Geologic Background:
The small conical volcano of Soputan on the
southern rim of the Quaternary Tondano caldera is one of
Sulawesi's most active volcanoes. The youthful, largely
unvegetated Soputan volcano is located SW of Sempu
volcano and was constructed at the southern end of a
SSW-NNE trending line of vents.
Historic Activity:
- Has erupted at least 26 times since the 1700's,
generally with moderately explosive ash emission and
earthquakes.
- During historical time the locus of eruptions has
included both the summit crater and Aeseput, a prominent
NE flank vent that formed in 1906 and was the source of
intermittent major lava flows until 1924.
Recent Activity:
- Soputan erupted from May 24 to Man 26, 1984 when a
ash column rose to 4 km. A 5-hour explosive eruption
occurred on Aug. 31, 1984.
- On April 22, 1989, Soputan erupted for the first time
since May 1985, sending ash and lapilli to 1000-1500
meters above the summit. The eruption was preceded by a
significant increase in volcanic tremor since January.
Eruptive activity and tremor ended on April 24. Tremor
began again on June 6 but surface activity was limited to
weak emission of fumes.
- On May 22-24, 1991, following 2 years of inactivity,
loud booming sounds and night flow were reported from the
main crater. Red glow ended on May 29 but ash emissions
continued into June. Crater floor covered by 50 m of new
lava. Reports of incandescent tephra ejection and night
glow in December.
- Satellite imagery confirmed the presence of an
eruption plume on March 15, 1996. Other reports indicated
the ash cloud reached an altitude of 4.5 km.
- During the period May-July 2000 there was continued
dome growth, lava flows, and several explosions. The
level of activity began to increase during the year with
ash eruptions in October.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 7, No. 8 to V. 14,
No. 5)
- Global Volcanism Network (V. 16, No. 5 to V. 25, No.
10)
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