Increased seismic activity at Ranakah volcano prompts Alert Level 2, Indonesia
Increased seismic activity was observed at Indonesia’s Ranakah volcano over the past month, prompting the Center for Volcanology and Geological Hazard Mitigation (PVMBG) to raise the Alert Status for the volcano from Level 1 to Level 2 on December 3, 2024. The last eruption at this volcano took place in 1991.
Satellite image of Ranakah volcano on October 12, 2024. Image credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers
Increased seismic activity was observed at Ranakah volcano between November 1 and December 2, with a significant rise in both local and distant tectonic earthquakes. Low-frequency (LF) earthquakes also increased notably compared to October.
During this period, 18 LF quakes, 1 shallow volcanic earthquake, and 25 deep volcanic earthquakes were recorded. Additionally, earthquakes related to tectonic activity included 57 local tectonic earthquakes and 132 distant tectonic earthquakes.
This prompted PVMBG to raise the Alert Level for Ranakah to 2 and advise citizens to avoid approaching, entering, or conducting activities within a 1 km (0.6 miles) radius of the active crater.
The increase in LF quakes suggests resonance from the flow of fluids such as magma, gas, and water vapor within fractures or cavities beneath Ranakah. Additionally, the occurrence of shallow and deep volcanic earthquakes indicates rock fracturing caused by the influx of shallow and deep magma.
The Anak Ranakah lava dome formed in 1987 in an area with no previously recorded eruptions, located at the base of the large older lava dome of Gunung Ranakah.
An arcuate group of lava domes extends approximately 12 km (7.5 miles) west from Gunung Ranakah to Poco Mandosawa, situated on the northern outer flanks of the poorly known Poco Leok caldera on western Flores Island.
The most recent eruption, with a Volcanic Explosivity Index (VEI) of 1, occurred in 1991. During this event, periodic weak ash emissions reaching heights of 15 – 20 m (49 – 65.6 feet) continued in March from cracks in the lava dome, although no dome growth was observed.
On average, five tectonic earthquakes, two volcanic earthquakes, and one earthquake associated with dome collapse were recorded daily.
Additionally, between 1987 and 1989, a VEI 3 eruption was reported at the volcano.
References:
1 Increase in Activity Level of G. Anak Ranakah From Level I (Normal) to Level 2 (Alert) Effective from December 3, 2024 at 08:00 WITA – PVMBG – December 3, 2024
2 Global Volcanism Program, 1991. Report on Ranakah (Indonesia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:3. Smithsonian Institution.
I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.
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