Lewotobi

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  • Indonesia
  • Indonesia
  • Stratovolcano(es)
  • 2003 CE
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  • Primary Volcano Type
  • Last Known Eruption
  • 8.542°S
  • 122.775°E

  • 1703 m
    5586 ft

  • 264180
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Most Recent Weekly Report: 1 October-7 October 2014


Based on analysis of satellite images and wind data, the Darwin VAAC reported that on 6 October a narrow, low-level ash plume from Lewotobi rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 185 km WNW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


Most Recent Bulletin Report: April 2009 (BGVN 34:04)


Drops in steaming and seismicity during March 2009

Unrest caused authorities to elevate the alert level here to 2 in May 2008 (BGVN 34:01). No ash emissions were reported, as has been the case since 2003 (BGVN28:06, 28:10, 34:01).

On 23 March 2009, the Center for Volcanology and the Mitigation of Geologic Disaster (CVGHM) lowered the alert level on Lewotobi from 2 to 1 (on a scale of 1-4). This shift was based on visual observations and decreased seismicity during March. Rarely seen diffuse white plumes rose 25 m above the crater and drifted E. Visitors and residents continued to be advised not to approach the crater.

Over the period 1-23 March 2009 a cluster of shallow volcanic earthquakes occurred. Their initial numbers, 5-25 daily, soon declined to 1-5 occurrences per day. The total number of deep volcanic earthquakes did not change, averaging 1-3 daily. No tremor had been recorded since 1 February 2009 and at least as late as mid-2009.

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/); 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/); Agence France-Presse (URL: http://www.afp.com/); Jakarta Post (URL: http://www.thejakartapost.com/).

Index of Weekly Reports


2014: October
2012: March
2011: August | September
2009: March
2008: May
2003: June | July | August | October
2002: October

Weekly Reports


1 October-7 October 2014

Based on analysis of satellite images and wind data, the Darwin VAAC reported that on 6 October a narrow, low-level ash plume from Lewotobi rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 185 km WNW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


28 March-3 April 2012

CVGHM reported that seismicity at Lewotobi Lakilaki, one of two stratovolcanoes comprising Lewotobi, fluctuated but declined overall during 18 September 2011-25 March 2012. No significant changes were observed at the volcano. The Alert Level was lowered to 1 (on a scale of 1-4) on 29 March.

Observers of Lewotobi Perempuan, the second stratovolcano comprising Lewotobi, noted that during January-March diffuse white plumes rose 15 m above the crater and no significant changes had occurred. After 31 August 2011 through 25 March 2012 seismicity fluctuated but declined overall. On 29 March the Alert Level was lowered to 1.

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


21 September-27 September 2011

CVGHM raised the Alert Level for Lewotobi Lakilaki, one of two stratovolcanoes composing Lewotobi, to 2 (on a scale of 1-4) on 22 September due to increased seismicity since 17 September and visual observations. Although no significant changes in the volcano were observed, diffuse white plumes rose 15 m above the crater. Visitors and residents were prohibited from going within a 1-km radius of Lewotobi Lakilaki.

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


31 August-6 September 2011

CVGHM reported that during 26-31 August seismicity at Lewotobi increased. Plumes of "smoke" rose 15-50 m above the Lewotobi Perampuan crater rim; no other significant changes were visibly apparent. Based on the seismic data, the Alert Level was raised to 2 (on a scale of 1-4) on 31 August. Visitors and residents were advised not to approach the volcano within 1 km of the Lewotobi Perampuan crater.

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


18 March-24 March 2009

On 23 March, CVGHM lowered the Alert Level for Lewotobi from 2 to 1 (on a scale of 1-4) based on visual observations and decreased seismicity during March. Rarely seen diffuse white plumes rose 25 m above the crater and drifted E. Visitors and residents were advised not to approach the crater.

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


28 May-3 June 2008

On 29 May, CVGHM raised the Alert Level for Lewotobi to 2 (on a scale of 1-4) due to an increase in seismicity during 12-29 May. White plumes typically rose about 25 m above the crater and drifted E; visual observations indicated no changes.

