Increased eruptive activity at Lewotobi, Alert Level raised to highest, evacuation orders issued, Indonesia

Eruptive activity at the Lewotobi volcanic complex further increased over the past 10 days, prompting the Volcanology and Geological Disaster Mitigation Center (PVMBG) to raise the Alert Level to the highest (4 of 4) on January 9, 2024.

According to PVMBG, seismicity at Lewotobi increased on December 12, 2023, and was followed by the emergence of “tornillo” earthquakes indicating fluid movement at depth. This activity was followed by a 24-minute-long eruption on December 23 at Lakilaki. A 160 m (525 feet) long fissure on the upper NW flank was visible afterward, emitting dense white plumes up to 300 m (985 feet) above the crater.

A dense white-and-gray ash plume rising to 1 km (3 280 feet) above the summit was reported on December 28. On January 1, 2024, the amplitude of continuous tremors increased and a new vent opened along a fissure located on the upper SSE flank, producing a white, gray, and black ash plume that rose 1 – 1.5 km (3 280 – 4 920 feet) above the summit. As a result, the Alert Level was raised to 3 of 4, and the public was warned to stay 3 km (1.8 miles) away from the Perempuan and Lakilaki craters and an additional 4 km (2.5 miles) from the NNW and SSE flanks of Lakilaki.

The volcano exhibited an increase in the maximum height of ash columns since the start of the year, from 2.4 km (8 000 feet) a.s.l. on January 1 to 4.3 km (14 000 feet) a.s.l. on January 9. This activity was accompanied by increasing tremors, incandescent lava bombs at the peak, and lava flows.

As a result, PVMBG raised the Alert Level from 3 to 4 on January 9 and issued evacuation orders to people living near the volcano.

Local authorities have established two temporary shelters, which are currently accommodating about 5 000 people, local official Benediktus Bolibapa Herin told AFP today, January 10.

People living around Lewotobi and visitors/tourists are advised not to carry out any activities within a 4 km (2.5 miles) radius from the main crater and 5 km (3.1 miles) in the northwest-north sector.

PVMBG head Hendra Gunawan has warned locals to be vigilant for potential flooding caused by volcanic mudflows entering rivers. He also recommended that people wear masks to protect their respiratory systems from volcanic ash.

The Lewotobi twin volcanoes, also known as “husband and wife” or Lewetobi, are situated on eastern Flores Island. This volcanic complex comprises two stratovolcanoes, Lewotobi Lakilaki and Lewotobi Perempuan, with their summits located less than 2 km (1.2 miles) apart along a northwest-southeast line.

The conical-shaped Lakilaki volcano has shown frequent activity throughout the 19^th and 20^th centuries. In contrast, the taller and broader Perempuan volcano has only had two recorded eruptions in historical times. Both volcanoes have developed small lava domes within their crescentic summit craters, which open to the north, during the 20^th century. Additionally, a notable flank cone, named Iliwokar, is present on the eastern flank of Perempuan.

References:

¹ Global Volcanism Program, 2023. Report on Lewotobi (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 27 December-2 January 2024. Smithsonian Institution and US Geological Survey.

² Indonesia’s Lewotobi Laki-Laki volcano erupts, on highest alert level – AFP – January 10, 2024

³ Lewotobi – Geological summary – GVP

Featured image credit: PVMBG