Report on Ketoi (Russia) — 31 July-6 August 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 July-6 August 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Ketoi (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 31 July-6 August 2013. Smithsonian Institution and US Geological Survey.
47.35°N, 152.475°E; summit elev. 1172 m
All times are local (unless otherwise noted)
SVERT reported that during 29-31 July a thermal anomaly from Ketoi's Pallas Peak was observed in satellite imagery. Gas-and-steam emissions were also observed on 29 July, and possibly observed on 31 July and 4 August. The Aviation Color Code remained at Yellow.
Geologic Background. The circular, 10-km-wide Ketoi island, which rises across the 19-km-wide Diana Strait from Simushir Island, hosts of one of the most complex volcanic structures of the Kuril Islands. The rim of a 5-km-wide Pleistocene caldera is exposed only on the NE side. A younger 1172-m-high stratovolcano forming the NW part of the island is cut by a horst-and-graben structure containing two solfatara fields. A 1.5-km-wide freshwater lake fills an explosion crater in the center of the island. Pallas Peak, a large andesitic cone in the NE part of the caldera, is truncated by a 550-m-wide crater containing a brilliantly colored turquoise crater lake. Lava flows from Pallas Peak overtop the caldera rim and descend nearly 5 km to the SE coast. The first historical eruption of Pallas Peak, during 1843-46, was its largest.