Geologic Background:
Sabancaya, located on the saddle between
6288-m-high Ampato and 6025-m Hualca Hualca, is the
youngest of these Holocene volcanic centers. It is the
only one to have erupted in historical time. The
5967-m-high Sabancaya, meaning "tongue of fire" in the
Quechua Indian language. Holocene activity has consisted
of plinian eruptions followed by emission of voluminous
trachytic and dacitic lava flows, which form an extensive
15-km-wide apron around the volcano. It is a biotite-rich
dacite cone, overlying young lava flows about 200 m thick
and older, more extensive flows about 20 m thick.
Historic Activity:
- Early church records document previous eruptions in
1750 and July 1784, when earthquakes were felt and alpaca
were killed. The name Sabancaya ("Tongue of Fire" in
Quechua) first appeared in records in 1595, suggesting
prior activity.
Recent Activity:
- Began strong fumarolic activity in December
1986.
- Eruption began on May 19, 1990. Series of increasing
explosions and ash eruptions was continued through end of
June, with decreasing activity in July and the slowing
increasing activity until November.
- In November and December 1991 several eruptions
occurred which produced heavy ash plumes rising to 5-8
km. Activity has continued into 1991 with frequent
mudflows and earthquake swarms also occurring.
- Activity began to increase in February 1992 resulting
in evacuation of nearby towns due to ash fall.
- An ash explosion was observed on March 5, 1994. The
eruption column rose to a height of 2.5 km and fed a dark
gray plume. Another eruption was observed on March 7.
Similar activity has been occurring since December
1992.
- Eruptions were continuing in May 1995. Aviation
reports of ash-bearing plumes on May 1 (5.5 km) and May 2
(7.3 km)
- Eruption of gas and ash cloud during September
1998.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 13, No. 6)
- Global Volcanism Network (V. 15, No. 5 to V. 25, No.
5).
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