Bulletin of the Global Volcanism Network

All reports of volcanic activity published by the Smithsonian since 1968 are available through a monthly table of contents or by searching for a specific volcano. Until 1975, reports were issued for individual volcanoes as information became available; these have been organized by month for convenience. Later publications were done in a monthly newsletter format. Links go to the profile page for each volcano with the Bulletin tab open.

Information contained in these reports is preliminary at time of publication and subject to change.

 Bulletin of the Global Volcanism Network - Volume 39, Number 10 (October 2014)


Managing Editor: Richard Wunderman

Bardarbunga (Iceland)

Substantial dike eruption~45 km NE at Holuhraun begins 29 August 2014

Klyuchevskoy (Russia)

Two eruptive pulses: 15 August-20 December 2013 and 1 January-24 March 2015

Merapi (Indonesia)

During June 2011 to December 2014, several eruptions and elevated seismicity

Sinabung (Indonesia)

May-October 2014: Frequent eruptions, pyroclastic flows, and advancing lava-flow lobe


Bardarbunga

Iceland

64.63°N, 17.53°W; summit elev. 2009 m

All times are local


Substantial dike eruption~45 km NE at Holuhraun begins 29 August 2014

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This is our first Bulletin report on Bardarbunga, a subglacial caldera found within the Barbarbunga volcanic system. This report is divided into two major sections, the first discussing activity between 1986 and 2008 and the second looking at more recent activity from 2014-early 2015.

As background, Bardarbunga, the second highest volcano of Iceland, is one of approximately 30 known Holocene volcanoes or volcano systems in the country. It lies beneath the NW part of the Vatnajokull ice cap. Carrivick and Gertisser (2014) described the volcano as a caldera 700 m deep with a diameter of 11 km, covered by glacial ice ~850 m thick.

1986-2008 activity. In 2010, the Icelandic Meteorological Office (IMO) presented a list of Icelandic volcanic eruptions from 1902-2010 on their website. That list lacks any eruption at the Bardarbunga caldera. Seibert and others (2010) stated that between 1986 and 2008, there were several uncertain cases of eruptions or unrest in the area of Loki-Fögrufjöll (S-SW of Bardarbunga caldera), which they consider a part of the larger Bardarbunga volcanic system (green in figure 1). The eruptive characteristics of these events included regional fissure and subglacial events associated with jökulhlaups (glacier bursts).

Figure 1. Map of Iceland that highlights the Bardarbunga volcanic system (shaded in green), which is 190 km long (NE-SW) and up to 25 km wide (NW-SE). The main Bardarbunga volcano, a subglacial caldera, is represented by the letter ‘B’ on the map. This map, showing all of Iceland was part of a more detailed map of the Bardarbunga volcanic system. Iceland’s capital, Reykjavik, and other towns are also highlighted on the map. Taken from Larsen and others (2014).

 

The associated jökulhlaups from 1986-2008 originated from the East and West Loki cauldrons found along the Loki Ridge of the Loki-Fögrufjöll system (figure 2). The cauldrons are located ~15 km SW of the center of the Bardarbunga caldera. Other terms for the Loki cauldrons include the East and West Skaftárketill cauldrons; the Eastern and Western Skaftá cauldrons; and the Eastern and Western cauldrons.

Figure 2. Two maps showing the location of East and West Loki cauldrons on the Vatnajokull glacier surface. The Loki cauldrons are found along the Loki Ridge of the Loki-Fögrufjöll system, located SW of Bardarbunga volcano and are within the larger Bardarbunga volcanic system. (Top) The Loki cauldrons are labeled as the Eastern and Western Skaftá cauldrons. (Bottom) The cauldrons are labelled the Eastern and Western cauldrons and the Skatfá river is highlighted. Both maps highlight the inferred subglacial water route (black and green lines) of melt water that is eventually discharged during a jökulhlaup. The jökulhlaups that originate from the Loki cauldrons empty into the Skatfá river. Top map after being taken from Marteinsson and others (2013) was slightly edited and the bottom map was taken from Einarsson (2009).

 

The Loki cauldrons are depressions formed in the Vatnajokull glacier surface by two underlying, subglacial geothermal areas (Einarsson, 2009). The geothermal areas melt the glacier’s base and melt water collects forming subglacial lakes. As the lakes grow, the ice above them flattens. Eventually, the melt water escapes from the subglacial lakes in a jökulhlaup. The water of the jökulhlaup then travels ~40 km subglacially to flood the Skatfá river (Einarsson, 2009). Once the subglacial lake has emptied, the overlying ice collapses and the cauldrons can be seen again in the glacier surface (Einarsson, 2009).

Table 1 below presents the dates of uncertain cases of eruption within the Bardarbunga volcanic system. The source of the jökulhlaups associated with these uncertain eruptions consistently originated from the East or West Loki cauldron or both.

Table 1. Table condensing Bardarbunga’s uncertain cases of eruptive history during 1986-2008. The uncertain cases all reside in the area of Loki-Fögrufjöll. The table also show the source of the jökulhlaup associated with each of the cases. None of these uncertain cases occurred at the Bardarbunga caldera. Data in this table summarizes written communication with Páll Einarsson in 2008.

Year/Month Jökulhlaup source
1986/11 East Loki
1991/08 East Loki
1995/07 East Loki
1996/08 West Loki
1997/08 East Loki
2000/08 East and West Loki
2002/07 West Loki
2002/09 East Loki
2005/07-08 West Loki
2006/04 East Loki
2008/08 West Loki

 

Two examples of uncertain eruptions at the East Loki cauldron follow. They occurred in November 1986 and August 1991. For the 1986 case, Björnsson and Einarsson (1990) stated, “There is a seismic indication that a small eruption occurred in 1986 during a Skaftá jökulhlaup from beneath the easternmost ice cauldron [figure 2]. The flood in Skaftá began on November 29, and on November 30 and the following day short bursts of continuous tremor were recorded on seismographs around Vatnajokull. . ..It is likely that the pressure release associated with the jökulhlaup triggered a short eruption that did not reach the surface of the glacier.”

For the 1991 case, Björnsson and Einarsson (1990) reported that “Bursts of tremor were recorded on seismographs near Vatnajokull on Aug. 12, 1991, during a jökulhlaup in Skaftá. The course of events is similar to that of Nov. 30, 1986, and suggests that a small and short-lived eruption may have occurred beneath the Eastern Loki cauldron.”

Based on the communication between Einarsson and GVP, the other cases in table 1 followed a similar pattern. For each of those events, the occurrence of a jökulhlaup was followed by either an eruption tremor or bursts of eruption tremor, which suggested the possibility of a small, subglacial eruption at East or West Loki.

Confirmed 1996 eruptions. There are two confirmed eruptions at Bardarbunga, both within a few weeks of each other in 1996 (1 and 2 below).

(1) Einarsson and others (1997) discuss the complex interplay of events that occurred during 29 September through 7 November 1996, which involved seismicity, dikes, jökulhlaups, and various eruptions at Bardarbunga, Grímsvötn and Gjálp (fissure between the two calderas). Einarsson and others (1997) start with this introduction: “A volcanic eruption beneath the Vatnajokull ice cap in central Iceland . . . began on September 30, 1996, along a 7-km-long fissure between the volcanoes Bardarbunga and Grímsvötn. The eruption continued for 13 days . . ..”

They further note “. . . a minor subglacial eruption occurred on the southeast rim of the Bardarbunga caldera, 6-7 km to the north. Two small depressions formed in the ice surface there.” Regarding this, Páll Einarsson added this comment in a 2015 email: “The small subglacial eruptions at the Bárðarbunga caldera rim, mentioned in our paper, are a separate event [from the one a few weeks later mentioned in (2) below]. They are evidenced by sinkholes in the glacier that were discovered late and the timing of these events is not known. Most likely the sinkholes were initiated during the Gjálp eruption, i.e. between September 30 and October 13.”

(2) According to the Institute of Earth Sciences of the University of Iceland (IES, posting date uncertain), a small eruption took place at Bardarbunga in 1996. They wrote the following: “A small eruption started in Bardarbunga around 1300 hrs on November 6th. The eruption lasted for about 20 to 30 min. According to seismograms at the Meteorological office, the eruption was initiated by some intrusive activity. The intrusive activity is based on recorded eruption tremor picked up [by] the seismometers. Eruption column reached about 4 km in to the air. Relation between pressure decrease due to the flooding [has] been suggested as the main cause of the eruption.” This eruption came a day after a jökulhlaup was released from the Grímsvötn caldera (BGVN 21:09 and 23:11, and IES (posting date uncertain). We have not found a clear description of where in the caldera the eruption took place on 6 November 1996.

In regards to the confirmed eruption of 6 November, Einarsson’s email made these remarks: “Keep in mind that Bárðarbunga is very remote and observations of the activity are difficult and very dependent on weather conditions. The webpage of our institute describes a small explosive event that happened on Nov. 6 at the end of the large jökulhlaup, when the meltwater from the large Gjálp eruption was flushed down to the coast. Most of us think now that this was a phreatic reaction of the still hot edifice to the sudden pressure release when the caldera lake of Grímsvötn was emptied, i.e. not due to a fresh injection of magma. But observations were scarce and there may be other opinions on this.”

2014-early 2015 activity. This section of the Bulletin report primarily summarizes events from 16 August 2014, when seismic activity began, into mid-January 2015. The eruption was still ongoing at that time.

Bardarbunga is monitored by a seismic network, an extensive GPS network, and various sensors such as webcams and infrared cameras. Monitoring and analyses at Bardarbunga is conducted by a group of collaborators that include the IMO, the Institute of Earth Sciences (IES) at the University of Iceland, and the National Commissioner of Police, and the Department of Civil Protection and Emergency Management.

Gudmundsson and others (2014) and IMO describe dike emplacement (without apparent breaching the ground surface) associated with a seismic swarm that began at the caldera and migrated tens of kilometers with branches to the N and NE during 16-31 August 2014. On 29 August 2014, two days before the swarm ended, an eruption was first documented at the surface at a flank vent devoid of ice cover ~45 km NE of the caldera.

Figures 3 and 4 help explain the location of volcanoes in Iceland and Bardarbunga lava that progressed northward as a dike and ultimately erupted in the Holuhraun vent.

 

Figure 3. IMO map of Iceland showing key Holocene volcano locations. Bardarbunga (yellow triangle) is located on the NW part of the 14,000 km2 Vatnajokull ice cap (continental glacier). Although seismicity and dike injection began at Bardarbunga, intrusive processes seemingly prevailed until dikes had propagated to Holuhraun (tip of arrow designated with “H”, location approximate). Holuhraun sits ~45 km NE of the caldera. Courtesy of Iceland Met Office.

 

Figure 4. A map reflecting Bardarbunga’s lava that erupted in the Holuhraun vent area between 29 August 2014 and about 15 January 2015 (shaded lens-shaped zone between the glacier and Askja volcano). The map shows the N margin of the Vatnajokull ice cap but Bardarbunga caldera lies 17 km off the map to lower left. The site of the eruptive fissure is in the vicinity of the orange bull’s eye. Dyngjujokull glacier is an outlet glacier that forms a N-trending lobe streaming N and outward from the much larger Vatnajokull glacier. Note the E end of the new flow field following the drainage system (the Jökulsá á Fjöllum river) Image published online by the Icelandic Met Office (IMO) on 15 January 2015 (based, in part, on a NASA Landsat 8 image).

 

The NE-trending dike reached an area outboard of the Vatnajokull ice cap at the Holuhraun volcanic field (figure 4), where the first clear eruption began on 29 August 2014. The fissure vent area was 4.5 km from the ice margin of the outlet glacier Dyngjujökull. The venting took place along an old fissure, and came out along an N-trending zone 600 m long. According to Gudmundsson and others (2014), that eruption was moderate and effusive.

