Dempo

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  • Indonesia
  • Indonesia
  • Stratovolcano(es)
  • 2009 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 4.03°S
  • 103.13°E

  • 3173 m
    10407 ft

  • 261230
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

18 March-24 March 2009

On 23 March, CVGHM lowered the Alert Level for Dempo from 2 to 1 (on a scale of 1-4) based on visual observations of the crater lake during 5-6 January and 2-4 March, and decreased seismicity since a phreatic eruption on 1 January. Visitors and residents were advised not to go within a 1-km radius of the summit.

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

Index of Weekly Reports


2009: March
2008: December
2006: September

Weekly Reports


18 March-24 March 2009

On 23 March, CVGHM lowered the Alert Level for Dempo from 2 to 1 (on a scale of 1-4) based on visual observations of the crater lake during 5-6 January and 2-4 March, and decreased seismicity since a phreatic eruption on 1 January. Visitors and residents were advised not to go within a 1-km radius of the summit.

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


31 December-6 January 2009

CVGHM reported that on 1 January, a phreatic eruption from Dempo resulted in a strong sulfur odor and "ash rain" that was noted as far as about 10 km from the summit. Fog prevented direct observations of the summit. The Alert Level was raised to 2 (on a scale from 1-4). Visitors and residents were advised not to go within a 2-km radius of the summit.

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


20 September-26 September 2006

Increased seismicity at Dempo resulted in an elevation of the hazard status to Alert Level 2.

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


Index of Monthly Reports

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

08/1999 (BGVN 24:08) Earthquakes 18-19 September increase alert status

01/2009 (BGVN 34:01) Sudden phreatic eruption on 1 January 2009

03/2009 (BGVN 34:03) Phreatic eruption in September 2006 sent mud 300 m


Contents of Monthly Reports

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

All times are local (= UTC + 7 hours)

08/1999 (BGVN 24:08) Earthquakes 18-19 September increase alert status

At 1810 on 18 September an earthquake was felt in an area around Dempo. The Volcanological Survey of Indonesia (VSI) reported its Modified Mercalli (MM) Intensity as MM IV. The following day three more earthquakes were felt: the first event took place at 0900 (MM II), the next at 1155 (MM I), and the last at 1800 (MM I). Recorded seismicity during these days indicated 30 events/day with amplitudes of 20-30 mm and arrival time differences (S-P) of 2-3 seconds on average. Volcanologists took this to mean that the earthquakes were local tectonic events. No visible signs of changed activity were apparent at the crater. The VSI took the precaution of increasing the condition of alert to Level II.

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

01/2009 (BGVN 34:01) Sudden phreatic eruption on 1 January 2009

According to a report by Indonesia's Center of Volcanology and Geological Hazard Mitigation (CVGHM), Dempo had a phreatic eruption on 1 January 2009. The event resulted in a strong sulfur odor and an ash (or cinder) rain that was noted as far as ~ 10 km from the summit. During 27 December 2008 to 1 January 2009, fog prevented direct observations of the summit; clouds over the summit area are a common occurrence. The one available photo of the eruption showed a whitish-colored plume rising perhaps a few kilometers over the summit.

On 1 January authorities raised the alert status from 1 (normal) to 2 (alert, "Waspada" in Indonesian), on a scale that ranges from 1-4. Visitors and residents were advised not to go within a 2-km radius of the summit. A 2 January report from CVGHM noted that both local volcanic and regional tectonic earthquakes were recorded during 27 December 2008 through 1 January 2009 (table 1).

Table 1. Highlights of Dempo seismicity recorded during 27 December 2008 to 1 January 2009. Courtesy of CVGHM.

    Date           Seismicity

    27 Dec 2008    One local volcanic (A-type), and two tectonic
    28 Dec 2008    One local volcanic (A-type), and one air blast event
    29 Dec 2008    One local volcanic, five air blasts, and two tectonic
    30 Dec 2008    One shallow local volcanic, one air blast, one low-frequency, and one tectonic
    31 Dec 2008    One local volcanic, one air blast, and two tectonic not at the volcano
    01 Jan 2009    One local volcanic related to the explosive eruption

As of early 2009, no thermal anomalies had been measured over Dempo by the MODVOLC infrared satellite system for at least the last 5 years. ASTER images from 2001-2007 show extensive cloud cover.

