Potential tsunami risk after major eruption at Ruang volcano, Indonesia

Indonesia’s Ruang volcano in North Sulawesi experienced several violent eruptions on April 16 and 17, 2024, forcing authorities to raise the Alert Level to 4 of 4 and warn nearby residents there is a potential of a tsunami if parts of the volcano collapse into the sea, similarly to what happened in 1871. The last eruptive episode at this volcano was in September 2002 (VEI 4).

A series of powerful eruptions took place at Ruang volcano starting at 17:08 UTC on April 16 and continuing into April 17, with volcanic ash rising to 16.7 km (55 000 feet) above sea level.

The eruption forced local authorities to evacuate the entire island of Raung (population ~800) as a preventive measure and by April 17, the number of people to evacuate rose to nearly 12 000.

The Aviation Color Code was raised to Red. The Alert Level to 3 of 4 on April 16 and then to 4 of 4 at 12:00 UTC on April 17.

The airport in Manado, located about 100 km (62 miles) SSE of the volcano, was temporarily closed, while Air Asia canceled flights with nine airports in East Malaysia and Brunei. Additionally, falling rocks and ash damaged homes on Raung Island and forced a nearby hospital to evacuate.

“The potential for further eruption is still high, so we need to remain alert,” PVMBG official Heruningtyas Desi Purnamasari said on April 18.

Authorities are urging communities around Ruang volcano and visitors/tourists to remain alert and stay away at least 6 km (3.7 miles) from the crater:

People who live in the P. Tagulandang area within a 6 km (3.7 miles) radius must be immediately evacuated to a safe place outside the 6 km radius, PVMBG volcanologists said on April 17.

People living on Tagulandang Island, especially those who live near the coast, should also be aware of the potential for ejections of incandescent rocks, pyroclastic flows, and tsunamis caused by volcanic bodies collapsing into the sea.

During the 1871 eruption of the volcano (VEI 2), a part of the volcano collapsed into the sea, triggering a 25 m (82 feet) high tsunami that flooded many villages and killed around 400 people.

“Last night people evacuated on their own but without direction due to the volcano’s eruption and materials in the form of small rocks that fell, so the people scattered to find evacuation routes,” said Jandry Paendong, an official from the local search and rescue agency, in a statement on today.

Paendong called for more boats and equipment so his team could carry out evacuation for people on the coast or near the coast facing the volcano.

The last eruptive episode at Ruang volcano took place from September 25 to 29, 2002 (VEI 4).

This is the southernmost volcano in the Sangihe Island arc, north of Sulawesi Island; it is not the better-known Raung volcano on Java. The 4 x 5 km (2.5 x 3.1 miles) island volcano is across a narrow strait SW of the larger Tagulandang Island.

Its summit contains a crater partially filled by a lava dome initially emplaced in 1904. Explosive eruptions recorded since 1808 have often been accompanied by lava dome formation and pyroclastic flows that have damaged inhabited areas.

References:

¹ Massive eruption at Ruang volcano forces mass evacuation, ash to 16.7 km (55 000 feet) a.s.l., Indonesia – The Watchers – April 17, 2024

² Penyampaian Kenaikan Tingkat Aktivitas G. Ruang Dari Level III (Siaga) Menjadi Level IV (AWAS) – PVMBG – April 17, 2024

³ Ruang volcano geological summary – GVP

Featured image credit: JMA/Himawari-9, RAMMB/CIRA, The Watchers. Acquired at 23:10 UTC on April 17, 2024