Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 10, October 1995
Merapi (Indonesia)  Pyroclastic flows travel down two river

Java, Indonesia
7.54S, 110.44E; summit elev. 2,911 m

During August-October 1995 pyroclastic flows (~glowing
avalanches~) continued flowing down the Boyong River; others
entered the Krasak River and reached ~1-1.5 km from the
source. Seismic activity was dominated by multiphase and
lava-avalanche (rockfall) earthquakes. The number of
multiphase earthquakes increased in October to 793 events,
compared to 186 in September. Earthquakes associated with
lava avalanches or rock falls gradually decreased from 1,195
events in August to 806 in September and 605 in October
(figure 4). Shallow volcanic (B-type) earthquakes (~1 km
depth) were recorded on 25 October and a deep volcanic (A-
type) earthquake (2.7 km depth) was detected on 30 October.
Observations in October indicated an inflation associated
with 40 ~rad of tilt. Measurement of SO2 by COSPEC indicated
that the emission rate during October fluctuated between 18
and 112 tons/day (average 63).

Merapi is one of the most active volcanoes in Indonesia. The
stratovolcano has an exposed, summit lava dome, the source
of abundant glowing avalanches directed down its S to W
slopes toward  a region settled by at least 50,000 people.
In historical time, instability of the growing dome has led
to pyroclastic flows that have caused many fatalities.
Collapse of the growing lava dome in November 1994 triggered
pyroclastic flows that killed  64 people (Bulletin v. 19,
nos. 10 and 12). Additional collapses continued into January
1995 (Bulletin v. 20, no. 2).

Information Contact: Wimpy S. Tjetjep (Director),
Volcanological Survey of Indonesia (VSI), Jalan Diponegoro
57, Bandung, Indonesia.