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

03/2009 (BGVN 34:03) Phreatic eruption in September 2006 sent mud 300 m

Our most recent report on Dempo (BGVN 34:01) discussed a phreatic eruption on 1 January 2009. This eruption prompted Indonesia's Center of Volcanology and Geological Hazard Mitigation (CVGHM) to raise the alert level from 1 (normal) to 2 (alert) on a scale of 1-4. A few months later, on 23 March 2009, the CVGHM lowered Dempo's Alert Level to 1, based on visual observations of the crater lake during 5-6 January and 2-4 March, and decreased seismicity since the 1 January phreatic eruption.

The name Dempo applies to both the larger complex and to a peak that sits adjacent to a neighboring peak called Marapi. The latter volcano name applies to several different volcanoes in Indonesia and is easily confused with the very prominent volcano Merapi (central Java). The Marapi cone in the Dempo complex contains a ~ 400 m diameter crater lake, the source of both the 2006 and 2009 eruptions.

The remainder of this report discusses the phreatic eruption that occurred in September 2006. This eruption had not been previously discussed in the Bulletin, and CVGHM reporting on the subject has recently come to our attention.

In the month before this eruption, teams from the CVGHM had visited several times. On 13 August 2006, a team prepared a map of Dempo and reported that the condition of the water in Marapi's crater lake was normal and clear or slightly blue in color, with no bubbling. On 4 September 2006, a team climbed to the peak of Dempo and reported that activity was normal other than some bubbling at the E edge of the crater lake.

2006 phreatic eruption. On 25 September 2006, a phreatic eruption occurred that expelled water from Marapi's crater lake and propelled mud onto the area around the peak up to a radius of 300 m.

On the next day, the inspector for Dempo, Mr. Mulyadi, accompanied by six friends, inspected the volcano and its lake. According to Mulyadi's team, the lake water was bubbling and had changed to a grayish color. Acrid sulfurosu emissions were accompanied by a hissing sound. The NW crater wall was covered by mud from the eruption. Many of the phreatic deposits around the crater lake were only about 0.5 cm thick, although in several other places they were thicker (figures 1-4). A visit on 4 October 2006 found the deposits not yet eroded, owing to a lack of rain since the eruption.

Figure 1. Photo of the plume resulting from Dempo's phreatic eruption on 25 September 2006. This is one of a set of multiple photos taken of a rising plume. Photo by Fredy, a local resident. Courtesy of CVGHM.
Figure 2. (top) Pre-eruption and (bottom) post-eruption scenes from the saddle between the cones of Dempo and Marapi looking upslope towards Marapi (which contains the source vent in a steep-sided crater not visible from this perspective). The shots were taken on 7 and 26 September 2009, respectively. Freshly deposited mud and evidence of ejected crater-lake water in the foreground (bottom) represents distal deposits from the 25 September eruption; note peson at right for scale. Large blocks were not from this eruption. Courtesy of the Dempo inspection team, CVGHM.
Figure 3. Pre- and post-eruption photos looking into Marapi crater at Dempo, taken on 7 (top) and 26 (bottom) September 2006. The lake is on the order of 400 m across. The bottom photo portrays the crater's mud-covered walls and sediment-covered lake. Comparison of both photos indicates that after the eruption the lake surface had dropped, consistent with discharge of water and mud. Camera look-direction unstated. Courtesy of the Dempo inspection team, CVGHM.
Figure 4. Post-eruption conditions on Dempo's Marapi cone seen from a point a few meters back from the crater rim. Widespread gray-to-brown mud covered the rim and upper crater, creating a desolate scene. The large angular blocks on the rim were placed there in previous events, not the 25 September 2009 eruption. Unstated direction; photographers shadow and gear for scale. Courtesy of the Dempo inspection team, CVGHM.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/).

