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Report on Tengger Caldera (Indonesia) — 8 February-14 February 2023

Tengger Caldera

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 8 February-14 February 2023
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2023. Report on Tengger Caldera (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 8 February-14 February 2023. Smithsonian Institution and US Geological Survey.

Weekly Report (8 February-14 February 2023)

Tengger Caldera


7.942°S, 112.95°E; summit elev. 2329 m

All times are local (unless otherwise noted)

PVMBG sent a team of scientists to investigate Tengger Caldera’s Bromo cone after an increase in activity was detected on 3 February, characterized by crater incandescence, rumbling sounds, and a strong sulfur dioxide odor. They observed somewhat dense white emissions rising as high as 300 m during 9-12 February and heard moderate-to-strong rumbling noises. A sulfur dioxide odor was strong near the crater and measurements indicated that levels were above the healthy (non-hazardous) threshold of 5 parts per million; differential optical absorption spectroscopy (DOAS) measurements indicated an average flux of 190 tons per day on 11 February. During clear periods the largest solfatara on the NNW part of the crater floor was visible and ranged in temperature from 46 to 66 degrees Celsius based on handheld instruments. Crater incandescence, originating from the solfatara, was visible at night. 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)