Holuhraun is sometimes discussed in the context of Askja volcano (figure 4), which lies just to the N. Holuhraun is sometimes considered as peripheral vent system for Askja (Ialongo and others, 2015).

Figure 5 indicates the location of earthquakes during the first 16 days of dike emplacement (where days 1-16 correspond to 16-31 August 2014). Gudmundsson and others (2014) comment that “During this time, the dike generated some 17,000 earthquakes, more than produced in Iceland as a whole over a normal year.” The venting to the surface at Holuhraun took place on 29 August 2014 and became strong by 31 August. In the early hours of the 29 August, the onset consisted of a minor, four-hour long, fissure eruption. The pattern on figure 5, depicting a 45-km-long dike injection along the rift system passing through Bardarbunga, testifies to the importance and utility of the seismograph in monitoring shallow magmatism leading to eruption.

Figure 5. For the Bardarbunga eruption, earthquake locations during the first 16 days of the dike emplacement (16-31 August 2014). The word ‘Dike’ is located approximately where the fissure eruptions have taken place (at a volcanic field called Holuhraun). The white area is the Vatnajokull ice cap (including the associated Dyngjujokull outlet glacier; figure 4). Earthquake magnitudes are indicated in the lower right portion of the map. Taken from Gudmundsson and others (2014), based on preliminary data from IMO.

 

According to IMO, seismic activity associated with Bardarbunga had gradually increased during the last seven years, although it temporarily diminished during the Grimsvotn eruption in May 2011. Vatnajokull GPS stations showed both upward and outward movements since early June 2014, and on 16 August 2014, the number of earthquakes significantly increased, with more than 300 earthquakes detected under the NW part of Vatnajokull ice cap (figure 5). As a result, the Aviation Color Code was increased to Yellow, the third level from the highest on a five color scale (Gray, Green, Yellow, Orange, and Red). On 18 August, IMO reported one earthquake swarm to the E and another swarm to the N of Bardarbunga. An M 4 earthquake occurred, the strongest in the region since 1996. By 18 August, 2,600 earthquakes had been detected at the volcano; earthquake locations from the E and N swarms had been migrating NE. In the evening of 18 August, earthquakes diminished in the N swarm. That same day the Aviation Color Code was raised to Orange.

According to IMO, GPS and seismic data during 20-26 August suggested that a NE-trending intrusive dike had increased from 25 to 40 km in length. During 22-26 August, several earthquakes in the 4.7-5.7 magnitude range had been detected at or near the volcano. These values were among the largest detected in the first few weeks of the swarm (Gudmundsson and others, 2014). The Aviation Color Code, chiefly Orange during this reporting interval, rose to the highest level, Red, several times during late August and September.

On 23 August seismic tremor indicated what IMO initially suggested was a small lava eruption at beneath the Dyngjujokull glacier (which is 150-400 m thick in this region). An overflight the next day found no evidence for an eruption.

On 27 August an overflight showed a 4- to 6-km-long row of cauldrons 10-15 m in diameter S of Bardarbunga.

Beginning on 31 August, lava erupted along a 1.5 km long fissure. During 1-2 September a white steam-and-gas plume rose to an altitude of 4.5 km and drifted 60 km NNE and ENE. Lava flowed N and lava fountains rose tens of meters. The number of earthquakes decreased from 500 earthquakes on 1 September to 300 earthquakes on 2 September. During the middle of September, seismicity persisted mainly around the caldera and the Dyngjujokull glacier.

On 2 September the lava had covered 4.2 km2 and was 4.5 km from the glacier’s edge. By 3 September, the lava flow advanced ENE and covered 7.2 km2. The following day, the lava flow had an aerial extent of 10.8 km2. During 3-9 September, IMO observers noted ongoing lava effusion, high gas emissions, and elevated seismicity from the Holuhraun lava field. Ash production was almost negligible.

On 5 September, two new eruptive fissures were observed S of the main eruption site. These sites were less effusive and were located ~2 km from the edge of Dyngjujokull glacier (see this small shaded area in figure 2). The eruption also continued from the original fissure and generated a ~460 m high steam plume. Eventually, a row of craters formed along the eruptive fissure, the largest one was named Baugur crater.

The fissure eruption continued during 6-7 September, and the lava effusion rate was 100-200 m3/sec on 7 September (figures 6 and 7). Activity from the S fissures was less than that of the N fissure, which had been active since the beginning of the eruption. The advancing lava flow reached the W main branch of the Jökulsá á Fjöllum river (figure 4), which is fed by the icecap and exits the icecap ENE of the volcano. No explosive activity due to lava and river water interaction was observed, but steam rose from the area.

Figure 6. Lava fountaining, lava flows, and plumes emerging from Holuhraun on 6 September 2014, as viewed by NASA’s Landsat 8. Much of the flow was in lava rivers on the surface during September. Courtesy of NASA Earth Observatory.
Figure 7. Aerial view Bardarbunga fissure eruptions taken on 4 September 2014. The fissure venting these eruptions is in Holuhraun lava field. Courtesy of Peter Hartree (peter@reykjavikcoworking.is).

During 8-9 September, activity was no longer detected from the southernmost fissure. Lava continued to advance and interact with the Jökulsá á Fjöllum river. The extent of the lava flow reached 19 km2 and gas emissions remained high.

During 10-16 September, lava flows continued to advance at a consistent rate toward the E and W. A report on 22 September noted that the total volume of the erupted lava was 0.4-0.6 km3 and the flow rate was 250-350 m3/sec. By 30 September, the lava field was 46 km2, and the main flow had entered the river bed of Jökulsá á Fjöllum and continued to follow the river’s course. Steam rose from the river where the lava was in contact with water but no explosive activity occurred.

Although reporting noted a lack of tall mobile ash plumes blown towards Europe and causing air traffic delays, the plumes remained lower and more local causing widespread air quality problems in Iceland. IMO reported continued gas emissions that included elevated SO2 emissions during 10-16 September and issued warnings to the public in the municipality of Fjarðarbyggð (180 km ENE of Bardarbunga) on 13 September. These emissions persisted through at least November.

During 17-23 September, chemical analysis and geophysical modeling indicated that the source of the magma was at a depth of more than 10 km. On 21 September, field scientists estimated that about 90% of the SO2 from the eruption originated at the active craters and the rest rose from the lava field. Dead birds were also found around the eruption site.

Seismic activity at the N part of the dike and around the vents declined in October 2014, although the lava field continued to grow and lava production continued at the same output. On 5 October, a new lava front emerged at the S edge of the main lava flow and advanced E.

On 18 October, an M 5.4 earthquake struck in the N part of Bardarbunga caldera, one of the biggest earthquakes since the start of the eruption. The growing lava field at Holuhraun was 66 km2 by 31 October. By late October, the fissure’s main vent (Baugur crater) had constructed a local topographic high that stood 80 m higher than the local landscape.

In November, eruption-associated seismicity remained strong although an IMO report on the 19th suggested that the number of large, M~5 events seemed to be decreasing. FLIR thermal images of the craters on 18 November showed that by then the most intense area of thermal convection was at a crater in the N part of the eruption site. On 20 November, observers characterized the eruption in the crater as pulsating explosions every 10-15 minutes, followed by a gush of lava down the main channel with splashing on either side. During 25-26 November, the activity was characterized as pulsating, with lava surging from the vent for 2-3 minutes at intervals of about 5-10 minutes. The upper parts of the lava channel developed a sinuous appearance owing to a series of bulges in the channel’s margins.

On 12 November, IMO indicated that it monitored gas releases from Holuhraun using DOAS and FTIR instruments to estimate the fluxes of SO2 and other gases in the volcanic cloud. In the first month and a half of the eruption, the average flux was 400 kg/s (~35,000 metric tons per day, t/d) with peaks up to 1300 kg/s (~112,000 t/d). The IMO calculated that, assuming a constant release of gas through 12 November, the eruption had injected into the atmosphere an amount of SO2 in the range 3.5–11.2 Mega tons, Mt (depending on whether the computed from the average or the peak flux).

On 27 November, observers indicated that a plume rose 3.1 km above the sandy plain. A thermal image from 1 December showed several changes to the lava field. In just over 24 hours there was a new lava extrusion at the NE margin that had traveled 450 m. A new flow traveled N in an area just W of the lava lake. One or more new flows also developed S of the lava lake. The lava field from this eruption was just over 75 km2.

In early December, data also showed a decline in the eruption’s intensity, although seismic activity remained strong. By 9 December, the lava field at Holuhraun had covered just over 76 km2, making its aerial extent the second largest in Iceland (but still considerably smaller than the largest historical field created by the Laki fissure eruption of 1783-1784). By 18 January 2015, the lava covered an area of 85 km2. A NASA photo of the lava flow is shown in figure 8. The vent area contained a lava lake, a large mass of highly radiant (molten, red-colored) lava.

Figure 8. NASA image of the Bardarbunga eruption venting at Holuhraun on 3 January 2015, as captured by the Operational Land Imager on Landsat 8. According to the NASA caption, the false-color images combine shortwave infrared, near infrared, and red light. The dark area represents newly-formed basalt associated with the 2014-2015 eruption. The plume of steam and sulfur dioxide appears white, while fresh lava is bright orange. Courtesy of NASA Earth Observatory.

According to the IMO, the ongoing eruption’s very gas-rich emissions had affected the entire country. IMO stated that “we have to go 150 years back to find an event (Trölladyngja) that had a comparable impact on Iceland and its inhabitants, in terms of environmental and health issues.”

Radar measurements of the flow field during a surveillance flight on 30 December 2014 provided preliminary evidence that lava thickness averaged ~10 m in the eastern part, ~12 m in the center, and at least 14 m in the western part. IMO indicated that the preliminary estimate of the lava volume was 1.1 km3. (A later estimate in 2015 took the volume to 1.4 km3, roughly 10% of the Laki fissure eruption.)

IMO reported that during 31 December-6 January fresh lava flowed N and also to the E where in part it transited through a closed channel (shallow lava tube). During 7-20 January 2015, IMO noted that the lava field expanded along its N and NE margins. Seismicity remained strong and local air pollution from gas emissions persisted. IMO said that on the days10 and 15 January the lava field covered 84.1 and 84.3 km2, respectively.

Figure 9 shows the eruption on 21 January 2015.

Figure 9. Photo taking on 21 January 2015 showing the Bardarbunga’ eruption site at Holuhraun, including fissure vent, crater, lava flow, and plumes. The margins of the flow field are distinct in the distance, owing to snow cover. The main body of the flow field lies off the photo’s margin to the right. Courtesy of IMO (Morten S. Riishuus).

 

Subsidence. The caldera had been subsiding during the reporting period. The subsidence at Bardarbunga caldera was visible on the ice surface and was interpreted as reflecting deformation of the caldera itself. The depression developed in a roughly bowl-shape area that, as of 20 January 2015, was about 80 km2 in area with a volume exceeding 1.5 km3.

Figure 10 shows the chronology of subsidence levels between 5 September 2014 and 30 December 2014. The subsidence in the center of the caldera was about 60 m by 20 January 2015, a value determined by comparing the ice surface elevation with that elevation at the same location before the beginning of the collapse. Gudmundsson states that the assumption is that the ice surface lies more or less passively on top of the bedrock in the caldera. As of 20 January, no evidence of major ice melting had been observed; however, increased geothermal activity on the caldera rims has resulted in ice depressions over the hot spots. Other ice depressions on the Dyngjujokull glacier were also observed, suggesting that small, short sub-glacial eruptions may have occurred there. According to Gunnar Gudmundsson, there was no evidence of a subglacial eruption within the caldera.

