Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.
06/1980 (SEAN 05:06) Large incandescent tephra to 1.5 km away
09/1980 (SEAN 05:09) Explosions resume, then end
07/1989 (SEAN 14:07) Weak white gas emission
03/1995 (BGVN 20:03) Eruption at Bromo causes ashfall 20 km away; gas emissions
10/1995 (BGVN 20:10) Eruption from Bromo sends dark ash plume 700 m above the rim
11/2000 (BGVN 25:11) Sudden explosion 29 November; eruption continues as of 18 December
01/2001 (BGVN 26:01) Minor explosions, ash emissions, and tremor through 8 January 2001
05/2004 (BGVN 29:05) Mount Bromo's 8 June eruption killed two and ejected a 3-km-high ash plume
07/2004 (BGVN 29:07) Video of the 8 June eruption; minor ash plumes through 18 July
06/1980 (SEAN 05:06) Large incandescent tephra to 1.5 km away
Vapor emission from Bromo cone . . . began 2 June. Several days later, Bromo started to eject incandescent tephra. Glowing bombs 1 m in diameter fell as much as 400 m from the crater rim, while ash-laden vapor rose 600-800 m, accompanied by rumbling. Crowds of tourists approached to within 500 m of the vent during the first two weeks of the eruption.Activity intensified during the 3rd week, with explosions every few seconds to two minutes. By 21 June, some cauliflower-shaped ash clouds rose 900 m. VSI moved tourists away from the immediate vicinity of the eruption to the caldera rim, where a resort hotel is located ~4 km from Bromo.
By 24 June, explosive episodes, accompanied by loud detonations, had become more vigorous but less frequent, occurring at 4-5 minute intervals. Although about half of the ejecta fell back into the crater, 1-m-diameter bombs set bushes afire at the foot of Batok cone, 1.5 km away.
Information Contacts: A. Sudradjat, L. Pardyanto, and Suparban, VSI.
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09/1980 (SEAN 05:09) Explosions resume, then end
Activity at Bromo cone peaked on 20-21 June when 480 explosions were recorded during a 24-hour period. Ash-laden steam columns rose 1.2 km and bombs fell 1.5 km away, setting vegetation afire. Activity declined in late June and remained weak until mid-July. Frequent explosions resumed 15 July, when about 1,000 were recorded in 24 hours. Explosions remained frequent for more than a week, then declined steadily after 24 July to about one every 48 hours in August. Kompas newspaper reported a minor eruption on 9 September at 0825 and added that tourists were not being allowed to descend to the crater. However, by the end of September, activity had weakened sufficiently to allow tourists into the crater area.
Information Contacts: A. Sudradjat and L. Pardyanto, VSI; M. Krafft, Cernay; Kompas, Bandung.
Further Reference: Siswoyo, S., 1978, Report on seismic activity at Bromo and Lamongan (1977-78): Geological Survey of Indonesia, Bandung.
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07/1989 (SEAN 14:07) Weak white gas emission
Normal activity continued . . . in July, with weak white fumes rising 30-60 m above the summit. A total of 449 gas emission earthquakes were recorded.
Information Contacts: VSI.
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03/1995 (BGVN 20:03) Eruption at Bromo causes ashfall 20 km away; gas emissions
An ash eruption from the active vent on the N side of Bromo crater at 0600 on 3 March produced a dark gray plume that rose 100-200 m above the crater rim. The plume extended >20 km S and SE, causing ashfall (0.5-2 mm thick) that covered ~10 km2 of cultivated land in and around the area of Sukapura (~20 km away). No injuries were reported as a result of this activity. Continuous weak-to-moderate gas emissions lasted through the end of March. COSPEC measurements showed that the SO2 flux was 6 t/d on 8 March. SO2 emission gradually increased to a peak of 22.8 t/d on the 18th before dropping again on 19-20 March (figure 1). Measurements during 27-31 March were again higher, 15-21 t/d.
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Figure 1. SO2 values measured by COSPEC (dots) and daily number of gas-emission tremor events (solid line) at Bromo (Tengger Caldera), March 1995. Courtesy of VSI. |
Volcanic tremor events associated with the gas emissions (maximum amplitude 2-7 mm) were recorded continuously beginning on 9 March using PS-2 and Teledyne seismographs installed between 500 and 1,000 m from the active crater. The number of distinct earthquakes (maximum amplitude <6 mm) dropped suddenly on 21 March from >1,100 to ~400, and gradually decreased through the end of the month (figure 1). Three tectonic earthquakes were detected on 23 February, and one each on 24 and 28 February, and 28 March.