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


29 October-4 November 2003

A decrease in volcanic activity at Lewotobi during 13-19 October led DVGHM to decrease the Alert Level from 2 to 1 (on a scale of 1-4). Only gas was emitted to low levels and no volcanic earthquakes were recorded.

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


27 August-2 September 2003

The Darwin VAAC reported that an eruption at Lewotobi on 1 September produced an ash plume to a height of ~2.5 km above the summit that drifted W. Volcanic material caused fires in forests within a 1 km radius of the crater and damaged crops on the volcano's flanks. VSI raised the Alert Level to 4, the highest level. According to news articles, hundreds of people from at least six villages fled their homes for the village of Konga to the E. By 2 September the Alert Level had been reduced to 3.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC); Agence France-Presse (AFP)


2 July-8 July 2003

Low-level ash emissions continued at Lewotobi during 2-29 June. During 2-8 June ash plumes reached ~300 m above the summit, and ash fell in the villages of Bawalatang, Duang, and Boru. Lewotobi remained at Alert Level 2 (on a scale of 1-4).

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


11 June-17 June 2003

On 30 May at 1650 an ash explosion at Lewotobi Lakilaki, a stratovolcano of Lewotobi, sent an ash column to a height of ~200 m above the summit. Ash fell at the observatory post about 5 km from the crater. As of 1 June, Lewotobi was at Alert Level 2 (on a scale of 1-4).

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


9 October-15 October 2002

On 12 October at 2330 there was an explosion at Lewotobi Lakilaki, a stratovolcano of Lewotobi, that was accompanied by a weak thundering sound. Ash fell as far as 5 km away and an ash column rose ~500 m above the volcano. According to VSI, eruptions at Lewotobi usually occur over an extended period of time, therefore they expect more explosions to take place in the next couple of weeks to months. On 16 October, Lewotobi was at Alert Level 4 (the highest level).

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); 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.

04/1991 (BGVN 16:04) Brief increase in seismicity

05/1991 (BGVN 16:05) Ash emission follows increased seismicity

06/1991 (BGVN 16:06) Strombolian activity; ash to 300 m height; several hundred explosion earthquakes weekly

07/1991 (BGVN 16:07) Strombolian activity

11/1991 (BGVN 16:11) Continued gas emission

05/1999 (BGVN 24:05) March-May ash eruptions

07/1999 (BGVN 24:07) 1 July explosion ignites fires and up to 1 mm of ash falls on local villages

11/2002 (BGVN 27:11) Explosion on 12 October 2002, the first reported activity since July 1999

06/2003 (BGVN 28:06) Minor explosion and ashfall on 30 May

10/2003 (BGVN 28:10) Explosions and ashfall during June-July; seismicity stops in early September

01/2009 (BGVN 34:01) Increase in seismicity during May 2008; more details on 2003 eruption

04/2009 (BGVN 34:04) Drops in steaming and seismicity during March 2009




Bulletin Reports

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


04/1991 (BGVN 16:04) Brief increase in seismicity

A sudden increase in seismicity, from 7 to 60 earthquakes/day, was recorded at the end of March. Activity peaked on 26 March, then gradually decreased. No changes in surface activity were observed.

Information Contacts: W. Modjo, VSI.

05/1991 (BGVN 16:05) Ash emission follows increased seismicity

Ash was erupted to 800 m height, and deposited to 7 km NE and 4 km NW, on 11-13 May. Gas emission continued through the end of May, with 84 emission events recorded during the last week. Twelve shallow and seven deep volcanic earthquakes were also recorded during the last week in May.

Information Contacts: W. Modjo, VSI.