Dempo is a prominent 3173-m-high stratovolcano that rises above the Pasumah Plain of SE Sumatra. The andesitic Dempo volcanic complex has two main peaks, Gunung Dempo and Gunung Marapi, constructed near the SE rim of a 3 x 5 km caldera breached to the north. The one called Dempo is slightly lower, with an elevation of 3049 m and lies at the SE end of the summit complex. The taller Marapi cone, with a summit elevation 3173 m, was constructed within a crater cutting the older Gunung Dempo edifice. Remnants of 7 craters are found at or near the summit of the complex, with volcanism migrating to the WNW with time. The large, 800 x 1100 m wide historically active summit crater cuts the NW side of Gunung Marapi (not to be confused with Marapi volcano 500 km to the NW in Sumatra) and contains a 400-m-wide lake located at the far NW end of the crater complex. Historical eruptions have been restricted to small-to-moderate explosive activity that produced ashfall near the volcano.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2009 Jan 1 2009 Jan 1 Confirmed 1 Historical Observations
2006 Sep 25 2006 Sep 25 Confirmed 1 Historical Observations
1994 Oct 1994 Oct Confirmed 1 Historical Observations
1974 Feb 26 1974 Oct 20 Confirmed 2 Historical Observations
1973 Jan 24 1973 Jan 25 Confirmed 2 Historical Observations
1964 Feb 14 1964 Feb 14 Confirmed 2 Historical Observations
1940 Jul Unknown Confirmed 2 Historical Observations
1939 Dec 19 1940 Feb 21 Confirmed 2 Historical Observations
1939 Jul 18 1939 Jul 30 Confirmed 2 Historical Observations
1936 Nov 26 1936 Nov 27 Confirmed 2 Historical Observations
1934 Jan 24 1934 Apr 25 Confirmed 2 Historical Observations
1926 Apr 22 1926 Apr 24 Confirmed 2 Historical Observations
1923 May 19 (?) 1923 May 19 (?) Confirmed 1 Historical Observations
1921 Apr 1921 Apr Confirmed 1 Historical Observations
1908 Feb 16 1908 Feb 17 Confirmed 2 Historical Observations
1905 Unknown Confirmed 0 Historical Observations
1900 Oct 26 1900 Oct 27 Confirmed 2 Historical Observations
1900 Jun 4 1900 Jun 4 Confirmed 2 Historical Observations
1895 Jul 2 1895 Sep 30 Confirmed 2 Historical Observations
1884 Jun 1884 Jul Confirmed 2 Historical Observations
1881 Dec 1881 Dec Confirmed 2 Historical Observations
1881 Feb 16 Unknown Confirmed 2 Historical Observations
1880 May Unknown Confirmed 2 Historical Observations
1879 May 18 Unknown Confirmed 2 Historical Observations
1853 Jan 1 Unknown Confirmed 2 Historical Observations
1839 (?) Unknown Confirmed 2 Historical Observations
1817 Dec 31 ± 365 days Unknown Confirmed 2 Historical Observations

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



Cones
Feature Name Feature Type Elevation Latitude Longitude
Marapi, Gunung Stratovolcano 3173 m 4° 2' 0" S 103° 8' 0" E
An atmospheric cloud rises above the summit of Dempo stratovolcano in SE Sumatra. Gunung Dempo here towers nearly 3 km above tea plantations below its eastern flank. Dempo is one of Sumatra's most active volcanoes, producing small-to-moderate explosive eruptions. Seven partially overlapping craters cut the summit; the youngest of these is partially filled by a crater lake.

Photo by Deddy Rochendi, 1981 (Volcanological Survey of Indonesia).
The youngest crater of Dempo volcano, at the WNW end of a series of six partially overlapping craters cutting the summit, contains a 400-m-wide crater lake that has been the source of frequent phreatic eruptions during historical time. A seventh smaller crater is located on the upper north flank. Dempo is one of Sumatra's most active volcanoes, frequently producing small-to-moderate explosive eruptions.

Photo by Ruska Hadian, 1989 (Volcanological Survey of Indonesia).
The crater wall of Kawah Merapi, the youngest and NW-most of the craters cutting the summit of Dempo volcano, is capped by thin lava flows; a crater lake is seen at the lower right in this view from the NE. Gunung Merapi, the high point of the summit region of Dempo volcano, occurs at the extreme left at the SE part of the crater rim.

Photo by Ruska Hadian, 1989 (Volcanological Survey of Indonesia).
The crater wall above the historically active crater lake of Kawah Merapi at the summit of Dempo volcano shows a series of alternating lava flows and pyroclastic deposits.

Photo by Ruska Hadian, 1989 (Volcanological Survey of Indonesia).
A scientist from the Volcanological Survey of Indonesia investigates rocks in the summit crater of Dempo volcano. The crater of Kawah Merapi on Dempo volcano truncates bedded pyroclastic material that is overlain by a series of light-colored lava flows.

Photo by R. Whandyo, 1992 (Volcanological Survey of Indonesia).
An aerial view from the north shows the summit crater of Dempo volcano at the upper left. The steep-walled crater contains a lake, out of sight in this view behind the NW crater rim. The crater lake has been the source of frequent phreatic eruptions during historical time.

Anonymous photo, 1991.
Gunung Dempo, one of the most active volcanoes of Sumatra, has a conical profile when viewed from the village of Pageralam below the eastern flank of the volcano. The summit contains nested craters on its NW side.

Photo by Sumarma Hamidi, 1972 (Volcanological Survey of Indonesia).

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

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

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

Volcano Types

Stratovolcano(es)
Caldera

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
124
9,613
96,058
2,307,584

Affiliated Databases

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