Unknown ] Discredited    
1860 Apr 1860 Jun Confirmed 2 Historical Observations
1857 Aug 13 1857 Sep Confirmed 2 Historical Observations
1856 Sep 10 Unknown Confirmed 2 Historical Observations
1851 Jan Unknown Confirmed 2 Historical Observations
[ 1849 ] [ Unknown ] Uncertain    
1848 Aug 4 Unknown Confirmed 2 Historical Observations
1848 Feb Unknown Confirmed 2 Historical Observations
1845 Jan 1845 Jul Confirmed 2 Historical Observations
1844 Sep 25 1844 Sep 27 Confirmed 2 Historical Observations
1842 Jan 1842 Mar Confirmed 2 Historical Observations
1838 Jul 1838 Oct 18 Confirmed 2 Historical Observations
1836 Aug 3 1836 Aug 5 Confirmed 2 Historical Observations
1832 Apr 18 Unknown Confirmed 2 Historical Observations
1830 Dec 15 1830 Dec 16 Confirmed 2 Historical Observations
1829 Feb Unknown Confirmed 2 Historical Observations
1818 Nov 8 Unknown Confirmed 2 Historical Observations

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Synonyms

Mahameru | Semeroe | Smeroe | Smiroe | Smeru

Cones

Feature Name Feature Type Elevation Latitude Longitude
Kepolo, Gunung
    Kepala, Gunung
Stratovolcano 3035 m 8° 6' 0" S 112° 56' 0" E
Kukusan Cone
Leker Cone
Papak, Gunung Cone
Totogan Malang Cone

Craters

Feature Name Feature Type Elevation Latitude Longitude
Ajek-Ajek Caldera
Darungan, Ranu
    Daroegan, Ranoe
Maar
Jambangan
    Djembangan
Caldera
Jonggring Seloko
    Djonggring Seloko
Crater 3643 m
Kemmerling Crater
Kumbolo, Ranu Maar
Pakis, Ranu Maar
Pani, Ranu Maar
Regulo, Ranu Maar
An eruption plume rises above the summit crater of Semeru on August 17, 1985. Semeru has been in continuous activity since 1967, producing frequent small-to-moderate explosions that eject ash and volcanic bombs. More-infrequent, larger eruptions have produced pyroclastic flows and lahars that have reached the foot of the volcano.

Photo by Tom Casadevall, 1985 (U.S. Geological Survey).
Explosive eruption at the summit crater of Semeru on August 17, 1985. This activity is typical of Semeru, which has been in continuous eruptive activity since 1967, producing frequent small-to-moderate explosions that eject ash and volcanic bombs. More-infrequent, larger eruptions have produced pyroclastic flows and lahars that have reached the foot of the volcano.

Photo by Tom Casadevall, 1985 (U.S. Geological Survey).
The symmetrical Semeru volcano rises to 3676 m, the highest point in Java. This 1985 view from the SE shows Semeru rising dramatically above the coastal plain during one of its frequent small explosive eruptions. Larger eruptions occasionally produce pyroclastic flows and lahars that reach as far as the lower flanks of the volcano. Semeru (also known as Mahameru--"Great Mountain") has been in continuous activity since 1967.

Photo by Tom Casadevall, 1985 (U.S. Geological Survey).
Symmetrical Gunung Semeru volcano, the highest in Java, rises dramatically above cultivated land to its south. The volcano lies at the southern end of the Mount Bromo-Tengger-Gunung Semeru Reserve. The name Semeru means "One Mountain." Also known as Mahameru ("Great Mountain"), Semeru is named after the Indian subcontinent World Mountain--Meru. Legend states that all other mountains in Java fell away from Semeru on its mythological journey from the Himalayas.

Photo by Tom Casadevall, 1986 (U.S. Geological Survey).
Bromo volcano steams at the left in this view from the rim of Ngadisari caldera, the older of two Tengger calderas. The pyroclastic cones of Bromo and the conical, parasol-ribbed Batok in the lower center, are two of several post-caldera cones of Tengger caldera. The towering conical peak of Semeru, Java's highest volcano, appears in the background at the end of a long N-S trending volcanic massif.

Photo courtesy of Volcanological Survey of Indonesia.
Semeru, Java's highest volcano, is seen in eruption on the skyline at the southern end of a volcanic chain extending from Tengger caldera on the north. The ribbed post-caldera cone of Batok is the center foreground and the steaming cone of Bromo in the left foreground. This sunrise view from the rim of Tengger caldera is a popular tourist destination.

Photo by Lee Siebert, 1995 (Smithsonian Institution)
A vertical eruption column rises above the summit crater and a pyroclastic flow descends the southern flank of Semeru volcano in this view from the Gunung Sanur Volcano Observation Post of the Volcanological Survey of Indonesia. The symmetrical stratovolcano is one of the most active in Java and has been in continual eruption since 1967. Frequent small-to-moderate explosive eruptions are occasionally superceded by larger eruptions that produce pyroclastic flows and lahars that have reached the foot of the volcano.

Photo courtesy of Volcanological Survey of Indonesia, 1992.

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Carn S A, 1999. Application of synthetic aperture radar (SAR) imagery to volcano mapping in the humid tropics: a case study in East Java, Indonesia. Bull Volc, 61: 92-105.

Carn S A, Pyle D M, 2001. Petrology and geochemistry of the Lamongan volcanic field, east Java, Indonesia: primitive Sunda arc magmas in a extensional tectonic setting?. J Petr, 42: 1643-1683.

Mulyadi E, Zaennudin, Wahyudin D, Dana I N, 2000. Guide book for field excursion at Lamongan, Semeru, Bromo-Tengger volcanic complex, East Java, 13-17 July 2000. IAVCEI General Assembly, Bali 2000 Excursion Guide, 28 p.

Neumann van Padang M, 1951. Indonesia. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 1: 1-271.

Siswowidjoyo S, Sudarsono U, Wirakusumah A D, 1995. The threat of hazards in Semeru volcano, East Java, Indonesia. Eight Regional Conf GEOSEA '95, Manilla, Philippines, 14-18 Feb 1995, 17 p.

Suryo I, 1986. G Semeru. Bull Volc Surv Indonesia, 111: 1-52 (in Indonesian).

Thouret J-C, Lavigne F, Suwa H, Sukatja-Surono B, 2007. Volcanic hazards at Mount Semeru, East Java (Indonesia), with emphasis on lahars. Bull Volc, 70: 221-244.

van Bemmelen R W, 1937. The volcano-tectonic structure of the residency of Malang (eastern Java). Ing Ned-Indie, 4: 159-172.

Wahyudin D, 1990. Volcanology and petrology of Mt. Semeru volcanic complex, East Java - Indonesia. Unpublished undergraduate thesis, Victoria University of Wellington, 131 p.

Volcano Types

Stratovolcano
Pyroclastic cone(s)
Fissure vent(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
2,686
8,375
1,022,197
20,098,931

Affiliated Databases

Large Eruptions of Semeru Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.