Avachinsky

Kamchatka

SUMMARY:

Type: composite with caldera
Activity: active
Last Eruption: 1991 AD
Rock Type: ?
Eruptive Volume: ? cu km
Location Map from Xerox PARC
Latitude: 53.25 N
Longitude: 158.85 E

GEOLOGIC HISTORY

Avachinsky is a large strato-volcano that began to form 60-70,000 years ago. A major debris avalanche about 30-40,000 B.P. buried an area of about 500 square km south of the volcano, including the land now occupied by Petropavlovsk-Kamchatskii, about 25 km SW. A powerful explosive eruption about 6,400 years ago (based on corrected radiocarbon dating) produced a large caldera, inside which the presently active cone has grown.

Historic Activity: There have been 14 eruptions between 1737 and 1945. Avachinsky's previous (and largest historic) eruption, in February 1945, produced about 0.25 cubic km of tephra.

Recent Activity:

  • An eruption began on Jan. 13, 1991 with explosions that ejected ash clouds to 4-5 km above the crater. Ash fell on Petropavlovsk, 30 km SSW. The eruption lasted until Jan. 30, 1991, filling the summit crater (400-500 m in diameter) with about 21,000,000 metric tons of lava. Circumferential and radial fissures 6 m deep covered the surface of the lava dome. Lava overflowed the S rim, feeding a flow that advanced 1.5 km down the SSE flank and short flows on the SW flank. Numerous fumaroles developed around the dome's margins.
  • Continued fumarolic activity in reported in 1993-1998.
  • A distinct change in seismic activity began on Dec. 3, 1998.

Data Sources

  • Global Volcanism Network (V. 15, No. 12 to V. 23, No. 11).

ADDITIONAL INFORMATION

Last Update: 2/21/00