Information Contacts: W. Tjetjep, VSI.
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10/1995 (BGVN 20:10) Eruption from Bromo sends dark ash plume 700 m above the rim
On 9 September, dark gray emissions were observed reaching a height of 70 m above the rim of Bromo Crater. Volcanic tremor associated with the emission events (maximum amplitude of 1-3 mm) was recorded continuously beginning on 8 September, using a PS-2 seismograph installed 750 m from the active crater. After 10 September the plume was denser than during the March-May 1995 activity (20:03). An international Notice to Airmen (NOTAM) on the morning of 22 September reported an ash cloud with a top at ~3 km altitude and a SW drift. The height of the ash column gradually increased, peaking at 700 m (~3 km altitude) on 25 September (figure 2); during the emission, maximum tremor amplitude was 49 mm. A thick dark gray ash cloud caused ashfall in nearby villages, reported as far away as ~20 km E (around the area of Sukapura). The eruption vent, with a diameter of ~25 m, was located on the N part of the crater floor, similar to the last eruption. Ash eruptions were continuing at the end of October, but the activity was gradually decreasing. In October the maximum plume height was 200-450 m above the crater rim; the maximum tremor amplitude was 8-40 mm.
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Figure 2. Height of ash plume and maximum tremor amplitude at Bromo, Tengger Caldera, September-October 1995. Courtesy of VSI. |
Information Contacts: W. Tjetjep, VSI; BOM Darwin, Australia.
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11/2000 (BGVN 25:11) Sudden explosion 29 November; eruption continues as of 18 December
A minor explosion issued from Bromo, the youngest cone of the Tengger volcanic complex (figure 3), without warning on 29 November 2000. Activity leading up to the explosion was low, characterized by a white plume that rose ~50 m on a daily basis (figure 4). The seismograph for the area was in disrepair since 18 October, so no seismic data were available. The explosion initiated with dark ash rising 100-150 m. Ash ejection persisted, reached 600-700 m in height above the crater rim, and the plume drifted up to 40 km from Bromo, where ash was deposited in layers 1-3 cm thick. A volcanic ash advisory was issued to aviators due to a plume ~1.2 km above the summit. Pilots were encouraged to navigate around the plume in order to avoid a potentially dangerous encounter. Following the explosion, the Volcanological Survey of Indonesia (VSI) repaired and upgraded the seismograph on the volcano.
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Figure 3. Photograph of the active Bromo cone in the Tengger volcanic complex on 14 July 2000, prior to the recent eruption, from the floor of the Sand Sea Caldera. Typical steam emissions can be seen rising from the crater, which is approximately 700 m in diameter at the rim. Courtesy of Ed Venzke, SI. |
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Figure 4. Photograph looking into the steaming Bromo crater of the Tengger volcanic complex on 14 July 2000. The field of view in this photo, taken from the crater rim, is on the order of 150 m. Courtesy of Ed Venzke, SI. |
Ongoing explosions and continuous tremor accompanied the volcanic activity during 5-11 December. Explosion earthquakes had amplitudes of 4-30 mm, while tremor had amplitudes of 2-6 mm. As of 5 December, the ash ejection was dark gray-brown in color, and smelled strongly of sulfur. Ash plumes rose 150-900 m over the following week, and by 8 December, satellite imagery showed convective clouds in the vicinity, and volcanic ash advisories indicated that the ash cloud had drifted to ~6.8 km above and E of the summit. The hazard status for Bromo cone placed at 2 (on a 1-4 scale). Explosions and tremor activity were ongoing and increased during the week of 12-18 December. Small explosions sent gray-brown to dark gray ash 500-600 m above the crater rim. A sulfur odor continued to be smelled at the observatory on the caldera rim (figure 5). Amplitudes for explosion earthquakes and tremor earthquakes were 5-34 mm and 1-5 mm, respectively. The seismograph recorded an unprecedented 2,375 explosion earthquakes in addition to continuous tremor.
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Figure 5. Photograph of the Bromo-Tengger Volcano Observatory maintained by VSI. The observatory is located on the oustide of the caldera wall, with a small building for visual observations on the rim (to the right in this view). Courtesy of Ed Venzke, SI. |
Information Contact: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id; URL: http://www.vsi.esdm.go.id/); 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/).
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01/2001 (BGVN 26:01) Minor explosions, ash emissions, and tremor through 8 January 2001
Explosions from Bromo cone and unbroken tremor continued at Tengger Caldera since the previous report (BGVN 25:11). An average of 99 minor explosions daily during 19-25 December 2000 produced gray-brown ash that rose ~300-450 m above the cone's rim. The volcano's seismograph recorded 678 explosion earthquakes and tremor with amplitudes that ranged from 2 to 12 mm.