06/1991 (BGVN 16:06) Strombolian activity; ash to 300 m height; several hundred explosion earthquakes weekly

Explosions at the summit crater on 28 May at 1615, 1840, and 1911 produced ash clouds to 300 m, accompanied by thunder-like sounds heard 4 km SW of the crater (at Pos Observatory). Since then, activity has been dominated by gas emissions and explosion earthquakes (figure 1). Explosions emitted ash (12-19 times/week) to 100-300 m high. On 8 and 13 June, lapilli and bombs ejected by Strombolian activity covered the area surrounding the crater. Glow and lava fountaining then steadily diminished through the end of June. Explosion earthquakes were recorded 200-405 times/week, compared to 0-4 deep and shallow volcanic earthquakes, and 5-7 tectonic earthquakes/week. No tremor episodes were recorded.

Figure 1. Daily number of earthquakes and explosion events at Lewotobi Lakilaki, May 1991. Arrows represent explosions. Courtesy of VSI.

Information Contacts: W. Modjo, VSI.

07/1991 (BGVN 16:07) Strombolian activity

Press releases reported increased activity, with small eruptions occurring around 19 July. One eruption reportedly ejected incandescent material 100 m high, dropping hot ash (smelling of sulfur) onto nearby areas and causing residents to flee. At 1645 on 29 July, a 300-m-high ash cloud extending ~35 km W was reported by pilots on Qantas flight A61. By the week of 14-19 August the volcano was no longer exploding, and gas emissions, 50-100 m high, appeared to be decreasing.

Information Contacts: W. Modjo, VSI; ICAO; UPI.

11/1991 (BGVN 16:11) Continued gas emission

Degassing has continued since October, sometimes punctuated by ash ejection reaching 50-150 m above the crater. The number of degassing earthquakes dropped slightly from 246 during the first week of December to 233 in the second week. One B-type volcanic earthquake was recorded during the two-week period.

Information Contacts: VSI.

05/1999 (BGVN 24:05) March-May ash eruptions

The current phase of activity at Lewotobi Lakilaki began at 0547 on 21 March, when observers noted a vigorous steam plume rising 250 m above the summit. This was noteworthy because when the volcano is in a non-active phase its steam plume rises no higher than ~25 m. On 30 March a rumbling noise was heard and the volcano's status was raised to Level II, or "Alert." The following day observers twice noted ash plumes ~250 m high accompanied by a rumbling noise. On 1 April observers saw such plumes at three different times.

From 27 April to 3 May the ash eruption continued. The observed ash was whitish-gray, of weak to moderate pressure, and extending 300 m above the summit. Eruption events were sometimes accompanied by detonations. On 29 April, glowing material was ejected 50-75 m above the crater and it fell over an area with 50 m radius. Thin ash fell over the Boru area the following day at 1600. The seismic record totals for the week showed four volcanic type-B, nine tectonic, four eruption, and nine emission events.

Ash eruptions reached heights of 500 m during 4-10 May and were sometimes accompanied by strong detonations. On 7 and 9 May glowing materials were again ejected to 50-75 m heights, falling within a 50 m radius. On 7 May ash fell around the areas of Boru, Riang Boru, Hokeng, and Wolorona. Deposits were ~1 mm thick. Seismic events for the week decreased, with three eruptive and five emission events. From 11 through 17 May ash eruptions continued to reach heights of 500 m and were sometimes accompanied by strong detonations. During the week of 18-24 May emission heights decreased to 300 m and blast sounds became less frequent. Thin ash fell during 19 May on the Boru and Riagulu regions.

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

07/1999 (BGVN 24:07) 1 July explosion ignites fires and up to 1 mm of ash falls on local villages

Lewotobi Laki-Laki erupted at 1000 on 1 July. A strong blast accompanied the eruption. Glowing material fell in a 500 m radius to the N and S, igniting forest fires that extended 2.5 km N of the crater and 500 m S, to the ridge dividing Lewotobi Laki-Laki from Lewotobi Perempuan. Ash emissions reached 1,000 m above the summit and were distributed to the W, SW, and S. The emissions then drifted to the NW, W, SW, and S in an 8-km radius. The settlements of Boru, Bawalatang, and Watukubu reported ash deposits in the range 0.5-1 mm thick.