Figure 10. Topographic profiles plotted along a line across Bardarbunga’s caldera for 5 September-30 December 2014. The N-trending profile crosses the E-central caldera (see inset on middle panel). The ice surface (top of light blue area) was constrained by lidar in 2011. The y-axis terms hys (m) and metrar refer to elevation and subsidence (both in meters). Subsidence (colored lines) was measured by a GPS station on the glacier surface in the caldera’s center and by radar altimetry from aircraft. The bottom profile shows the overall picture with the caldera’s surface and the 30 December 2014 profile (maximum subsidence). Courtesy of the Institute of Earth Sciences, University of Iceland (Magnus Gudmundsson and Thordis Hognadottir).

During early December, IMO reported that the Scientific Advisory Board of the Icelandic Civil Protection had reviewed data from the beginning of the eruption to 3 December. They acknowledged that the subsidence rate had decreased during that time, dropping from highs of up to 80 cm/day down to 25 cm/day, with most of the subsidence concentrated at the caldera center.

 

References. Björnsson, H. and Einarsson, P., 1990, Volcanoes beneath Vatnajokull, Iceland: Evidence from radio echo-sounding, earthquakes and j kulhlaups, Jökull, no. 40, pp 147-168 (URL: http://jardvis.hi.is/sites/jardvis.hi.is/files/Pdf_skjol/Bardarbunga_greinar/bjornsson_and_einarsson_1990.pdf )

Carrivick, J and Gertisser, R, 2014, Bardabunga: eruption develops in Iceland, Geology Today, v. 30, Issue 6, pp. 205-206, November/December 2014, John Wiley & Sons Ltd.

Einarsson, P., B. Brandsdóttir, M. T. Gudmundsson, H. Björnsson, K. Grínvold, and F. Sigmundsson, 1997, Center of the Iceland hotspot experiences volcanic unrest, Eos Trans. AGU, 78(35),369–375, doi:10.1029/97EO00237.

Einarsson, B., 2009, Jökulhlaups in Skaftá: A study of a jökulhlaup from the Western Skaftá cauldron in the Vatnajokull ice cap, Iceland, Thesis for Master of Science in Geophysics degree, School of Engineering and Natural Sciences, Faculty of Sciences, University of Iceland, (URL: https://notendur.hi.is//~mtg/nemritg/BE-MS_2009.pdf)

Gudmundsson, A, Lecoeur, N, Mohajeri, N, and Thordarson, T, 2014, Dike emplacement at Bardarbunga, Iceland, induces unusual stress changes, caldera deformation, and earthquakes. Bulletin of Volcanology, vol. 76, no. 10, pp. 1-7.

Hartley, M. E., and Thordarson, T., 2013, The 1874–1876 volcano-tectonic episode at Askja, North Iceland: Lateral flow revisited. Geochemistry, Geophysics, Geosystems, vol. 14, no. 7, pp. 2286-2309.

Ialongo, I., Hakkarainen, J., Kivi, R., Anttila, P., Krotkov, N. A., Yang, K., & Tamminen, J., 2015, Validation of satellite SO2 observations in northern Finland during the Icelandic Holuhraun fissure eruption. Atmospheric Measurement Techniques Discussions, vol. 8, no. 1, pp. 599-621.

IES, uncertain publication date, The Gjálp eruption in Vatnajokull 30/9 - 13/10 1996, Institute of Earth Sciences (IES), University of Iceland, Accessed on 31 March 2015 (URL: http://earthice.hi.is/gjalp_eruption_vatnajokull_309_1310_1996) .

Larsen, G. and Gudmundsson, M. T., 2014, Volcanic system: Bárðarbunga system, pre-publication extract from the Catalogue of Icelandic Volcanoes, Accessed on 4 April 2015, (URL: http://blog.snaefell.de/images/Bardarbunga_kafli20140825.pdf).

Icelandic Meteorological Office, 2010, List of recent volcanic eruptions in Iceland, Accessed on 31 March 2015 (URL: http://en.vedur.is/earthquakes-and-volcanism/articles/nr/1874).

Marteinsson, V.T., Rúnarsson, Á., Stefánsson, A., Thorsteinsson, T., Jóhannesson, T., Magnússon, S.H., Reynisson, E., Einarsson, B., Wade, N., Morrison, H., and Gaidos, E., 2013, Microbial communities in the subglacial waters of the Vatnajokull ice cap, Iceland, The ISME Journal, vol. 7, pp. 427–437, doi:10.1038/ismej.2012.97, (URL: http://www.nature.com/ismej/journal/v7/n2/full/ismej201297a.html ).

Seibert, L., Simkin, T., and Kimberly, P., 2010, Volcanoes of the World (Third Edition), pp. 204-205, University of Cailfornia Press, ISBN 978-0-520-26877-7.

Geologic Background. The large central volcano of Bárdarbunga lies beneath the NW part of the Vatnajökull icecap, NW of Grímsvötn volcano, and contains a subglacial 700-m-deep caldera. Related fissure systems include the Veidivötn and Trollagigar fissures, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. Voluminous fissure eruptions, including one at Thjorsarhraun, which produced the largest known Holocene lava flow on Earth with a volume of more than 21 cu km, have occurred throughout the Holocene into historical time from the Veidivötn fissure system. The last major eruption of Veidivötn, in 1477, also produced a large tephra deposit. The subglacial Loki-Fögrufjöll volcanic system located SW of Bárdarbunga volcano is also part of the Bárdarbunga volcanic system and contains two subglacial ridges extending from the largely subglacial Hamarinn central volcano; the Loki ridge trends to the NE and the Fögrufjöll ridge to the SW. Jökulhlaups (glacier-outburst floods) from eruptions at Bárdarbunga potentially affect drainages in all directions.

Information Contacts: Icelandic Met Office (IMO) (URL: http://en.vedur.is/); London Volcanic Ash Advisory Centre (URL: http://www.metoffice.gov.uk/aviation/vaac/); Institute of Earth Sciences (IES), University of Iceland (URL: http://earthice.hi.is); Pall Einarsson, IES, University of Iceland; Gunnar Gudmundsson, IMO; Magnus Tumi Gudmundsson, IES, University of Iceland (URL: http://earthice.hi.is); National Commissioner of Police, Department of Civil Protection and Emergency Management (URL: http://avd.is/en/): NASA Earth Observatory (URL: http://earthobservatory.nasa.gov).

Klyuchevskoy

Russia

56.056°N, 160.642°E; summit elev. 4754 m

All times are local


Two eruptive pulses: 15 August-20 December 2013 and 1 January-24 March 2015

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During mid-2013 to early 2015, Klyuchevskoy had two strong eruptive pulses with an intervening lull. The first pulse occurred 15 August-20 December 2013 (~3 months of eruption). Ash plumes and related eruptive activity halted during 2014 until about January 2015 (12 months pause). The second pulse occurred very late December 2014 or very early January 2015 through at least 24 March 2015 (~3 months of eruption).

We start by discussing the latter portion of the first pulse, covering the interval 15 November to 20 December 2013. That time period was missing from our earlier reporting, which ended with our last report (BGVN 38:07) summarizing eruptions during October 2012 through 14 November 2013.

In a later subsection labeled “2015,” we discuss the second of the two eruptive pulses. The Global Volcanism Program requires an eruptive repose of three or more months before an eruption is considered to be over; thus, at the time of this writing (6 April 2015), it is too early to tell whether 24 March will hold true as the end date for the later pulse.

We base this report on the reporting interval from the Kamchatkan Volcanic Eruption Response Team (KVERT). Table 15 in BGVN 38:07 delineates the Aviation Color Code (a four-step code from a low of Green, advancing from Yellow to Orange, and ultimately to a high of Red). Klyuchevskoy is also spelled alternatively Kliuchevskoi, Klyuchevskaya Sopka, and Klyuchevskaya.

Late 2013 activity (and lull during 2014). KVERT documented that eruptions were common during 15 August 2013-20 December 2013 (continuing for about 5 weeks beyond our last Bulletin report).

Figure 16 shows a photo taken on 16 November 2014 (UTC) by an astronaut aboard the International Space Station. This low angle image highlights some interesting plume dynamics–whereby the dark material at left branches off from a lighter colored plume trending farther to the right (heading ESE)). A NASA Earth Observatory article (posted in 2 December 2013) commented: “The plume—likely a combination of steam, volcanic gases, and ash—stretched to the [ESE] due to prevailing winds. The dark region to the [NNW] is likely a product of shadows and of ash settling out. Several other volcanoes are visible in the image, including Ushkovsky, Tolbachik, Zimina, and Udina. To the [SSW] of Klyuchevskoy lies Bezymianny Volcano, which appears to be emitting a small steam plume (at image center).”

Figure 16. A NE-looking photo taken from space at an oblique angle accentuating topography and showing the Klyuchevskoy eruption of 16 November 2013 (UTC). The image was taken when the ISS was located over a spot on Earth more than 1,500 km to the SW. The scene also labels additional volcanoes in the region (see text). Note N arrow at bottom left. This image and associated labels and interpretation came from the NASA Earth Observatory website (Photo identifier: ISS038-E-5515). Photo credits: Expedition 38 crew; with additional credit to the ISS National Lab and to original captioning information by William L. Stefanov, Jacobs Technology/ESCG, NASA Johnson Space Center, Houston, Texas.

During the reporting interval, KVERT issued multiple reports of a type called a VONA (Volcano Observatory Notices for Aviation), and they provide a record of eruptive activity at Klyuchevskoy. A VONA issued at 0242 on 17 November 2013 indicated that web camera assessments revealed strombolian eruptions with strong gas and steam; an ash plume rose to 7 km altitude and blew 160 km E. The four-step Aviation Color Code (low to high, Green, Yellow, Orange, and Red) rose to Orange. The VONA issued the next day at 0246 on the 18th (UTC) indicated significant decrease in eruptive activity, including a lack of ash plume during the last several hours, but with cautions that aerosols with ash were still possible at low altitudes.

Two VONAs were issued on 19 November 2013; the first at 0248 (UTC) raised the Aviation Color Code from Yellow to Red. This VONA noted that based on seismic data strong ash explosions had resumed at 0216 UTC on the 19th. Visual data showed ash plumes up to 10-12 km altitude extending unstated distances SE.

The VONA for 2341 on the 19th reported a lowered Color Code, to Orange, in response to lowered ash plumes (at 5-5.5 km altitude) during the previous several hours. The plumes blew unstated distances N and NE.

2014. The VONAs for December 2013 and into early January 2014 mentioned some still robust plumes, but the eruption ended on 20 December. A 3 December 2013 VONA indicated that an explosive eruption had seemingly stopped on 19 November, but this was ruled out by a 6 December VONA that again raised the Color Code to Red associated with strong ash plumes up to 5.5-6.0 km altitude and extending over 212 km NE of the volcano.

More information about the 3 December 2013 eruption came out in the 12 December WIR (emphasis added and plume length converted to kilometers): “Seismicity of the volcano increased on December 06, and began to decrease on December 10. Video data showed ash plumes rose up to [5-6 km altitude] on December 06-10. Satellite data showed a very weak thermal anomaly over the volcano summit; ash plumes extended about [1020 km in] the different directions [from] the volcano: to the [E] on December 06-08, to the [NW] on December 09-10, and to the [E and SE] on December 10-11 [2013].” This 1020 km long ash plume was among the longest documented during the reporting interval.

On 7 December a VONA announced the Color Code had dropped to Orange although explosive eruption continued. Video and satellite data revealed a 5.5-km-altitude, NE-directed plume of unstated length. Also, volcanic tremor remained at the previous level (0.7-1.0 mcm/s) and shallow volcanic earthquakes registered.

