Report on Semeru (Indonesia) — 22 April-28 April 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
22 April-28 April 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Semeru (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 April-28 April 2015. Smithsonian Institution and US Geological Survey.
8.108°S, 112.922°E; summit elev. 3657 m
All times are local (unless otherwise noted)
PVMBG reported that white plumes and grayish white plumes from Semeru rose as high as 600 m above the crater during January-20 April, although inclement weather often prevented observations. Seismicity fluctuated, and was dominated by explosions and emission signals. During January incandescent avalanches from lava-flow fronts traveled 100-300 m. Eruptions were heard five times during 16-28 February. Nine explosions were heard during 1-15 March; minor ashfall from one of the explosions fell on the observation post. The Alert Level remained at 2 (on a scale from 1-4); visitors and residents were warned to avoid the SE flank within 4 km of the crater.
Geological Summary. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.