"White, thin-to-thick ash emissions" have continued since the initial eruption, rising ~100 m above the summit. Authorities raised the volcano status to "Level III" (prepare to evacuate) on 2 July. The seismic record for the week 29 June to 5 July reported 266 type-A, 70 type-B, two tectonic, and 31 explosive events.

Information Contacts: R. Sukhyar and Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).

11/2002 (BGVN 27:11) Explosion on 12 October 2002, the first reported activity since July 1999

On 12 October 2002 at 2330, an explosion at Lewotobi Lakilaki (a twin stratovolcano of Lewotobi Perempuan) was accompanied by a weak thundering sound that was heard at Hokeng village, 5 km from the summit. An ash column rose ~500 m above the volcano and drifted NW. Ash fell as far as 5 km away, accumulating to thicknesses of less than 0.5 mm. No seismic data were available. Following the eruption, the Alert Level was raised to 2 (on a scale of 1-4). According to VSI, eruptions at Lewotobi usually occur over an extended time, therefore more explosions were expected in the following weeks to months. VSI reported no increase in volcanism in the weeks following the 12 October eruption. Through at least 24 November, a thin white low-pressure ash plume was frequently visible rising 150-250 m above the summit. Lewotobi remained at Alert Level 2.

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/).

06/2003 (BGVN 28:06) Minor explosion and ashfall on 30 May

An explosion on 12 October 2002 at Lewotobi Lakilaki, one of the twin stratovolcanoes that comprise Lewotobi, produced an ash column that rose ~500 m above the volcano (BGVN 27:11). Through at least 24 November, a "thin white low-pressure ash plume" rose 150-250 m above the summit.

No further reports were issued until May 2003, when the Volcanological Survey of Indonesia reported an explosion at 1650 on 30 May 2003. The resulting ash column reached 200 m above the summit and caused ashfall at the observatory, ~5 km from the crater. Visual and seismic data showed no significant increases during the week prior to the explosion (table 1). On 1 June, two explosion earthquakes and two tremor earthquakes were recorded. The hazard status was set at Alert Level 2 (on a scale of 1-4).

Table 1. Seismicity and height of the gas plume at Lewotobi during 20 May-15 June 2003. Courtesy VSI.

    Date (2003)   Volcanic   Tectonic      Ash      Tremor   Plume
                                        Emissions            Height(s)

    20 May            2          1          --        --       25 m
    21 May            0          0          --        --       --
    22 May            4          1          --        --       25 m
    23 May            9          5          --        --       25 m
    24 May            6          3          --        --       25 m
    25 May            5          1          --        --       25 m
    26 May            0          0          --        --       25 m
    27 May            2          6          --        --       25 m
    28 May            0          2          --        --       --
    29 May            2          0          --        --       --
    30 May            6          3          --        --      200 m
    31 May            6          0          --        --       --
    01 Jun            3          1          --        --       --
    02-08 Jun        13         12          29        20      300 m
    09-15 Jun        24          9          40        33       75 m

Activity during the week of 2-8 June 2003 was marked by explosions and ash emissions. Ash plumes reached a maximum height of 300 m above the summit. Seven explosions were recorded accompanied by a blasting sound on 3, 5, and 6 June. Ash fell at Bawalatang, Duang, and Boru villages. Shallow volcanic earthquakes were recorded, but were fewer in number compared to the previous week; there was no record of deep volcanic earthquakes, although tectonic earthquakes were recorded.

During the week of 9-15 June, activity was marked by ash emissions, with an ash plume reaching a maximum height of 75 m above the summit. Tremor events were also observed, with the tremor showing an amplitude of 0.5-7 mm. There were no deep volcanic earthquakes recorded, although the numbers of shallow volcanic earthquakes, tremor and ash emissions increased.

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/).

