Report on Merapi (Indonesia) — 16 April-22 April 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 April-22 April 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Merapi (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 16 April-22 April 2014. Smithsonian Institution and US Geological Survey.
7.54°S, 110.446°E; summit elev. 2910 m
All times are local (unless otherwise noted)
PVMBG reported that Merapi observers at the Ngepos post noted white plumes rising 300 m above the lava dome on 15 April. Seismicity increased during 18-20 April. During 0426-0440 on 20 April an explosion occurred and rumbling was heard in areas as far as 8 km away. Ash plumes were observed from some observations posts, but foggy conditions prevented views from others. Based on satellite images and wind data, the Darwin VAAC reported that an ash plume rose to an altitude of 10.7 km (35,000 ft) a.s.l. and drifted 260 km WNW. PVMBG noted that ashfall was reported in areas within 15 km S, SW, and W. The Alert Level remained at 1 (on a scale of 1-4).
Geologic Background. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequently growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent eruptive activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities during historical time.