VONAs issued on 26 December 2013 and 2 January 2014 stated the eruption had ended. The later report noted the eruption end date of 20 December 2014.

No further VONAs were issued for Klyuchevskoy during the remainder of 2014.

2015. Late in 2014, KVERT reported that both the abundance and the magnitude of shallow volcanic earthquakes began to increase during 19-20 December 2014 and again on 31 December 2014; tremor became constant. The volcano was cloaked in clouds during 31 December 2014 to 1 January 2015, but KVERT judged that a strombolian eruption probably began on 1 January 2015, which is consistent with a satellite thermal anomaly. On 2 January 2015, the Aviation Color Code rose from Green (normal) to Yellow (which is a sign of elevated unrest). During the course of January 2015 the volcano resumed frequent eruptive activity and that month KVERT issued ~15 VONAs for Klyuchevskoy. The eruption stopped on 24 March 2015 and any later events after 6 April 2015 extend beyond the current reporting period.

Besides the VONAs, KVERT also creates Weekly Information Releases (hereafter WIRs). The WIR issued on 8 January 2015 stated that both strombolian explosive eruptions of the volcano and associated incandescence continued. Lava bombs rose up to 200-300 m above the crater and ash plumes to ~5 km altitude. Seismic activity of the volcano continued to increase. The magnitude of tremor increased from 3 to 13 x10-5 m/sec. (Note that KVERT reported tremor in units reflecting the velocity of the seismic sensor. They state these units as “mcm/s,” ‘milli-centimeters per second’, which are equivalent to 10-5 m/sec, the means of expression used in this report.) Video data on the 4th and 7th revealed strong gas-steam emissions. Clouds obscured the volcano during other days of the week. Satellite infrared data showed a bright thermal anomaly over the volcano all week.

KVERT’s 16 January WIR noted clear visibility of the summit area where bombs were ejected 200-300 m above the summit crater. Strombolian and vulcanian eruptions produced a series of ash plumes that rose to 5-8 km altitude (table 16). The Aviation Color Code increased to Orange.

Figure 17 shows a strombolian eruption at the summit on 19 January 2015. The KVERT caption reported that at this time two centers of strombolian activity and lava flows could be observed at the summit crater. About a week before, video images suggested a new lava flow had started to discharge downslope, and by mid-January through March, lava flows were regularly indicated in KVERT reports (two were seen on the NW slope on 15 March).

The lava flows led to phreatic explosions at the lava flow front. These produced gas-and-steam clouds with minor amounts of ash that during 27-28 January rose to an altitude of 7-8 km. Ashfall was reported in nearby (table 16). Consistent with the lava flows and the spatter from strombolian eruptions, satellite images consistently showed thermal anomalies over the volcano.

Figure 17. Photo of Klyuchevskoy taken during strombolian emissions on 19 Jan 2015. Strombolian activity with bombs rose to heights of 200-300 m and were common around this time (see table 16). Courtesy of Yu. Demyanchuk, IVS FEB RAS, KVERT.

On 15 February, a series of explosions generated ash plumes that rose to an altitude of 8 km, prompting KVERT to raise briefly the Aviation Color Code to Red. Later that day, it was lowered to Orange. During the second half of February, bombs were ejected 150 m above the crater, rather than up to ~300 m, as earlier. Towards the end of February they were no longer reported although that may have been due to lack of visibility or the spatter and bombs may have decreased in size to the point where such emissions became difficult to observe.

On 9 March, the magnitude of seismic tremor significantly decreased. Only moderate emissions of steam and gas were observed, and a thermal anomaly over the summit disappeared. The Aviation Color Code was lowered to Yellow. On 10 March, seismic tremor significantly increased again, prompting KVERT to raise the Aviation Color Code to Orange. Video images showed moderate gas-and-steam activity, while satellite images detected a gas-and-steam plume with small amounts of ash. During 10-17 March, a weak thermal anomaly was detected occasionally over the summit. The eruption continued through the middle of March, but the energy of the explosions decreased significantly, prompting KVERT to lower the Aviation Color Code to Yellow on 25 March.

As of 2 April 2015, KVERT reported that moderate activity continued, with strong fumarole activity. As previously mentioned, KVERT described the explosive eruption as ended on 24 March (table 16).

Table 16. Plume characteristics at Klyuchevskoy during 10 January to 2 April 2015 (UTC). NR means not reported, Bhgt stands for the height above the crater to which bombs were thrown (in meters). Data do not include low-rising emissions. Bolded cases represent noteworthy events; not reported, NR. KVERTs satellite-based assessment of the ash content in plumes was generally determined by methods discussed by Ellrod (2012) and Ackerman and others (undated) and references therein. The table was assembled largely from KVERT VONAs and their Weekly Information Releases (WIRs).

Time period Max. ash plume altitude (km) Drift length and direction
Remarks
1-11 Jan 2015 NR NR

(2nd) VONA this day (the only one until the 11th) reported strong and moderate gas-steam plumes during past weeks. Weak thermal anomaly at both the summit and at a SW-flank. Seismically active.

WIR issued on 2nd noted that explosive eruption probably continued, and a thermal anomaly appeared on the 1st. Weather clouds often masked visibility. WIR issued the 11th noted strong gas-and-steam emissions and strombolian eruptions. Bhgt 200-300 m. Thermal anomaly, but absence of ash plumes during past week. Clouds often blocked views. Aviation Color Code (2nd and 11th): Yellow

12-15 Jan 5-7 (11-15th) In general, 160 km SW and NE

On 11th, ~35 km @ 5 km alt. SSE WIR issued 16 Jan noted the following: Moderate explosive activity. Ashfall in Kozyrevsk village. Bhgt 200-300 m. Thermal anomalies all week. Intervals of increased seismicity and tremor. Aviation Color Code: mainly Orange through 20 March

(10-12th) Strong explosive events; ash clouds rose up to 6-10 km alt., strong ashfall on 12th at Klyuchi village (~50 km W of volcano).

(10-12th; 15-16th) Ash plumes drifted over 200 km W and SW of volcano.

16-22 Jan 5-7 210 km SW, NW, NE

WIR issued 23 Jan noted the following: Moderate explosive activity. Bhgt: 200-300 m. Satellite IR thermal anomaly was consistent with hot lava. E flank lava flow noted.

(21st) Ashfall in Klyuchi village.

23-29 Jan 5.5-7 & more (at right) 300 km various (W, N, NE, E, and SE)

WIR issued 30 Jan noted the following. Moderate explosive activity. Good summit visibility; incandescence and thermal anomaly all week. Bhgt: 200-300 m. E flank lava flow.

(27-28th) Phreatic explosions at the advancing E-flank lava front produced gas-and-steam plumes with minor amounts of ash that rose to 7-8 km. Ashfall on 27th both in Klyuchi village and near the Khapitsa river, and on 28th in Kozyrevsk village.

30 Jan-4 Feb 5-6 Various during week. (4-5th) 1,000 km NW and N

WIR issued 5 Feb noted the following. Moderate explosive activity. Ongoing strombolian and vulcanian eruptions all week; Bhgt 200-300 m; advancing E flank lava flows and consistent thermal anomalies.

(5th) Ashfall in Klyuchi village.

5-12 Feb 5.5-6.5 400 km, mainly NW and N

WIR issued 13 Feb noted the following. Moderate explosive activity. Ongoing strombolian and vulcanian eruptions all week. On 7th, ashfall in Kozyrevsk village and on 11th in Klyuchi village. Bhgt 200-300 m.

13-20 Feb 5-8 Up to 600 km, mainly E, SE, and S during week WIR issued 21 Feb noted strombolian and vulcanian eruptions: Bhgt: 150 m. (13-16th) Ashfall in Klyuchi village (temporary elevation of Avaiation Color Code to Red).
21-27 Feb 5-6 90 km NE

WIR issued 28 Feb noted continuing strombolian and vulcanian eruptions and ash explosions. Bhgt not reported in this or later WIRs.

28 Feb-5 Mar 5-6 400 km, mainly E, SE, and NE during week

WIR issued 6 Mar noted moderate eruption continued and still included strombolian and vulcanian eruptions, ash explosions, and summit glow. Thermal anomalies all week.

6-11 Mar 5-6 (8th and 10th) ~338 km broadly E

WIR issued 12 Mar noted moderate explosive eruptions continued this week. Thermal anomalies on 7th and 10-11th. (9th) Moderate emissions of steam and gas; (10th) similar to 9th but with minor ash.

12-20 Mar 5-5.5 90 km, broadly E

WIR issued 20 Mar noted moderate ongoing eruption but significantly weaker than in previous weeks. Thermal anomaly weak. Better visibility during 16-17th, poor on other days.

(16-17th) (includes observations to left); poor visibility on other days;.) Aviation Color Code Orange

21-26 Mar NR NR WIR issued 27 Mar: End of explosive eruption on 24th. Strong fumaroles persisted. Gas-steam plumes containing small amounts of ash on 22nd-23rd. Weak thermal anomaly all week. Aviation Color Code, Yellow.
27 Mar-6 April NR NR

WIR issued on 3 Apr stated that strong fumarolic activity and weak thermal anomalies both continued, but that clouds blocked view except for 30th. VONA was issued on 6th: Both high seismicity and moderate gas-steam emissions continued. Aviation Color Code on 3rd Yellow, changing on 10th to Green.

 

 

References:

Gary Ellrod, 2012, Remote Sensing of Volcanic Ash, National Weather Association website (URL: http://www.nwas.org/committees/rs/volcano/ash.htm )

Ackerman, S., Lettvin, E, Mooney, M, Emerson, N, Lindstrom, S, Whittaker, T., Avila, L, Kohrs, R, and Bellon, B., undated, Satellite applications for geoscience education [online course; Facilitating the use of satellite observations in G6-12 Earth Science Education] University of Wisconsin and University of Washington (URL: https://cimss.ssec.wisc.edu/sage/geology/lesson3/concepts.html ).

Geologic Background. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Information Contacts: Kamchatka Volcanic Eruption Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/ ); Kamchatka Branch, Geophysical Service, Russian Academy of Sciences (KB GS RAS)(URL: http://www.krsc.ru/english/network.htm); NASA Earth Observatory (URL: http://earthobservatory.NASA.gov/); and William L. Stefanov, Jacobs Technology/ESCG, NASA Johnson Space Center, Houston, Texas.

Merapi

Indonesia

7.542°S, 110.442°E; summit elev. 2968 m

All times are local


During June 2011 to December 2014, several eruptions and elevated seismicity

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This report details activity and monitoring at Merapi from 13 June 2011 through December 2014.

The last major eruption at Merapi was in 2010 as discussed in the previous two reports. As noted in BGVN 36:01 (covering 26 October 2010 to January 2011), Merapi began to erupt on 26 October 2010 and continued erupting throughout the interval, causing ~400 fatalities. BGVN 36:05 (26 October 2010 to 12 June 2011) further discussed this eruption detailing new dome growth and how lahars damaged infrastructure.

During the current reporting interval (13 June 2011 through December 2014), Merapi erupted regularly amid elevated seismicity. This report chiefly derives from three sources: (1) Balai Penyelidikan dan Pengembangan Teknologi Kegunungapian (BPPTK), (2) Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG; here referenced as CVGHM which stands for Center for Volcanology and Geological Hazard Mitigation), and (3) the Darwin Volcanic Ash Advisory Center (VAAC).

 

2011.The hazard status for Merapi from 13 June 2011 onwards was Alert, Level II (on a scale of I–IV), before it decreased during 12–18 September 2011 and remained at Normal, Level I. Several minor avalanches occurred, with noted incidents on 2, 4, 6, 7, 14, and 25 July; 2, 7, and 15 August; and 4 and 8 September. Merapi also released several plumes, most of which consisted of white, thin or thin-to-thick clouds that rose to a maximum of only a few hundred meters above the summit (table 21).

