Increased activity at Sorikmarapi volcano, Indonesia

Sorikmarapi on September 10, 2022

Indonesian PVMBG is reporting increased activity under the Sorikmarapi stratovolcano, North Sumatra, Indonesia. The last eruption at this volcano took place in 1986 (VEI 1).

The activity at the volcano has fluctuated since January 2022, and the current activity is at Level 1 (Normal), PVMBG reports.1

There has been an increase in the number of volcano-tectonic earthquakes on September 29, 2022, with as many as 146 events, but there was no visual increase in the activity of the volcano. 

This shows that there is an increase in pressure that can come from hydrothermal activity and magma activity in the body of the volcano but still does not show an increase at the surface.

Sorikmarapi on September 10, 2022
Sorikmarapi on September 10, 2022. Credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers
sorikmarapi september 29 2022

It is necessary to watch out for potential hazards in the form of phreatic eruptions, namely eruptions related to hydrothermal activity. If a phreatic eruption occurs, it can be accompanied by ash rain, mudflow, and the ejection of material around the crater, PVMBG volcanologists said.

In the Level I (Normal) activity level, residents living around Sorikmarapi volcano and visitors/tourists are not allowed to approach the crater at close range. If an increase in the intensity/thickness of the crater smoke is observed and/ or if there is a strong smell of gas, people should immediately move away/leave the area around the crater to avoid the potential danger of exposure to toxic gases or phreatic eruptions.

Sorikmarapi hazard map - September 30, 2022. Credit: PVMBG
Sorikmarapi hazard map – September 30, 2022. Credit: PVMBG

The last known eruption at this volcano lasted from July 5 to 14, 1986 (VEI 1). An unconfirmed eruption was noted on May 5, 1996.

This volcano has a history of VEI 2 eruptions since 1829.

Geological summary

Sorikmarapi is a forested stratovolcano with a 600 m (X feet) wide summit crater containing a lake and substantial sulfur deposits.

A smaller parasitic crater (Danau Merah) on the upper SE flank also contains a crater lake; these two craters and a series of smaller explosion pits occur along a NW-SE line.

Several solfatara fields are located on the E flank.

Phreatic eruptions have occurred from summit and flank vents during the 19th and 20th centuries.2


1 G. Sorik Marapi – PVMBG press release – September 30, 2022

2 Sorikmarapi – Geological summary – GVP

Featured image: Sorikmarapi on September 10, 2022. Credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers


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