A small hot area, apparently centered on the summit, was first noted on the thermal infrared band of a NOAA 6 satellite image on 21 December at 1057, and a hot spot was present 22 hours later. An average temperature of 320°C within a given image element (or "pixel", corresponding to a 1.1 x 1.1 km ground area) will saturate the sensors for this band, so it is not possible to determine the actual temperature of the heat source nor its true dimensions. On the next image, at 1233 on 22 December, the hot spot was accompanied by a diffuse plume that extended about 350 km SE. The hot spot had decreased in size 24 hours later, and the plume was smaller (detectable only to 60 km to the E) and more diffuse. Clouds partially obscured the volcano for the next several daily images, but a small plume seemed to be present. On the next clear-weather image, at 1400 on 28 December, there appeared to be a small warm area at the summit, but no plume was evident. No additional activity has been observed on satellite imagery. There have been no reports from ground observers.

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: M. Matson, NOAA/NESS.