Table 21. From 13 June to 31 December 2011, the plumes released by Merapi were generally described as thin or thin-to-thick and white in color. The only exception was apparent puffing associated with the plume on 10 July 2011, which lasted ~3 hours. Courtesy of BPPTK weekly reports from 2011.

Date Time (Local Time) Max. height above the crater(m)
19 Jun 2100 200
3 Jul 2015 600
4 Jul 2043 600
10 Jul 2100–2400 200
16 Jul 2115 400
18 Jul 1750 350
25 Jul 1510 400
7 Aug 2150 400
10 Aug 2028 600
18 Aug 2015 200
3 Sep 3002 350
8 Sep 1950 100
16 Sep 1650 200
10 Oct 1805 150
23 Oct 1740 125
26 Oct 1840 100
6 Nov 1456 400
9 Nov 1720 400
2 Dec 1740 150
5 Dec 1700 200
14 Dec 1929 900
31 Dec 2110 90

The non-tremor seismicity at Merapi in 2011 (figure 54) was categorized into four types of earthquakes, each of which had different patterns on the time-series plots. The seismicity was also described in terms of Real-time Seismic Amplitude Measurement (RSAM), (not shown here). In 2011, avalanche earthquakes and multiphase earthquakes dominated the record.

Figure 54. Number of earthquakes (“Jumlah Kejadian” in Indonesian) recorded at Merapi for 2011 with shallow volcanic (VB, green), deep volcanic (VA, red), avalanche (“Guguran,” purple), and multiphase (MP, orange) earthquakes. The terms shallow and deep were not quantified. Note that the y-axis scales vary such that the most numerous earthquakes were MP and avalanche, and the least numerous were VB and VA. Courtesy of BPPTK (taken from their 2–8 January 2012 weekly report).

A key means of measuring changes in linear length at Merapi consisted of surveys employing Electronic Distance Measurement (EDM) instruments (figure 55). The instruments computed the distance from several reflectors positioned on Merapi’s slopes to fixed points at surrounding observatory posts. Figure 56 (below) provides the location of the posts and reflectors mentioned. Length changes were generally in the range of a few centimeters.

Figure 55. EDM linear length at Merapi in 2011, based on the distances from specified reflectors to various fixed locations. “Jarak” signifies distance (in meters). (A) 1 July to 30 December, recorded by Post Babadan. (B) 1 July to 9 December, recorded by Post Kaliurang. (C) 1 July to 5 December, recorded by Post Jrakah. The EDM linear lengths between the Post and both reflectors were broadly similar. (D) 1 July to 5 December, recorded by Post Selo. Courtesy of BPPTK (26 December 2011–1 January 2012 report).
Figure 56. Images highlighting the locations of Merapi’s observation posts (left) and reflectors (right). The right image is a zoomed-in version of the summit area (approximate red rectangle on the left image). To provide scales, the distance (in the image at left) from the summit to Kantor BPPTKG is ~30 km and the distance (in the image at right) from Jrakah 1 to Deles 3 is ~300 m. Courtesy of BPPTK (page titled Aktivitas Merapi), image captioned by Bulletin editors.

 

2012. A thin, white plume rose to a maximum of 150 m above the crater at 1910 on 6 January, and storms and heavy clouds covered Merapi’s summit. On 9 January at an unstated time, a photo from CCTV Deles (discussed by BPPTK) showed Merapi amid clear weather with a white billowing cloud rising from the crater area. A few days later, at 1835 on 15 January, Merapi ejected a thin, white plume, rising to a maximum of 100 m above the summit, heading W.

Thin, white plumes were also observed above the crater to 50 m, heading E on 1 February at 1720; to 500 m at 1745 on 11 February; and to 400 m at 1800 on 13 February.

During 30 July to 5 August 2012, BPPTK referred to thick, white plumes drifting from the volcano. One plume reached a maximum of 600 m above the crater at an unstated date around this time.

For the intervals in 2012 discussed above, the hazard status remained constantly at Normal (I). Furthermore, during 2012, the BPPTK recorded the seismicity (figure 57) and the EDM linear length (figure 58).

Figure 57. Number of earthquakes (“Jumlah Kejadian” in Indonesian) at Merapi for 2012 with low-high frequency (LHF, pink), shallow volcanic (VB, green), deep volcanic (VA, red), avalanche (“Guguran,” purple), and multiphase (MP, orange) earthquakes. The numbers/peaks for each type of earthquake did not follow the same pattern. Note that the numbered scales on the left side vary. Courtesy of BPPTK (28 January–3 February 2013 report).
Figure 58. Merapi’s EDM linear length in 2012, based on the distances from reflectors to various fixed locations. “Jarak” signifies distance (in meters). The measurements were recorded by Selo, Jrakah, Kaliurang, and Babadan stations (top to bottom). The sudden shift in the trend and the words “Setting ulang alat” (red words on the topmost graph) refer to technicians resetting the scale at that time (the instrument remained stable). Courtesy of BPPTK (28 January–3 February 2013 report).

 

2013. A thick plume blew W and reached a maximum of 450 m above the crater at 1750 on 3 February. The hazard status was at Normal (I).

On 22 July at 0415, BPPTK observed an ash eruption with brown-to-black color, reaching 1 km above the crater. A roar was heard within a radius of 6–7 km around Merapi, and ash fell to the SE, S, and SW. The hazard status remained at Normal (I); the Aviation Color Code was at Orange. According to a news article (Yahya, 2013), the eruption caused hundreds to temporarily evacuate; they returned to their homes later the same day.

On 29 October 2013, BPPTK observed a white, thin-to-thick plume that reached 150 m above the summit, heading W.

On 18 November 2013, Merapi erupted. A news article in the Jakarta Post discussed the event extensively quoting BPPTK staff (Muryanto and Ayuningtyas, 2013). The article said that the eruption began at 0453 LT forming a plume that rose to 2 km above the crater. Ash fell until about 1000 that day, with noticeable amounts found up to 60 km to the E. The news report also noted that ~600 families “in Kalitengah Lor, Kalitengah Kidul and Srune hamlets, and in Glagaharjo village, Sleman regency, Yogyakarta, had immediately gathered to be evacuated” and that “villagers in Turgo village, Turi district, Sleman, located on the western flank of Mount Merapi, also fled their homes, [returning] a few hours later as the situation returned to normal.” The eruption followed an M 4.7 tectonic earthquake detected in Ciamis, West Java earlier that day and was more powerful than a previous eruption on 22 July 2013 (Muryanto and Ayuningtyas, 2013).

Based on a Darwin VAAC report at 2025 LT on the same day (18 Nov), the eruption formed a plume that reached ~12.2 km altitude. The Aviation Color Code was increased to Red. By 2104 on the 18th, VAAC satellite analysis no longer detected the high altitude volcanic plume, but the VAAC reported a lower plume at ~4.6 km altitude. At 0300 on 19 November, the low level plume had extended to ~46 km E. However, by 0735, the plume had completely dissipated, and the Aviation Color Code returned to Orange.

BPPTK noted the seismicity (figure 59), the EDM linear length (figure 60), and the tilt (figure 61). In 2013, seismicity was dominated by avalanche earthquakes (figure 59). The only major change in linear length was the distance to Kaliurang 2 which had a gradual upward trend for most of the year, before a comparatively rapid downward trend in mid-October (figure 60). The two tiltmeter records showed broad consistency, with mild increases in the middle to late part of the year that reverted near to the original tilt (figure 61). The temperature graph had a broad peak in August 2013 that could account for some of the increase in tilt, but the BPPTK report did not discuss this in any detail. (For the location of the tiltmeter stations mentioned, see figure 62.)

Figure 59. Number of earthquakes (“Jumlah Kejadian” in Indonesian) in 2013 at Merapi for low-to-high frequency (LHF, pink), deep volcanic (VA, red), shallow volcanic (VB, green), multiphase (MP, orange), and avalanche (“Guguran,” purple) earthquakes. Y-axis scales vary. Courtesy of BPPTK (17–23 January 2014 report).
Figure 60. Merapi EDM linear length recorded during 2013, based on the distances from reflectors to various fixed locations. “Jarak” signifies distance (in meters). The measurements were recorded using reflectors Selo 1, Jrakah 1, Kaliurang 2, and Babadan 1 (top to bottom). Courtesy of BPPTK (25–31 October 2013 report).
Figure 61. Tilt recorded at Merapi’s station Plawangan. Y-axis units for the upper two tilt plots are microradians (arbitrary values). “Sumbu X” refers to tilt along a line running E-W and “Sumbu Y” to tilt along a line running N-S. The bottom plot is “Suhu” or temperature in degrees Celsius, which CVGHM noted may have a strong impact on the tilt measurements. Courtesy of BPPTK (17–23 January 2014 report).
Figure 62. The location of the tiltmeter stations. To provide a scale, the distance from Klatakan Analog to Pusunglondon is ~0.9 km. Courtesy of BPPTK (Aktivitas Merapi).

 

2014. BPPTK noted that on 17 January at 1615, a white plume rose to 50 m above the summit, heading E.

At 1854 LT on 10 March 2014, Merapi erupted forming an ash plume that blew W. The event was captured on an automated closed-circuit video (CCTV Pasarbubar) and was followed by two more blasts within a minute (the first at 1855). At 1908, BPPTK noted a volcanic earthquake (with a maximum amplitude of 20 cm). Another video monitor (CCTV Bubar) recorded brown eruptive columns that rose straight up, reaching up to ~1.5 km above the summit. During 1925 to 1930, the eruption gradually stopped. Around this time, ash fell on several villages including Umbulharjo, Kepuharjo, Sidorejo, and Balerante, areas located ~6–7 km to the S of Merapi.

During 14–20 March 2014, thick gas plumes rose to ~600 m above the summit. On 17 March, the BPPTK recorded one such event at 0530.

On 27 March 2014, an eruption lasted from 1312 to 1316 LT. The VAAC detected volcanic ash to ~9.8 km altitude, using multi-spectral MTSAT-2 imagery, and the Aviation Color Code was raised to Red. A pilot reported that the “large ash cloud [was] moving NW.” Darwin VAAC received a SACS SO2 alert at 2150 for the plume, and atmospheric SO2 gas was detected SE of Merapi. By 2232, the volcanic ash appeared to be dissipating; the advisory was terminated at 0830 on 28 March.

The 27 March eruption was the subject of a Jakarta Post news article by Muryanto and Ayuningtyas (2014), who indicated that ash fell in the Kemalang and Balerante Klaten regency and that it was 1 mm thick in some areas. The article also noted an M 5.4 tectonic earthquake that struck ~115 km SE of Malang regency, East Java on 23 March. The ash discharge had apparently been occurring regularly since the 2010 eruption but authorities had not taken this as a sign of an escalation in activity, and they urged locals to remain calm. However, according to the article, Sukiman, a resident of the nearby Deles district, said villagers responded to half an hour of ash falling by hitting “kentongan [bamboo drums] to warn others of the danger.”

On 15 April, BPPTK reported that a thick white plume rose to a maximum of 300 m above the summit.

Several tectonic earthquakes occurred in April 2014. On 18 April at 2033, BPPTK recorded tectonic earthquakes 151 km SW of Merapi at a depth of 10 km. On 19 April, four more tectonic earthquakes occurred between 0800 and 2000, and an earthquake lasting 20 minutes was recorded at 0421 from a station on the peak of Merapi. On 20 April from 0426 to 0440, rumbling could be heard within a radius of 8 km around the volcano.