10/2003 (BGVN 28:10) Explosions and ashfall during June-July; seismicity stops in early September

Explosive ash eruptions from the summit crater of Lewotobi sent dark gray plumes 300-350 m high between 2 June and 13 July. Detonation sounds accompanied explosions on 3, 5, and 6 June. Ash fell in the villages of Bawalatang, Duang, and Boru in early June, and was reported at the volcano observatory post in early July. Ash explosions continued during 14-20 July with plumes rising 150 m above the summit. Poor weather conditions prevented observations in late July, although seismic records indicated continued activity; no reports were available for August. In early September an ash plume was reported to rise 25 m above the crater.

Seismicity during June and July was dominated by emissions events, but included tremor, explosion, and shallow volcanic earthquakes (table 2). Early September seismicity consisted of a high number of shallow volcanic events and some deep volcanic earthquakes, but all seismicity ceased after 3 September. Only four tectonic earthquakes were detected after this date, during 6-19 October. The 29 September-5 October report noted an ash plume rising to 25 m above the crater, but over the next two weeks the 25-m-high plume was described as gas emissions. The hazard status was downgraded to Alert Level 1 (on a scale of 1-4) the week of 13-19 October.

Table 2. Seismicity at Lewotobi, 2 June-19 October 2003. Note that no seismicity was recorded after 3 September 2003. Courtesy of VSI.

    Date (2003)        Deep     Shallow    Explosion   Emission   Tremor   Tectonic
                     Volcanic   Volcanic

    02 Jun-08 Jun        0         13          7          29        20        12
    09 Jun-15 Jun        0         24         --          40        33         9
    30 Jun-06 Jul        0          8         14          26        11         3
    07 Jul-13 Jul        0         16         10          52         4         1
    14 Jul-20 Jul        4         17         19          24        10         4
    21 Jul-27 Jul        1         10          5          25         5         4
    28 Jul-03 Aug        0          9          8          20         6         3
    01 Sep-03 Sep*      27        257          0           0         0         5

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/).

01/2009 (BGVN 34:01) Increase in seismicity during May 2008; more details on 2003 eruption

On 29 May 2008, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) raised the Alert Level for the Flores Island volcano Lewotobi to 2 (on a scale of 1-4) due to an increase in seismicity during 12-29 May. White plumes typically rose about 25 m above the crater and drifted E; visual observations indicated no changes.

Explosive ash eruptions and high levels of seismicity occurred during May-September 2003 (BGVN28:06 and 28:10). Seismicity declined dramatically after an eruption on 31 August, and all volcanic earthquakes ceased after 3 September. The absence of reports during October 2003 until mid-May 2008 suggests Lewotobi apparently entered a protracted period of quiescence until May 2008. MODVOLC thermal surveillance of Lewotobi subsequent to the activity of October 2003 has not revealed any significant thermal activity to February 2009.

Additional details of 2003 eruption.According to an Agence France-Presse (AFP) news report, an eruption on 31 August 2003 took place at 1935. The article noted that hundreds of people from at least six villages fled E from their homes to the village of Konga. AFP said that volcanic material caused fires in forests within a 1-km radius of the crater and damaged crops on the flanks. On 1 September CVGHM reported to the Darwin Volcanic Ash Advisory Center (VAAC) that an ash plume rose ~2.5 km above the crater and drifted W, but the plume was not detected in imagery.

Following that 2003 eruption, according to the daily Jakarta Post, at least 565 villagers living on the slopes of Lewotobi were affected by sulfur and ash emissions. The residents experienced respiratory problems and skin afflictions. A 2008 Jakarta Post article indicated that an estimated 10,000 people live on the slopes of Lewotobi, most of them farming the fertile volcanic soil in the area.

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/); 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/); Agence France-Presse (URL: http://www.afp.com/); Jakarta Post (URL: http://www.thejakartapost.com/).

04/2009 (BGVN 34:04) Drops in steaming and seismicity during March 2009

Unrest caused authorities to elevate the alert level here to 2 in May 2008 (BGVN 34:01). No ash emissions were reported, as has been the case since 2003 (BGVN28:06, 28:10, 34:01).

