Report on Tengger Caldera (Indonesia) — 22 September-28 September 2021
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 22 September-28 September 2021
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2021. Report on Tengger Caldera (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 22 September-28 September 2021. Smithsonian Institution and US Geological Survey.
7.942°S, 112.95°E; summit elev. 2329 m
All times are local (unless otherwise noted)
PVMBG reported that during 21-27 September white gas-and-steam plumes rose as high as 400 m above the rim of Tengger Caldera’s Bromo cone and drifted SW, W, and NW. White-and-gray plumes rose as high as 500 m during 22-23 September. A weak thermal anomaly was visible in Sentinel-2 infrared satellite images on 22 and 27 September. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to stay outside of a 1-km radius of the crater.
Geological Summary. The 16-km-wide Tengger caldera is located at the northern end of a volcanic massif extending from Semeru volcano. The massive volcanic complex dates back to about 820,000 years ago and consists of five overlapping stratovolcanoes, each truncated by a caldera. Lava domes, pyroclastic cones, and a maar occupy the flanks of the massif. The Ngadisari caldera at the NE end of the complex formed about 150,000 years ago and is now drained through the Sapikerep valley. The most recent of the calderas is the 9 x 10 km wide Sandsea caldera at the SW end of the complex, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most active and most frequently visited volcanoes.