The BPPTK reported that on 20 April at 1600, an ash plume traveled W towards the village of Sewukan, amid foggy conditions. The associated eruption was followed by a widely heard roar and a later thin-to-thick plume rose to 400 m above the summit at 1800. The activity ultimately led to ashfall in Sewukan and in sectors to the SE, S, and SW, up to 15 km away from Merapi’s summit.

The ash from this eruption was also detected by Darwin VAAC, who stated that the ash plume rose to ~10.7 km and extended ~260 km W to NW. The ash was difficult to distinguish from meteorological clouds, and at 1004 LT on 21 April, the VAAC terminated the advisory. In a news article, Minggu (2014) added further details on the eruption omitted here.

The BPPTK conducted a field expedition on 22 April to Merapi’s crater. The expedition found that the eruption on 20 April had changed the summit crater morphology (figure 63). The slit that cut through the lava dome trending NE had widened by 70 m to the W, and reddish material that the team judged as indicative of oxidation was visible around the center of the lava dome. They also found new eruptive products along the crater’s W side and evidence of new growth at the lava dome.

Figure 63. Field observations made on 22 April 2014 of Merapi’s crater, assessing the aftermath of the 20 April eruption. (Top) View through the NW slit in the dome’s crater. The crater wall appears in the background. (Bottom) Blowup of region depicted by base of red arrow. A wall in the summit crater area shifted W by ~70 m. New deposits were found in the area on the far side of the yellow dashed line. Courtesy of BPPTK (18–24 April 2014 report), image re-captioned in English by Bulletin editors.

The BPPTK reported that monitoring outposts heard as many as 47 thumping sounds between 25 April and 1 May 2014, 20 sounds between 2 and 8 May, and 22 sounds between 9 and 15 May. On 25 April at 0740, a white, fumarolic plume rose to a maximum of 450 m above the summit, heading W, and the hazard status was raised to Alert (II). White, thin-to-thick plumes rose above the summit to 650 m on 2 May at 0700; to 350 m on 12 May at 0606; to 450 m on 22 May at 1924; to 300 m, heading W, on 27 May at 1854; and to 400 m on 31 May at 2010. The hazard status was lowered to Normal (I) during 21–27 May.

On 4 July 2014 at 1754, BPPTK observed thin-to-thick white plumes rising to 450 m above the summit.

On 10 September at 2008, thin, white plumes rose to 200 m above the summit, according to BPPTK.

During 10 to 16 October, Merapi released a thin white plume to ~200 m above the summit. The Darwin VAAC noted that small rock avalanches extended for ~1 km.

For 2014, BPPTK noted the seismicity (figure 64), EDM linear length (figure 65), and tilt (figure 66).

Figure 64. Number of earthquakes (“Jumlah Kejadian” in Indonesian) registered at Merapi for 2014. Note that the y-axis scales vary. (Top) Chart covers from January to September 2014 and consists of earthquakes: volcano-tectonic (TEK), low frequency (LF), low-to-high frequency (LHF), volcanic (VUL), multiphase (MP), and avalanche (GGR). (Bottom) Chart covers from October to December 2014 and consists of tremors (VT) and earthquakes: multiphase (MP), rock fall signals (RF), and tectonic (TT). Courtesy of BPPTK (5–11 September 2014 and 20–26 March 2015 reports).
Figure 65. Merapi EDM linear length in 2014, based on the distances from reflectors to Post Kaliurang. “Jarak” signifies distance (in meters). The top chart covers from January to September and the bottom from October to December. (Date format for bottom is day/month/year.) Courtesy of BPPTK (5–11 September 2014 and 20–26 March 2015 reports).
Figure 66. Tilt registered at Merapi in 2014 (y-axis/microradians with arbitrary values). (Top) January to September 2014, based on recordings made at stations Plawangan (left) and Babadan (right). “Sumbu X” portrays tilt along an E-W direction and “Sumbu Y”, tilt along a N-S direction. The last plot (“Suhu”) in each of these two cases shows the temperature in degrees Celsius. (Bottom) October to December, based on recordings made by station Klatakan Analog. The red line represents (tangential) tilt in an E-W direction (“Sudut B-T”). The blue line represents (radial) tilt in a N-S direction (“S-U”). The sudden changes in the red and blue lines were caused by repositioning. Courtesy of BPPTK (5–11 September 2014 and 20–26 March 2015 reports).

 

Background. Several detailed maps of Merapi have been published by various sources. Handisantono and others (2002) contains a topographic hazard map of Merapi. The map includes the location of several villages mentioned in this report, as wells as rivers and other geological landmarks. BNPB also published a map of Merapi (figure 67). The map highlights the location of the W/SW/S-flank drainage systems, which have the potential to funnel lahars to local infrastructure such as bridges and into inhabited areas.

Figure 67. A section of a map of Merapi detailing lahars and related drainage systems (blue lines). The bounding color areas around the lahars represent associated hazard zones with risk levels ranging from yellow to red (least risk to most). Portions of concentric red, orange, and yellow circles mark the radial distance from Merapi’s summit in kilometers. Courtesy of BNPB (date unknown).

A detailed analysis of Merapi’s history and periods of activity is documented by CVGHM (2014). The ongoing magmatism and volcanism at Merapi are considered consistent with documented copper, zinc, and lead enrichment as well as zonation there (Nadeau and others, 2013).

 

References.

Badan Nasional Penanggulangan Bencana (BNPB), date unknown, Peta Zonasi Ancaman Banjir Laha Dingin, Relief Web (URL: http://reliefweb.int/sites/reliefweb.int/files/resources/E0676C85D7612CE1852578340054FD68-map.pdf) [accessed in April 2015]

CVGHM, 2014, G. Merapi, Jawa Tengah, 03 June 2014, Center for Volcanology and Geological Hazard Mitigation (URL: http://www.vsi.esdm.go.id/index.php/gunungapi/data-dasar-gunungapi/542-g-merapi) [accessed in April 2015]

Hadisantono, R.D., Andreastuti, M.CH.S.D., Abdurachman, E.K., Sayudi, D.S., Nurnusanto, I., Martono, A., Sumpena, A.D., Muzani, M., 2002, Peta Kawasan Rawan Bencana Gunungapi Merapi, Jawa Tengah Dan Daerah Istimewa Yogayakarta (Volcanic Hazard Map of Merapi Volcano, Central Java and Yogyakarta Special Province), Center for Volcanology and Geological Hazard Mitigation (URL: http://www.vsi.esdm.go.id/galeri/index.php/Peta-Kawasan-Rawan-Bencana-Gunungapi-01/Wilayah-Jawa/KRB-G_-Merapi) [accessed in April 2015]

Minggu, 2014, Mt. Merapi rumbles spewing volcanic material to nearby areas, 20 April 2014, Antara News (URL: http://www.antaranews.com/en/news/93713/mt-merapi-rumbles-spewing-volcanic-material-to-nearby-areas) [accessed in April 2015]

Muryanto, B., Ayuningtyas, K., 2013, Hundreds of villagers flee Mount Merapi eruptions, 19 November 2013, The Jakarta Post (URL: www.thejakartapost.com/news/2013/11/19/hundreds-villagers-flee-mount-merapi-eruptions.html) [accessed in April 2015]

Muryanto, B., Ayuningtyas, K., 2014, Mount Merapi spews sulfuric gas, ash, 11 March 2014, The Jakarta Post (URL: www.thejakartapost.com/news/2014/03/11/mt-merapi-spews-sulfuric-gas-ash.html) [accessed in April 2015]

Nadeau, O., Stix, J., Williams-Jones, A.E., 2013, The behavior of Cu, Zn and Pb during magmatic–hydrothermal activity at Merapi volcano, Indonesia, 29 March 2013, Chemical Geology Volume 342 (URL: www.sciencedirect.com/science/article/pii/S0009254113000466)

Yahya, A., 2013, Mount Merapi Status Remains Normal Despite Weak Eruptions, 22 July 2013, Bernama (URL: http://www.bernama.com/bernama/v7/ge/newsgeneral.php?id=965338) [accessed in April 2015]

Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi volcano during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities during historical time.

Information Contacts: Balai Penyelidikan dan Pengembangan Teknologi Kegunungapian (BPPTK), Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) (URL: merapi.bgl.esdm.go.id); Darwin Volcanic Ash Advisory Centre (VAAC) (URL: http://www.bom.gov.au/info/vaac/); and Center for Volcanology and Geological Hazard Mitigation (CVGHM, Pusat Vulkanologi dan Mitigasi Bencana Geologi), Badan Geologi, Kementerian Energi dan Sumber Daya Mineral (ESDM), Yogyakarta 55166, Indonesia (URL: www.vsi.esdm.go.id/).

Sinabung

Indonesia

3.17°N, 98.392°E; summit elev. 2460 m

All times are local


May-October 2014: Frequent eruptions, pyroclastic flows, and advancing lava-flow lobe

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May-October 2014: Frequent eruptions, pyroclastic flows, and advancing lava-flow lobe

As explained below, on the basis of ash-plume reports from the aviation community around the time of this reporting, Sinabung ranked as the most active volcano in Indonesia, the world's fourth-most populated country. The volcano is located in the Karo Regency of N Sumatra (figure 19). The latest eruption of Sinabung volcano began mid-September 2013; activity through April 2014 was reported in BGVN 39:01. This report describes the continuing volcanic activity from May 2014 through October 2014, primarily drawn from reports issued by the Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) and reports from the Darwin Volcanic Ash Advisory Centre (VAAC). During this reporting interval, many photographs of Sinabung emerged online, some with outstanding information content, but far too numerous to either catalog or feature here.

Figure 19. Sinabung is located in Karo Regency on the island of Sumatra in the Indonesian archipelago. Sinabung resides NE of the closest margin of Toba caldera, the largest volcano of this type known on Earth. The elongate caldera contains a lake 100 km long. The central portion of the lake is occupied by a prominent island (a classic resurgent dome). Taken from Darwin VAAC.

The Darwin VAAC describes their jurisdiction as covering ~150 active volcanoes located in the South Pacific region from the Philippines to the Solomon Islands, including Indonesia. They issued 1,511 Volcanic Ash Advisories (VAAs) during the 12-month period, 1 July 2013 to 30 June 2014 (their fiscal year 13/14; Darwin VAAC, 2014). During the next 7-month interval (ending 31 January 2015) the VAAC issued 742 reports (Darwin VAAC, 2015). These VAAs are part of their mission to create materials for warning and guidance to the aviation community, including aviation meteorologists, air traffic control offices, and airlines (e.g. dispatchers and pilots).

One way to assess the production of noteworthy ash plumes at volcanoes is to consider the number of VAAs issued, an assessment found in their Management Reports (Darwin VAAC, 2014; 2015). The Darwin VAAC issued Management Reports that both cover and extend beyond (i.e., both earlier and later than) this reporting interval (May to October 2014). Specifically, their reports cover 1 July 2013-30 June 2014 and 1 July 2014-31 January 2015. In both those intervals the largest number of VAAs issued for any single volcano in their region went to Sinabung. In the earlier interval this consisted of 537 out of 1,511 total regional reports; in the later interval, 321 out of 742 total regional reports.

The table in the section “Data compilation” at the bottom of this report also highlights a case at 12:32 UTC on 22 May 2014 of a rapidly growing cloud around Sinabung plausibly associated with an eruption there. The cloud reached ~15.2 km altitude and was initially assessed as eruptive and ash bearing. At the time forecasters felt there was sufficient evidence the cloud contained ash to warrant an advisory. A more detailed assessment made later determined the cloud to probably have been a cumulonimbus cloud (abbreviated Cb; a towering vertical dense cloud often associated with thunderstorms and atmospheric instability). The case illustrates the challenge of creating VAAs rapidly with limited information and time for analysis, balanced against the desire for high accuracy (with low rates of false positives and false negatives). Darwin VAAC (2015) also described the region as one with “. . . moist tropical convection that makes remote sensing difficult for much of the year.”