On 23 March 2009, the Center for Volcanology and the Mitigation of Geologic Disaster (CVGHM) lowered the alert level on Lewotobi from 2 to 1 (on a scale of 1-4). This shift was based on visual observations and decreased seismicity during March. Rarely seen diffuse white plumes rose 25 m above the crater and drifted E. Visitors and residents continued to be advised not to approach the crater.

Over the period 1-23 March 2009 a cluster of shallow volcanic earthquakes occurred. Their initial numbers, 5-25 daily, soon declined to 1-5 occurrences per day. The total number of deep volcanic earthquakes did not change, averaging 1-3 daily. No tremor had been recorded since 1 February 2009 and at least as late as mid-2009.

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/); 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/); Agence France-Presse (URL: http://www.afp.com/); Jakarta Post (URL: http://www.thejakartapost.com/).

The Lewotobi "husband and wife" twin volcano (also known as Lewetobi) in eastern Flores Island is composed of the Lewotobi Lakilaki and Lewotobi Perempuan stratovolcanoes. Their summits are less than 2 km apart along a NW-SE line. The conical 1584-m-high Lewotobi Lakilaki has been frequently active during the 19th and 20th centuries, while the taller and broader 1703-m-high Lewotobi Perempuan has erupted only twice in historical time. Small lava domes have grown during the 20th century in the crescentic summit craters of both volcanoes, which are open to the north. A prominent flank cone, Iliwokar, occurs on the east flank of Lewotobi Perampuan.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2003 May 30 2003 Sep 1 (in or after) Confirmed 2 Historical Observations Lewotobi Lakilaki
2002 Oct 12 2002 Oct 12 (?) Confirmed 1 Historical Observations Lewotobi Lakilaki
1999 Mar 31 1999 Jul 1 (?) Confirmed 2 Historical Observations Lewotobi Lakilaki
1991 May 11 1992 Dec 31 (in or after) Confirmed 1 Historical Observations Lewotobi Lakilaki
1990 Jan 28 1990 Jun Confirmed 1 Historical Observations Lewotabi Lakilaki
1971 Jan Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1970 Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1968 Nov 28 1969 Feb 2 Confirmed 2 Historical Observations Lewotobi Lakilaki
1939 Dec 17 1940 Apr 21 Confirmed 2 Historical Observations Lewotobi Lakilaki
1935 Dec 1935 Dec 25 (in or after) Confirmed 2 Historical Observations Lewetobi Perempuan
1932 May 23 1933 Dec 26 ± 5 days Confirmed 3 Historical Observations Lewotobi Lakilaki
1921 Jan 1 1921 Dec 20 Confirmed 2 Historical Observations Lewotobi Perempuan
1914 Jun 29 Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1909 Jan 8 1910 May 26 Confirmed 2 Historical Observations Lewotobi Lakilaki
1907 Sep 28 1907 Oct 30 Confirmed 3 Historical Observations Lewotobi Lakilaki
1889 Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1869 Jul 7 1869 Jul 27 Confirmed 2 Historical Observations Lewotobi Lakilaki
1868 Dec 15 Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1868 Jul 13 (in or before) Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1865 May 4 Unknown Confirmed 2 Historical Observations Lewotobi Lakilaki
1861 May 4 1861 May 18 Confirmed 2 Historical Observations Lewotobi Lakilaki
[ 1859 Jul ] [ Unknown ] Uncertain     Lewotobi Lakilaki
1675 ± 25 years Unknown Confirmed 3 Historical Observations Lewotobi Lakilaki

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

Lobetobi | Lewetobi | Lowetobi | Lebetobi | Nobo, Mount

Cones

Feature Name Feature Type Elevation Latitude Longitude
Iliwokar Cone 780 m
Lewetobi Perempuan
    Lewetobi Perampuan
Stratovolcano 1703 m 8° 34' 30" S 122° 47' 0" E
Lewotobi Lakilaki
    Nobo, Mount
Stratovolcano 1584 m 8° 32' 0" S 122° 46' 30" E
The twin "Husband and Wife" volcanoes of Lewotobi Lakilaki (left) and Lewotobi Perempuan (right) rise above a village on their western flanks. Both the conical Lakilaki and the broad Perempuan volcanoes have erupted during historical time, but the sharper-peaked Lakilaki has been the more active.

