Continuous volcanic tremor and night glow over the crater began in March. Tremor and the number of explosive earthquakes increased from late March through May. During this period, the amplitude of volcanic tremor at 14 km distance and the maximum amplitude of explosive earthquakes reached 2 and 5 µ respectively. Since mid-May, a cinder cone has been visible in the central part of the crater. On 22 May, as moderate Strombolian activity continued, lava began to pour into the NW valley.

Further Reference. Tokarev, P.I., 1985, Eruption of Kliuchevskoi volcano in March-April 1984 and estimation of the observation data: Volcanology and Seismology, no. 1, p. 106-108.

Geological Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Information Contacts: B. Ivanov, IVP.