A thin volcanic plume stretches from the snow-covered lava dome of the Shiveluch Volcano and extends over the Gulf of Kamchatka, giving clear evidence that explosive-extrusive eruptions continue on Russia’s Kamchatka Peninsula. This true-color image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite as it passed overhead just after midnight UTC on September 29, 2010. Two hours later, a 4.8 magnitude earthquake was reported near Ozero Nerpich’e, the large lagoon which lies to the east of Shiveluch. A wider, but more diffuse volcanic plume also rises from Klyuchevskaya, the snow-covered dome south of Shiveluch.
The Kamchatka peninsula is a volatile tectonic area known for both volcanic activity and earthquakes. One of the driving factors in this volatility is subduction – the process by which one of the Earth’s plates slides beneath another. In general, the Pacific Plate is subducting under the Eurasian Plate. But the tectonics are complex, and earth movement occurs along several blocks, plates and chains in the area.
Many of the most active volcanoes are located in the Central Kamchatka Depression, an area at the edge of a downward traveling piece of the Pacific Plate. It is thought that in this area that fertile mantle – an area that can produce abundant melt – rises up and mixes with water and volatile materials as the Pacific Plate moves downward, producing more melting of the mantle. This can produce a large amount of magma and allows volcanoes in this area to be especially active. It is also thought that slabs of earth may break suddenly as subduction occurs, also causing volcanic activity.
The Kamchatkan Volcanic Eruption Response Team (KVERT) reports that seismic activity of Shiveluch was above background levels last week, with moderate ash plumes occurring all week long. On September 29, the day this image was captured, gas-steam plumes extended about 70 km (43 mi) to the south-east from the volcano. KVERT also warns that ash explosions could occur at any time, with a potential for ash rising higher than 10 km (32,800 ft) and that volcanic activity from Shiveluch could affect international and low-flying aircraft.