During the reporting interval, Sinabung was the scene of both lava flows and vigorous dome-building eruptions that discharged significant ash plumes and pyroclastic flows (PFs). Lava flows constructed a several kilometer long tongue or lobe of lava on the flank to the S-SE. These events accompanied elevated seismicity.

During the reporting interval the Aviation Colour Code (ACC) issued by the VAAC was generally Orange; however, during the week of 15-21 October, the ACC was Red.

The ACC is a four-color scale used to inform the needs of the aviation community. The four colors denoting increasing risk are Green, Yellow, Orange, and Red. According to the World Organization of Volcano Observatories’ website, Orange connotes “Volcano is exhibiting heightened unrest with increased likelihood of eruption.” Red connotes “Eruption is forecast to be imminent with significant emission of ash into the atmosphere likely.”

The CVGHM uses a separate volcanic hazard status code to warn people in the region. The Darwin VAAC Weekly report issued for 29 October-4 November 2014 gave this overview of the eruption and the variation in CVGHM’s volcanic hazard status: “On 14 September 2013, a new eruptive phase began. By mid-October the volcano was degassing almost daily with small phreatic eruptions. Seismic and visual activity continued to build into November. After nine powerful explosions in a 24 hour period, the Centre for Volcanology and Geological Hazard Mitigation (CVGHM) raised the Alert level to Level IV on 24 November 2013, the highest volcano rating. The status was decreased to Alert Level III on 8 April 2014.”

During this reporting interval, lava flows advanced in the sector S- SE from the summit (figure 20). In accord with that lobe or tongue of lava, incandescent zones were at various times noted in different parts of the flows. As reported by CVGHM, avalanches from the front of the advancing lava flows occurred often. Scientists associated this process with a distinct seismic signal called an avalanche earthquake. CVGHM repeatedly warned residents that the lava flows and their associated avalanches could threaten areas to the S and SE within 5 km of the summit. Measurements of the length of this flow are included in the table at the bottom of this report. A previous map with clearer labels of the earlier flows appears as figure 16 in BGVN 39:01.

Figure 20. Annotated photo showing the S-SE flank of Sinabung covered by an advancing lava flow (often referred to as lava tongue, ‘lidah lava’ in Indonesian). On 6 September 2014, the day of this photo, the lava flow was reported as measuring 2.915 km long from distal end to the vent area at or adjacent the summit lava dome. Although the upper slopes on the E (right) side are too cloudy to see, CVGHM had recorded the locations of the various dated flow margins there. Note the area on the upper flanks where some lava branched off the main lobe to create a series of small finger-shaped areas trending more to the W. Courtesy of CVGHM.

Seismicity at Sinabung included avalanche earthquakes, low-frequency earthquakes, tectonic earthquakes, volcanic earthquakes and ongoing tremor. Totals and measured averages of these seismic events are included when available (see table at bottom). CVGHM reported that the dominating seismic signals, avalanche earthquakes and intervals of constant tremor, were associated with the instability of the growing lava dome and lava flows.

During this reporting interval, numerous eruptions took place, often generating ash plumes and in some cases pyroclastic flow. During the eruptions, some ash plumes were detected by satellite imagery. Ground-based observations were also important. For example, CVGHM often detected Sinabung eruptions, PFs, and plumes via webcam. Darwin VAAC also benefited from the CVGHM webcam data in several of their VAAs. The VAAC has also begun to use social media to both dispense and retrieve operationally relevant information (Darwin VAAC, 2015). This has aided VAAC forecaster’s understanding of, for example, whether residents have noticed ashfall during times when ash is not discernable due to meteorological clouds (Darwin VAAC, 2015).

During May and October 2014, PFs had runout distances up to 4.5 km and ash plumes rose up to 5.2 km altitude. White or slightly discolored plumes were the most common type reported by CVGHM. These plumes sometimes rose to as high as on the order of 1 km over the summit.

Figure 21 is a map of Sinabung and towns surrounding the volcano.

Figure 21. Relief map of Sinabung volcano and surrounding towns, some of which are named in reporting. The base map was made prior to the current eruption and the lava tongue descending the S-SE flank is not shown. For scale, the distance is ~3 km from the summit area N to the closest (S) margin of Kawar lake. Map found online at Pixshark.com and edited by Bulletin editors.

 

Photographs. The following are photos documenting events at Sinabung during this reporting interval. Ancillary information pertaining to each photo can be found in a table at the bottom of this report.

Figure 22. Photo of a pyroclastic flow (PF) descending Sinabung on 14 August 2014. Two PFs occurred that day, at 0728 UTC and 0750 UTC. The time that this photo was captured is unknown. Photographer unknown; photo posted on Facebook by CVGHM and taken from the 13-19 August 2014 Darwin VAAC weekly activity report.
Figure 23. A pyroclastic flow (PF) captured at 0940 UTC on 2 September 2014. This PF travelled 1.5 km to the SE. Taken from the 27 August-2 September 2014 Darwin VAAC weekly activity report.
Figure 24. Sinabung in a low-light photo allegedly taken at 1444 UTC on 7 September 2014, which would make it about 46 minutes after Darwin VAAC reported an eruption. The ash plume rose 2 km above the summit and blew S. A rivulet of red glowing material descends an area of the flank. Bulletin editors interpret the rivulet as a lava flow (or possibly a glowing avalanche or both) traveling down the lava tongue on the S-SE flank. Copyrighted photo taken by Endro Lewa, posted on Facebook by CVGHM, and taken from the 3-9 September 2014 Darwin VAAC weekly activity report.
Figure 25. Eruption at Sinabung on 8 October 2014. This time and the location of this photo were unstated. Photo by the news agency AFP and taken from the 8-14 October 2014 Darwin VAAC weekly activity report.
Figure 26. (A) Ground-based photo of a Sinabung eruption column looking approximately NE on 19 October 2014. Photo was captured at 0731 UTC. The eruption column is obscured by weather clouds but is visible again above them in a small area. Photo was taken by Ricky Febriand, posted on Facebook by CVGHM, and taken from the 15-21 October 2014 Darwin VAAC weekly activity report. B. Aerial photo of Sinabung’s eruption column on 20 October 2014. Photo was captured at 0736 UTC. Height of eruption column and position photo was taken are unknown. Photo taken by Ricky Febriand, posted on Facebook by CVGHM and taken from the 15-21 October 2014 Darwin VAAC weekly activity report.

 

Data compilation. Table 4 summarizes activity at Sinabung from May-October 2014. Data sources include reporting by CVGHM (often the original source), the Darwin VAAC (their Volcanic Ash Advisories (VAAs), Weekly Activity Reports; and other reports), the Indonesian National Agency for Disaster Management (Badan Nacional Penanggulangan Bencana-BNPB), occasional news articles; and the Smithsonian-USGS Weekly Volcanic Activity Reports.

Table 4. A synthesis of Sinabung’s reported activity from May-October 2014. The bulk of this table came from CVGHM and Darwin VAAC reporting unless otherwise stated. Dates and times are in some cases ambiguous as to local time (LT) or UTC (LT = UTC +7 h). Abbreviations: pyroclastic flow, PF; Aviation Color Code, ACC; earthquake(s), EQ(s); maximum amplitude, max. amp.; and altitude, alt.

Week Remarks
30 Apr-20 May ACC: Orange
21-31 May

ACC: Orange

22nd: At 1132 UTC, Darwin VAAC noted a suspicious, possibly ash bearing cloud around Sinabung in a MTSAT-2 IR image. In retrospective analysis, Darwin VAAC concluded the cloud was the beginning of a cumulonimbus (Cb) cloud forming due to atmospheric instability in the area (unrelated to the eruption). For more information, see text and the 21-27 May 2014 issue of the Darwin Weekly Activity Report.

26th: Ash plume observed at 0132 UTC on MTSAT-2 satellite imagery. Plume extended 28 km SE at 3.4 km alt. Plume observed via webcam. Similar length ash plume again observed by satellite at 0432 UTC on 27th. VAA ended after plume no longer visible.

1-17 June

Lava flow associated with dome growth. S and SE flank lava avalanches. Columns of white plumes rose 100-400 m over crater. Seismicity dominated by avalanche EQs and tremor, both associated with instability of dome and lava flows. 13th: Lava flow: ~2.796 km long.

18-28 June

Visual monitoring from ~10 km ESE from summit (Post PGA Sinabung located in Ndokum Siroga village) confirmed ongoing dome growth and glowing areas of the lava flow. Avalanches from the flow front seen.

18-24th: Seismicity dominated by avalanche signals; minor deformation.

29 June

CVMGH reported an eruption with a 4 km alt. ash plume. PF flows travelled 4.5 km SE. Ashfall noted in settlements of Sigarang-Garang and Sukanalu (figure 21). Earthquakes reached high (105 mm) amplitude for 64 minutes. Dome growth continued. A Xinhua news report from 29 June 2014, noted a reporter’s telephone interview with a CVGHM authority; the basis for the article’s claim of up to 14,382 people still evacuated.

30 Jun-15 Jul

8-14th: Real-time Seismic Amplitude Measurement (RSAM) values from 8-15th remained steady. SO2 flux: 1,252 metric tons/day. Dome growth and lava flows continued.

8th: Thick white plume 100-200 m above summit. 38 avalanche EQs (max. amp. 2-70 mm).

9th: Thick bluish plume to 100 m above summit. 54 avalanche EQs; continuous tremor (max. amp. 2-53 mm).

10th: PF travelled up to 3 km S. Plumes of blue and brown color rose 200-2000 m above summit. 52 avalanche EQs and continuous tremor (max. amp. 2-53 mm.).

11th: Thick white plume 300-1000 m above summit. 59 avalanche EQs; continuous tremor (max. amp. 2-52 mm).

12th: Eruption at 2305; a PF moved ~4 km E. Ashfall at several places around Karo district. Maximum height of eruption column indeterminate. 88 avalanche EQs; 2 deep volcanic (VA) EQs. Continuous tremor (max. amp. 2-66 mm). No further evacuations reported.

13th: Thick white plume to 400 m over summit. 92 avalanche EQs; 1 deep volcanic (VA) EQ. Continuous tremor (max. amp. 2-45 mm).

14th: Lava flow: 2.824 km long. Thick white to bluish plume to 200 m above summit. 83 avalanche EQs; 3 deep volcanic (VA) EQs; continuous tremor (max. amp. 2-62 mm). 15th (until 0600LT): 34 avalanche EQs; continuous tremor (max. amp. 2-42 mm).

16-29 Jul 23rd: Molten lava captured in photo posted by CVGHM at 2207 on 22 July 2014 UTC. No ash identified on satellite imagery. No Volcanic Ash Advisories (VAAs) issued.
23-29 Jul ACC: Orange
13-19 Aug

ACC: Orange

13th: 94 avalanche EQs; 2 deep volcanic EQs; 2 deep tectonic EQs; and continuous tremor. Lava ~1000-1500 m from summit moving SE.

14th: PFs at 0728UTC and 0750UTC (figure 22). PFs travelled 1-1.5 km. White plumes rose 300-1000 m above the summit. 102 avalanche EQs; 3 deep volcanic EQs; and continuous tremor. Lava flow: ~2.904 km long

20-26 Aug

ACC: Orange

20-23th: White plumes rose 100-300 m over crater. Continuous tremor. Avalanche EQs reported on 20-21 and 23 Aug.

22th: PFs travelled 1.5 km to SE. 3 deep volcanic EQs recorded.

