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Report on Sinabung (Indonesia) — September 2018


Bulletin of the Global Volcanism Network, vol. 43, no. 9 (September 2018)
Managing Editor: Edward Venzke. Edited by Janine B. Krippner.

Sinabung (Indonesia) No significant ash plumes seen after 22 June 2018; minor ash in early July

Please cite this report as:

Global Volcanism Program, 2018. Report on Sinabung (Indonesia) (Krippner, J.B., and Venzke, E., eds.). Bulletin of the Global Volcanism Network, 43:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN201809-261080



3.17°N, 98.392°E; summit elev. 2460 m

All times are local (unless otherwise noted)

Sinabung volcano is located in the Karo regency of North Sumatra, Indonesia. The current eruptive episode commenced in late 2013, after phreatic activity in 2010, producing ash plumes, lava domes and flows, and pyroclastic flows that caused evacuation and relocation of nearby communities. This report covers activity from April through early July, and is based on information provided by MAGMA Indonesia, the Darwin Volcanic Ash Advisory Center (VAAC), the Center for Volcanology and Geological Hazard Mitigation (CVGHM, also known as PVMBG), satellite data, and field photographs. Sinabung has been on Alert Level IV, the highest hazard status, since 2 June 2015.

The eruption has built a pyroclastic flow and lava fan to the SE (figure 60). This activity continued into 2018, with the last significant ash plume reported on 22 June (table 8). However, minor ash emissions continued at least through 5 July 2018.

Figure (see Caption) Figure 60. Satellite images showing Sinabung before and after the eruption with the newly-developed fan of pyroclastic flow, volcanic ash, and lava flow deposits. Top: Landsat-8 true color satellite image (pan-sharpened) acquired on 7 June 2013 before the eruption began. Bottom: Sentinel-2 natural color satellite image acquired on 16 July 2018, after the eruption ended. Courtesy of Sentinel Hub Playground.

Table 8. Summary of ash plumes (altitude and drift direction) and pyroclastic flows at Sinabung, April-June 2018. The summit is at 2,460 m elevation. Data courtesy of Darwin VAAC reports, MAGMA Indonesia VAAC reports, and CVGHM volcanic activity reports.

Date Ash plume altitude (km) Ash plume drift direction Pyroclastic flows
06 Apr 2018 7.5 W, S 3.5 km
12 Apr 2018 2.7 WNW Yes
19 Apr 2018 5.5 ESE 1 km
19 May 2018 3.2 NW --
20 May 2018 5.0 WNW --
15 Jun 2018 3.0 ESE --
22 Jun 2018 3.5 SE --

An eruption on 6 April 2018 at 1607 local time produced an ash plume that reached about 7.5 km above the summit. The eruption also produced pyroclastic flows that traveled about 3.5 km from the summit down the SE slope (figure 61). The eruption resulted in the closure of a nearby airport and ashfall affected hundreds of hectares of agricultural land. Two more notable ash plumes were reported on 12 and 19 April, to altitudes of about 2.7 and 5.5 km, respectively. A pyroclastic flow was reported during the 12 April eruption. Smaller ash and gas emissions occurred through the month.

Figure (see Caption) Figure 61. Eruption of Sinabung on 6 April 2018 at 1600 local time that produced an ash plume that reached over 5 km above the summit, and pyroclastic flows that reached about 3.5 km down the SE flank. Courtesy of Agence France-Presse via Straits Times.

Two ash plumes were recorded on 19 and 20 May, rising to about 3.2 and 5 km altitude, respectively. Throughout June small diffuse gas-and-ash plumes continued (figures 62 and 63). The last activity reported by the agencies was on the 15 and 22 June, when ash plumes reached 3 and 3.5 km altitude (figure 64). Activity after 22 June was limited to seismicity and ash, gas, and steam plumes to several hundred meters above the summit (figure 65). Although an elevated thermal signature was detected in Sentinel-2 satellite data on 30 August 2018, there were no reports of renewed activity.

Figure (see Caption) Figure 62. View of the Sinabung summit vent area during ash venting on 20 June 2018. This view from the SW shows the perched remains of the lava dome and collapse scar. Photo courtesy of Brett Carr, Lamont-Doherty Earth Observatory.
Figure (see Caption) Figure 63. Relatively consistent ash venting at Sinabung on 20 June 2018. This view shows the pyroclastic flow fan and the 2014 lava flow in the lower center of the photo. Drone photo courtesy of Brett Carr, Lamont-Doherty Earth Observatory.
Figure (see Caption) Figure 64. Small ash plume rising from Sinabung at 2106 on 22 June 2018. The ash plume reached about 1 km above the crater. Courtesy of BNPB (color adjusted).
Figure (see Caption) Figure 65. Minor ash venting at Sinabung on 5 July 2018. Photo courtesy of Brett Carr, Lamont-Doherty Earth Observatory.

Geological Summary. 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 andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. 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: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as Indonesian Center for Volcanology and Geological Hazard Mitigation, CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/); Badan Nasional Penanggulangan Bencana (BNPB), National Disaster Management Agency, Graha BNPB - Jl. Scout Kav.38, East Jakarta 13120, Indonesia (URL: http://www.bnpb.go.id/, Twitter: https://twitter.com/BNPB_Indonesia ); MAGMA Indonesia, Kementerian Energi dan Sumber Daya Mineral (URL: https://magma.vsi.esdm.go.id/, Twitter: https://twitter.com/id_magma); 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/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Brett Carr, Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY (URL: https://www.ldeo.columbia.edu/user/bcarr); Agence France-Presse (URL: http://www.afp.com/); Straits Times (URL: https://www.straitstimes.com).