Photo courtesy of Volcanological Survey of Indonesia, 1990.
The twin volcanoes of Gunung Lewotobi present dramatically differing profiles when seen from the SW. The summit of sharp-peaked Lewotobi Lakilaki (left) lies only 2 km NW of the broader summit of Lewotobi Perempuan. Both volcanoes have erupted during historical time.

Photo published in Kemnerling 1929, "Vulkanen van Flores" (courtesy of Volcanological Survey of Indonesia).
The NE flanks of Gunung Lewotobi volcano rise above the village of Nobo. Flat-topped Lewotobi Perempuan (left) is located SW of its twin volcano, Lewotobi Lakilaki (right). Both of these volcanoes, known as the "Husband and Wife" volcanoes, have erupted during historical time, although Lakilaki, the "Husband," has erupted much more frequently.

Photo published in Kemnerling 1929, "Vulkanen van Flores" (courtesy of Volcanological Survey of Indonesia).
The first historical eruption of Lewotobi Perempuan took place in 1921, when explosive eruptions and lava dome growth were reported in January, May, and December. A steam column rises above the dome in this 1920's view from the NE. The 35-m-high lava dome was emplaced on the floor of crater B, the innermost of two craters at the summit of Lewotobi Perempuan.

Photo published in Kemnerling 1929, "Vulkanen van Flores" (courtesy of Volcanological Survey of Indonesia).
The new lava dome emplaced in 1921 on the floor of the summit crater of Lewotobi Perempuan is seen from the NW crater rim in 1925. The 35-m-high dome was formed during the first of only two historical eruptions from Lewotobi Perempuan. In contrast, its twin volcano, Lewotobi Lakilaki, has erupted frequently since the 19th century.

Photo published in Kemnerling 1929, "Vulkanen van Flores" (courtesy of Volcanological Survey of Indonesia).
Steam rises above a lava dome emplaced in the summit crater of Lewotobi Perempuan volcano in 1921. The 90-130 m wide, 35-m-high lava dome is seen here from the NW crater rim.

Photo published in Kemnerling 1929, "Vulkanen van Flores" (courtesy of Volcanological Survey of Indonesia).
The twin "Husband and Wife" volcanoes of Lewotobi Lakilaki (left) and Lewotobi Perempuan (right) rise above forests on their western flanks. The twin volcanoes were constructed along a NW-SE-trending line. Both the conical Lakilaki and the broad Perempuan volcanoes have erupted during historical time, but the sharper-peaked and sparsely vegetated Lakilaki has been the more active.

Photo by Joël Boyer, 2004 (L.A.V.E.)

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.

Kemmerling G L L, 1929. Vulkanen van Flores. Vulk Seism Meded Dienst Mijnw Ned-Indie, 10: 1-138.

Kusumadinata K, 1979. Data Dasar Gunungapi Indonesia. Bandung: Volc Surv Indonesia, 820 p.

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

Stolz A J, Varne R, Davies, G R, Wheller G E, Foden J D, 1990. Magma source components in an arc-continent collision zone: the Flores-Lembata sector, Sunda arc, Indonesia. Contr Mineral Petr, 105: 585-601.

Wheller G E, Varne R, Foden J D, Abbott M J, 1987. Geochemistry of Quaternary volcanism in the Sunda-Banda arc, Indonesia, and three-component genesis of island-arc basaltic magmas. J Volc Geotherm Res, 32: 137-160.

Volcano Types

Stratovolcano(es)
Stratovolcano(twin)
Lava dome(s)

Tectonic Setting

Subduction zone
Crustal thickness unknown

Rock Types

Major
Andesite / Basaltic Andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
18,686
59,084
284,976
906,184

Affiliated Databases

Large Eruptions of Lewotobi 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.