VSI reports resumed during 2-8 January 2001 when activity was purportedly lower. Small explosions sent gray-brown to dark ash 200 m above the crater, and about 29 events occurred per day. The seismograph registered 191 explosion earthquakes and continuous tremor with amplitudes of 2-10 mm. Tengger's hazard status remained at 2 (on a scale of 1-4), and no further VSI reports were issued. The Darwin Volcanic Ash Advisory Centre, however, issued an advisory to aviators on 15 January to warn them of an ash cloud up to an altitude of 3 km drifting toward the NE. The advisory also stated that ground-based observations indicated that irregular eruptions sent ash up to altitudes of 2,750 m, over 400 m above the Bromo cone. When the report was issued, ash was expected to spread E-NE at ~30 km/hour; heavy cloud-cover prevented the acquisition of satellite information concerning the eruption. No further ash advisories were released after 15 January.
Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id; URL: http://www.vsi.esdm.go.id/); 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/).
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05/2004 (BGVN 29:05) Mount Bromo's 8 June eruption killed two and ejected a 3-km-high ash plume
Reports of the Volcanological Survey of Indonesia (VSI) stated that Mount Bromo produced a phreatic eruption at 1526 on 8 June 2004. The eruption killed two people and injured several others. The Bromo cone is the youngest and most active volcano within the larger Tengger caldera complex. Bromo also resides within an inner caldera (Sandsea caldera).
The eruption, which vented at the crater, had a duration of ~20 minutes. Ash rose up to 3 km above the crater rim (figure 6) and was blown to the WNW and detected at the Mount (Gunung) Kelud observatory (~ 75 km away). Lapilli and ash spread out over a radius of ~ 300 m from the crater's center.
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Figure 6. Bromo's 8 June 2004 eruption as seen 2.2 km away, looking from the N. The photographer, K. Nishi, was in the seismic station and saw evidence of the eruption on the seismic system. He ran to the adjacent crater rim and took a series of shots. This one was taken 9 minutes after the eruption began. The prominent cone on the right is Batok. Courtesy of K. Nishi. |
Bromo was closed to the public until further notice. Its hazard status was set to the elevated state of 'Alert Level III' (on a scale with a maximum of IV). Search and rescue teams were advised to stay away from the volcano until declaration of safe approach.
John Seach reported that many buildings in the nearby towns of Malang and Probolinggo were covered by a light coating of ash 2 hours after the eruption. The neighboring towns of Lumajang and Pasuruan were also affected by the eruption.
From 0600 on 9 June to 0600 on 10 June, visual observations disclosed a thin white and slightly red cloud about 25-50 m above the crater, moving W. Seismic records were dominated by tremor with peak-to-peak amplitudes ranging from ~ 1-4 mm. Seismometers also registered 123 emission earthquakes and 15 type-A volcanic earthquakes.
During 1800 on 10 June through 0600 on 11 June, the activity of Bromo was dominated by 'smoke emissions' of low-to-medium intensity reaching heights of ~ 25-100 m. Shallow volcanic earthquakes increased, and continuous tremor occurred with a peak-to-peak amplitude of 6.0 mm. Four volcanic earthquakes were detected within about 8-15 minutes, followed by tremor for 18 minutes, after which came 8 volcanic earthquakes. Despite all of the tremor and earthquakes, however, no explosion followed. When the weather was clear, VSI scientists could see white, thick 'smoke' emissions and smelled sulfur.
At 0819 on 14 June 2004, there was an ash explosion, accompanied by a plume that rose to 100 m. Pre-explosion spectrometer measurements suggested SO2 fluxes of 200 tons/day. During 13-14 June the seismic record contained emission and tectonic earthquakes, as well as a half hour of continuous tremor with a peak-to-peak amplitude of 6.0 mm. Deformation measurement using electronic distance meters (EDM) and global positioning systems (GPS) implied deflations of about 2-6 mm and 2-15 mm, respectively.
By 0630 on 15 June 2004, activity at Bromo had generally decreased, and the Alert Level was reduced to Level II. During that day emissions of white thin smoke rose ~ 25-150 m above the summit and the seismograph recorded 24 emission earthquakes and 1 tectonic earthquake. Deformation measured by EDM and GPS implied respective deflations of 1.0-5.0 mm and 0.2-6.2 mm.
Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Directorate of Volcanology and Geological Hazard Mitigation, Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id; Email: dali@vsi.esdm.go.id/); Heri Retnowate, Reuters; Derwin Pereira, The Straits Times; John Seach, P.O. Box 842, Southport BC 4215, Queensland, Australia (URL: http://www.volcanolive.com; Email: john@volcanolive.com); 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/).
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07/2004 (BGVN 29:07) Video of the 8 June eruption; minor ash plumes through 18 July
Mount Bromo's 8 June 2004 eruption killed two visitors and injured five more (BGVN 29:05). This report mainly adds a few details for the events of 8 June and a video of the eruption plume. It also summarizes reports through 18 July, an interval characterized by mild ash-bearing eruptions (to 100 m high) without a repeat of the robust eruption seen on 8 June.
A 3-minute-long video clip of the eruption was shot by Kiyoshi Nishi, a volcano seismologist attached to the Indonesian Directorate of Volcanology and Geological Hazard Mitigation (DVGHM). (DVGHM was reorganized from the former Volcanological Survey of Indonesia). Nishi works for the Japan International Cooperation Agency, a Japanese government organization offering technical and grant assistance.
The video begins after a substantial plume had already developed. The plume continued to rise, and the main body of it appeared to ascend with only minor effects of wind, rising in a roughly vertical direction. Identifiable zones of distinct coloration appeared within the plume, in shades of brown, reddish-brown, gray, and white. The white-gray zone, which clearly erupted earlier, moved away from the viewer. Most of the footage shows the brown and red parts of the plume evolving. Subsidiary clouds several times began bulging out of the main plume's margins. The image is valuable because of the need to accurately assess ash plume heights and behavior such as the rise time of the plume top, colored zones, and subsidiary clouds, and the absolute plume heights with respect to time.
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Movie 1. Video showing the Bromo eruption of 8 June 2004, taken looking from the NE, at a spot in the vicinity of the seismic station and ~ 2.2 km away from the eruptive vent on Bromo. The video (34.7 MB, 3.0-minute long AVI) began at 15 hours, 25 minutes, and 45 seconds; it was shot with a Canon IXY Digital 30 camera in movie mode at 15 frames/second. The same video was also featured on the VSI website. The video begins in 'landscape' format and later shifts to 'portrait' format. Courtesy of Kyoshi Nishi, JICA Silver Expert. |
Seismicity during 9-14 June was marked by long periods of continuous tremor (maximum peak-to-peak amplitude 6.0 mm), shallow type-A and type-B volcanic earthquakes, intermittent tectonic earthquakes, and a high number of emission earthquakes (see table 1 and BGVN 29:05 for details). Reports around this time noted that distance meters (EDM) and global positioning system (GPS) receivers on Bromo recorded deformation that suggested deflation of the edifice. On 14 June, Bromo ejected another ash plume that rose 100 m above the summit.
Table 1. Weekly seismicity at Bromo as measured by the Volcanological Survey of Indonesia (VSI) seismograph. Courtesy of VSI.
Date Volcanic Volcanic Tremor Local Emission
Type A Type B Tectonic
07 Jun-13 Jun 26 15 continuous 0 387
14 Jun-20 Jun 0 0 0 0 376
21 Jun-27 Jun 15 0 3 3 163
28 Jun-04 Jul 1 0 2 0 104
05 Jul-11 Jul 2 0 2 3 116
12 Jul-18 Jul 2 0 3 0 79
Nearly two weeks after the 8 June eruption, no similarly substantial event had occurred. On 15 June, DVGHM decreased the Alert Level to II, or 'eruption imminent.' Reports covering 14 June-18 July noted a decrease in seismically detected volcanic emissions (table 2). The number of emission earthquakes decreased by ~ 50% after 20 June and dropped again the week of 12-18 July. Bromo's emissions continued to bear ash, and during 14-27 June a thick ash plume rose 25-100 m above the crater rim. In accord with the decline in seismically detected emissions, observers noted smaller (25-50 m high), thinner plumes during 28 June-18 July.
Other seismicity also decreased (table 2). Seismometers recorded 15 type-A earthquakes during 21-27 June, but this was a peak in the trend for 14 June-18 July, which was generally 1-2 per week. Seismometers recorded no type-B earthquakes at Bromo since the week of its phreatic eruption. Tremor, continuous during 7-13 June, dropped to 2-3 events/week. Local tectonic earthquakes were intermittent.
Information Contacts: Directorate of Volcanology and Geological Hazard Mitigation (DVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id; URL: http://www.vsi.esdm.go.id/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Kiyoshi Nishi, Japan International Cooperation Agency (JICA) (URL: http//www.jica.go.jp/).