High-level eruption at Marapi volcano, ash to 15 km (50 000 feet) a.s.l., Indonesia

A high-level eruption started at Indonesia’s Marapi volcano at 08:00 UTC on December 3, 2023. The Aviation Color Code was raised to Red.

According to the Darwin VAAC, volcanic ash was clearly identifiable on satellite, rising up to 15 km (50 000 feet) above sea level by 08:40 UTC, drifting WSW.

The eruption was accompanied by a pyroclastic flow on the volcano’s northern slope, with a sliding distance of 3 km (1.8 miles).

Dozens of hikers were stranded on the slopes of the volcano as it began its sudden and explosive eruption.

Indonesian rescuers have discovered the bodies of 11 climbers by Monday morning, December 4. Despite the challenging conditions, three individuals were found alive on the volcano, while the search continues for at least 12 climbers, with another estimate suggesting as many as 22 might still be missing.

Jodi Haryawan, a spokesperson for the local rescue agency, informed Agence France-Presse that the rescue operations have been intermittently disrupted by ongoing eruptions. However, the teams have persisted in their efforts. “Once it was safer they continued the search. So the search was not halted,” Haryawan stated, emphasizing the dedication and risks undertaken by the rescue team.

Earlier on Monday, 49 climbers were successfully evacuated from the area, with many receiving treatment for burns. Abdul Malik, the head of the Padang Search and Rescue Agency, provided an update on Sunday: “There are 26 people who have not been evacuated, we have found 14 of them, three were found alive and 11 were found dead.”

Malik also reported that there were a total of 75 hikers on the mountain since Saturday.

This eruption was recorded on a seismograph with a maximum amplitude of 30 mm and a duration of 4 minutes 41 seconds, PVMBG said, adding that it was not preceded by a significant increase in volcanic earthquakes.

“Deep Volcanic Earthquakes (VA) were only recorded 3 times between November 16 and December 2, 2023. The deformation equipment (tiltmeter) at the peak station showed a horizontal pattern on the radial axis and slight inflation on the tangential axis. This shows that the eruption process is taking place quickly and the pressure center is only at a shallow depth (around the peak).”

As of December 3 at 11:00 UTC, Mount Marapi’s activity level remains at Level II (Alert) based on observations and data analysis. Precautions and recommendations include prohibiting activities and approaching within a 3 km (1.8 miles) radius of the crater/peak for residents and tourists, encouraging people to stay calm and not be influenced by eruption rumors, advising the use of masks when venturing outside to mitigate the health impact of volcanic ash if ashfall occurs, ensuring clean water availability, and clearing roofs of houses from thick volcanic ash to prevent collapse.

The last eruption at Marapi volcano occurred in March 2023. During that incident, as reported by the PVMBG (Center for Volcanology and Geological Hazard Mitigation), a white-and-gray ash plume rose approximately 400 m (1 300 feet) above the volcano’s summit and moved north and east. There were no emissions observed on other days between March 15 and 19, although visibility was affected by cloudy conditions. On March 20, white gas plumes were observed rising about 50 m (165 feet) above the summit. Throughout this period, the Alert Level was maintained at 2 on a 1-4 scale, and the public was advised to stay at least 3 km (1.8 miles) away from the crater.

Gunung Marapi, distinct from the more well-known Merapi volcano on Java, is Sumatra’s most active volcano. This massive stratovolcano complex towers 2 km (1.2 miles) above the Bukittinggi Plain in the Padang Highlands.

The broad summit of Marapi hosts multiple overlapping summit craters situated within the small 1.4-km (0.8 miles) wide Bancah caldera. These summit craters align along an east-northeast to west-southwest line, with volcanic activity progressively shifting westward.

Historically, Marapi has been notably active, with over 50 eruptions recorded since the late 18^th century. These eruptions have primarily been small to moderate in scale, involving explosive activity, and no lava flows beyond the summit craters have been documented in historical times.

References:

¹ VA Advisories for Marapi volcano – DARWIN VAAC – December 3, 2023

² Marapi – Geological summary – GVP

Teo Blašković

I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.

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