Bolshoi Semiachik Volcano | John Seach


Kamchatka, Russia

54.32 N, 160.02 E
summit elevation 1720 m

Bolshoi Semiachik Volcano is located in eastern Kamchatka, 20 km SW of Uzon caldera and 25 km NE of Maly Semiachik.

The volcano contains a 10 km wide caldera. The volcano basement diameter is 15 km with an absolute height of over 1700 m. Bolshoi Semiachik consists of numerous smaller stratovolcanoes which merge at their base. Seven cone-shaped stratovolcanoes have been identified with diameters of 3-9 km.

Bolshoi Semiachik (Zubchatka) is the largest and highest of the stratovolcanoes (1720 m). The second largest volcanic structure is formed by Zapadny Barany volcano (1426 m) and Vostochny volcano (1320 m).

Problemmatichny is the third largest volcano (1317 m). It is located in the south of the caldera and has a relative height of 800-900 m.

The central part of Bolshoi Semiachik is occupied by four similar volcanoes, with diameters of about 3 km and relative heights of 200-500 m.

On the southeast side and on the edge of the caldera are numerous solfatara and hot springs, which comprises on of the largest hydrothermal systems in Kamchatka.

Thermal Activity
Strong solfatara activity is present at Bolshoi Semiachik Volcano. Paryashchaya Dolina (Steaming Valley) is 250 m in diameter, and contains steaming, boiling springs, and mudpots. Verkhneye (upper) thermal field covers 500 m of summit ridges and ravines of Burlyashchy and contains several hot areas.

1954 Eruption
A possible eruption of steam and cinders occurred in 1954.

Further reading
Zhitova, Elena, et al. "Minerals of Bolshoi Semiachik geothermal fields (Central Kamchatka, Russia)." EGU General Assembly Conference Abstracts. 2021.

Grib, E.N. and Leonov, V.L., 1993. Ignimbrites of the Bolshoi Semiachik caldera, Kamchatka: Composition, structure and origin. Volcanol. Seismol, 14(5), pp.532-550.

Bolshoi Semiachik Volcano Eruptions

1954?, 4450 BC?