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Report on Ketoi (Russia) — October 2018


Bulletin of the Global Volcanism Network, vol. 43, no. 10 (October 2018)
Managing Editor: Edward Venzke. Research and preparation by Sara Arav-Piper.

Ketoi (Russia) Plume of uncertain composition reported based on satellite data one day in September

Please cite this report as:

Global Volcanism Program, 2018. Report on Ketoi (Russia) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 43:10. Smithsonian Institution.



47.35°N, 152.475°E; summit elev. 1172 m

All times are local (unless otherwise noted)

Gas-and-steam emissions were previously reported at Ketoi (figure 1) in January, July, and August 2013 (BGVN 40:09). Intense fumarolic activity originating from the same area, the N slope of Pallas Peak, was reported in 1981, 1987, and 1989. Based on a report from the Sakhalin Volcanic Eruption Response Team (SVERT) using Himawari-8 imagery, the Tokyo VAAC reported an ash plume on 21 September 2018 which drifted to the NE; however, evidence of the plume could not be confirmed by the VAAC from satellite imagery. The original VONA (Volcano Observatory Notice for Aviation) issued by SVERT noted a volcanic cloud without a specific mention of ash, but also remarked that thermal anomalies had been observed on 17 and 20 September.

Figure (see Caption) Figure 1. Natural color Sentinel-2 satellite image of Ketoi on 18 September 2018. A large freshwater lake can be seen SW of the Pallas Peak andesitic cone, which also hosts a crater lake. Lava flows originating from the younger cone extend primarily N to SW, and a white fumarolic area is immediately NE of the crater. The island is approximately 10 km in diameter. Courtesy of Sentinel Hub Playground.

Geological Summary. 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 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.

Information Contacts: Sakhalin Volcanic Eruption Response Team (SVERT), Institute of Marine Geology and Geophysics, Far Eastern Branch, Russian Academy of Science, Nauki st., 1B, Yuzhno-Sakhalinsk, Russia, 693022 (URL:,; Sentinel Hub Playground (URL: