Report on Rinjani (Indonesia) — 29 April-5 May 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 April-5 May 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Rinjani (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 April-5 May 2009. Smithsonian Institution and US Geological Survey.
8.42°S, 116.47°E; summit elev. 3726 m
All times are local (unless otherwise noted)
CVGHM reported than during 29 April-2 May seismicity from Rinjani increased and tremor was detected. On 2 May, an eruption produced dense brown "smoke" that rose 1 km from Barujari cone and was accompanied by a booming noise. On 4 May, an eruption of ash produced a white to brown plume that rose 500-700 m above the cone and drifted N. Fog often prevented observations. The Alert Level was raised to 2 (on a scale of 1-4). According to a news article, ash fell in the local village of Senaru.
Geologic Background. Rinjani volcano on the island of Lombok rises to 3726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the west side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak (Samalas) caldera. The caldera formed during one of the largest Holocene eruptions globally in 1257 CE, which truncated Samalas stratovolcano. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the east end of the caldera. Historical eruptions dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.