Report on Iliwerung (Indonesia) — 14 August-20 August 2013
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 14 August-20 August 2013
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2013. Report on Iliwerung (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 14 August-20 August 2013. Smithsonian Institution and US Geological Survey.
8.532°S, 123.573°E; summit elev. 583 m
All times are local (unless otherwise noted)
CVGHM reported that observers at a post 590 m a.s.l. and 6 km away from Iliwerung reported that diffuse fumarolic emissions from the crater were visible during the mornings from 1 to 19 August. Seismicity fluctuated during the month, but 81 shallow volcanic earthquakes were detected between 1606 and 1741 on 19 August, compared to a total of 30 the previous 18 days. The Alert Level was raised to 2 (on a scale of 0-4).
At 0714 on 20 August an eruption from the submarine SE flank vent, Hobal, ejected dense white plumes 2 km a.s.l. that drifted S. Incandescence at sea level was observed at 0746, and the water around the eruption site turned yellow. Fishermen and tourists were not permitted within a 2-km-radius of Hobal.
Geological Summary. Constructed on the southern rim of the Lerek caldera, Iliwerung forms a prominent south-facing peninsula on Lembata (formerly Lomblen) Island. Craters and lava domes have formed along N-S and NW-SE lines on the complex volcano; activity has been observed at vents from the summit to the submarine SE flank. The summit lava dome was formed during an eruption in 1870. In 1948 the Iligripe lava dome grew on the E flank at 120 m elevation. Beginning in 1973-74, when three ephemeral islands were formed, submarine eruptions began on the lower ESE flank at a vent named Hobal; several other eruptions have since taken place at this vent.