23th: 3 southerly moving PFs observed. (1) 0356 UTC, and travelling 2 km; (2) 1140 UTC, and travelling 2 km; (3) 0409 UTC and travelled 1.5 km.

27 Aug-2 Sept

ACC: Orange

29th: PF travelled 1.5 km to SE. Time of PF is unknown.

2th: PF at 0940 UTC travelled a distance of 1.5 km SE (figure 23)

3-9 Sept

ACC: Orange

5-11th: White plumes, appeared bluish on some days, rose 50-500 m over crater. Avalanche EQs (average of 96 events/day), low frequency EQs (average of 75 events/day), deep tectonic EQs, and deep volcanic EQs often recorded. Avalanches, travelling various distances observed moving SE and S.

6th: Lava flow: 2.915 km long (figure 20).

7th: Eruption at 1358 UTC that lasted 19 minutes. Plume rose 2 km above summit and ash from plume blown S (figure 24). Eruption’s PFs travelled max distances of 2 km to SE. 1 eruption earthquake noted.

10-16 Sept

10-16th: RSAM stable.

12-16th: White plumes rose 100-1000 m over crater. On occasions, the plumes had a bluish tint.

12th: Ash plume on webcam moving E/NE at 0140 UTC. Plume not identifiable on satellite imagery due to overlying clouds. Plume height of 3.7 km alt. (based on model data). Advisory terminated on UTC 13th at 0732 after satellite imagery indicated ash had dissipated.

15th: PF flow travelled 2.5 km to SE.

17-23 Sept

ACC: Orange

12-20th: Average total of avalanche EQs was 110 events/day, average for volcanic EQs was 1 event/day, average for low frequency EQs was 75 events/day and tremor was continuously recorded.

17-20th: White (sometimes bluish) plumes rose 100-200 m; RSAM stable. 18th: PFs reached 2 km to S.

24-30 Sept

ACC: Orange

24th: Eruption at 1343 emitted hot ash and gravel. Eruption lasted ~15 minutes and a PF descended ~2 km from summit. Eruption column height could not be determined. 4,700 residents remain in evacuation centers.

30th: Eruption at 1720 sent volcanic ash 2 km above the summit. A PF travelled 3.5 km from summit; PF’s direction was unstated. Recent eruptions covered settlements and agricultural lands around Sinabung with ash. News sources noted that farmers harvested their crops early to reduce losses.

1-7 Oct

5th: Four eruptions took place. (1) 0146: volcanic ash sent 2 km over crater and a PF moved max distance of 4.5 km S; (2) 0638: PFs travelled 2.5 km S; (3) 0736: PFs travelled 3 km S; and (4) 0753: eruption column with ash rose 3 km and PFs travelled 4.5 km S. No additional refugees were reported. Two other eruptions that caused PFs were reported at 0900 and 1200.

6th: Low-level eruption observed on webcam starting at 0120 UTC. Eruption plume moved E and a PF also seen moving below the summit.

7th: Volcanic ash at 5.2 km alt. moving S. Ash not identifiable in satellite imagery.

8-14 Oct

ACC: Orange

8th: At 0543 UTC, an initial VAA issued for an in-progress eruption. Eruption first noted through webcam, but no ash was seen in satellite imagery. Eruption produced a 4.9 km eruption column and a PF (both were observed by webcam at 0543 UTC) (figure 25). Another eruption observed at 2336 UTC by webcam.

9th: A low-level plume moving NE seen in satellite imagery at 0332 UTC. According to a 0531 UTC VAA, several eruptions were observed over the last 6 hours via webcam. Darwin VAAC weekly report noted that eruption from 8th reached the provincial capital Medan and disrupted flights on the 9th.

10th: Eruption was observed via webcam at 0200 UTC and through satellite imagery at 0132 UTC. In the imagery from 0132 UTC, an eruption plume extended 30 NM NE. Volcanic ash was noted at 0335 UTC in satellite imagery and was last seen at 0632 UTC extending 30 NM NE.

11th: Webcam captured a 3 km ash plume drifting SW.

12th: Volcanic ash on webcam at 0030 UTC to SE at 3.1 km alt. Volcanic ash was again observed at 0600 UTC via webcam.

14th: Ash plume recorded by webcam rising 4 km and moving SW.

15-21 Oct

ACC: Red

15th: At 0036 UTC, an eruption took place that sent ash 500 m over crater and a PF 2.5 km (direction unstated). At 0200 UTC, Sinabung was observed on webcam to 4.3 km alt. Eruption column moved N. Continuous small eruptions seen via webcam, during daylight hours.

17th: Ash rose to ~ 3.7 km alt. In photos taken by a pilot, ash seen extending ~15 mi to W of Sinabung. On ground, PF extended 3.5 km and ash was thrown up 2.5 km, according to a picture taken at 0409 UTC.

19-20th: Eruption columns seen via both ground-based and aerial images (figure 26)

22-28 Oct

ACC: Orange

23th: Eruption observed via webcam. Eruption column rose to 4.3 km alt. and extended 10 NM to N at 0400 UTC.

25th: Eruption at 0249 UTC seen via webcam. Volcanic ash at 4.6 km alt. identifiable through satellite images from 0332 UTC. Plume extended 15 NM to W-NW. Eruptions also seen via webcam at 1000 UTC and 2312 UTC. In a 2331 UTC VAA, ash plume reported at 3 km and drifting E based on webcam.

26th: Activity reported as high. PFs travelled 3.5 km S on two occasions and an ash plume rose 2 km over crater. Lava moved distances of 700-1000 m from summit.

27th: Eruption at 1013 UTC seen via webcam. BNPB reported ~3,000 people remained in evacuation shelters.

29-30 Oct ACC: Orange

 

References. Associated Press, 2014, Volcano in Western Indonesia erupts again, accessed on 28 September 2014, (URL: http://abcnews.go.com/International/wireStory/volcano-western-indonesia-erupts-25720623 )

Darwin VAAC, (6 August) 2014, VAAC Darwin Management Report [discussing 1 July 2013 to the 30 June 2014], International Civil Aviation Organization (ICAO); Eighteenth Meeting of the Meteorology Sub-Group (Met Sg/18) Of Apanpirg; ICAO Regional Sub-Office, Beijing, China; 18–21 August 2014 [Agenda Item 7.4: Research, development and implementation issues in the MET field, [7.4] Advisories and warnings, MET SG/18 - IP/17; Agenda Item 7.4; 6 August 2014; (Presented by Australia)]; 5 pp. (URL: http://www.icao.int/APAC/Meetings/2014 METSG18/IP17_AUS AI.7.4 - VAAC Darwin Management.pdf )

Darwin VAAC, (18 February) 2015, Darwin VAAC Management Report [discussing 1 July 2014-31 January 2015], International Civil Aviation Organization (ICAO), Fifth Meeting of Meteorological Hazards Task Force (MET/H TF/5), Seoul, Republic of Korea, 18 March 2015 [Thirteenth Meeting of the Asia/Pacific Regional Opmet Bulletin Exchange Working Group (Robex Wg/13), ROBEX WG/13 & MET/H TF/5 – WP/C6; Agenda Item (conjoint session) 2 (Presented by Australia)] (URL: http://www.icao.int/APAC/Meetings/2015 ROBEXWG13/WP-C6 - AI.2 - AUS - Darwin VAAC Management Report.pdf )

Indonesian National Agency for Disaster Management (Badan Nacional Penanggulangan Bencana-BNPB), 2014, Four time Sinabung, Normal Community Activity, accessed on 6 October 2014, (URL: http://bnpb.go.id/berita/2211/empat-kali-sinabung-meletus-masyarakat-beraktivitas-normal)

The Jakarta Post/Asia News Network, 2014, Mount Sinabung erupts again, accessed on 6 October 2014, (URL: http://news.asiaone.com/news/asia/mount-sinabung-erupts-again)

Okezone.com, 2014, accessed on 28 September 2014, (URL: http://news.okezone.com/read/2014/10/01/340/1046715/hujan-abu-gunung-sinabung-guyur-karo-petani-menderita )

Pixshark.com, accessed on 7 April 2015 (URL: http://pixshark.com/peta-gunung-sinabung.htm)

World Organizations of Volcano Observatories (WOVO), Aviation Colour Codes, accessed on 8 April 2015, (URL: http://www.wovo.org/aviation-colour-codes.html)

Xinhua News Agency, 2014, 2nd LD Writethru: Mount Sinabung in Indonesia erupts, triggering massive evacuation, accessed on 29 June 2014, (URL: http://www.globalpost.com/article/6190943/2014/06/29/2nd-ld-writethru-mount-sinabung-indonesia-erupts-triggering-massive)

Xinhua News Agency, 2014, Mount Sinabung erupts in Sumatra, Indonesia, accessed on 28 September 2014, (URL: http://english.cntv.cn/2014/09/24/ARTI1411549583755731.shtml).

Geologic Background. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical, 2460-m-high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Information Contacts: Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) (also known as Pusat Vulkanologi dan Mitigasi Bencana Geologi-PVMBG), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Indonesian National Agency for Disaster Management (Badan Nacional Penanggulangan Bencana-BNPB), Gedung Graha 55 Jl. Tanah Abang II No. 57, 10120, Jakarta Pusat (URL: http://www.bnpb.go.id/); and 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/advisories.shtml ).

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 Atmospheric Effects


The enormous aerosol cloud from the March-April 1982 eruption of Mexico's El Chichón persisted for years in the stratosphere, and led to the Atmospheric Effects section becoming a regular feature of the Bulletin. Descriptions of the initial dispersal of major eruption clouds remain with the individual eruption reports, but observations of long-term stratospheric aerosol loading will be found in this section.

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 Special Announcements


Special announcements of various kinds and obituaries.

View Special Announcements Reports

 Additional Reports


Reports are sometimes published that are not related to a Holocene volcano. These might include observations of a Pleistocene volcano, earthquake swarms, or floating pumice. Reports are also sometimes published in which the source of the activity is unknown or the report is determined to be false. All of these types of additional reports are listed below by subregion and subject.

Turkey


False Report of Sea of Marmara Eruption


Africa (northeastern) and Red Sea


False Report of Somalia Eruption


Africa (eastern)


False Report of Elgon Eruption


Kermadec Islands


Floating Pumice (Kermadec Islands)

1986 Submarine Explosion


Tonga Islands


Floating Pumice (Tonga)


Fiji Islands


Floating Pumice (Fiji)


New Britain


Likuranga


Andaman Islands


False Report of Andaman Islands Eruptions


Sangihe Islands


1968 Northern Celebes Earthquake

Kawio Barat


Mindanao


False Report of Mount Pinokis Eruption


Southeast Asia


Pumice Raft (South China Sea)

Land Subsidence near Ham Rong


Ryukyu Islands and Kyushu


Pumice Rafts (Ryukyu Islands)


Izu, Volcano, and Mariana Islands


Mikura Seamount

Acoustic Signals in 1996 from Unknown Source

Acoustic Signals in 1999-2000 from Unknown Source


Kuril Islands


Possible 1988 Eruption Plume


Mongolia


Har-Togoo


Aleutian Islands


Possible 1986 Eruption Plume


Mexico


False Report of New Volcano


Nicaragua


Apoyo


Colombia


La Lorenza Mud Volcano


Ecuador


Altar


Pacific Ocean (Chilean Islands)


False Report of Submarine Volcanism


Central Chile and Argentina


Estero de Parraguirre


West Indies


Mid-Cayman Spreading Center


Atlantic Ocean (northern)


Northern Reykjanes Ridge


Azores


Azores-Gibraltar Fracture Zone


Antarctica and South Sandwich Islands


Jun Jaegyu

East Scotia Ridge



 Special Announcements


Special Announcement Reports