A new eruption that began at Chikurachki on 18 April 2003 was reported by the Kamchatka Volcanic Eruptions Response Team (KVERT) and the Alaska Volcano Observatory (AVO). The most recent previous eruption occurred in early 2002 (BGVN 27:01 and 27:04). Ash explosions were seen by observers on Paramushir Island, and at 1500 and 2000 ashfall was observed in Podgorny town and Cape Vasiliev. The Aviation Meteorological Center at Yelizovo Airport reported that on 19 April ash plumes rose 2,000 m above the crater. According to satellite data from the USA, distinct volcanic events were detected at approximately 2300 on 19 April, 0200 on 20 April, and 0430 on 20 April (1200, 1500, and 1730 UTC, 19 April), with the ash moving towards the SE. Interpretation of satellite imagery revealed plumes extending more than 50 km SE and SSE during 18-19 April, with the longest reaching more than 250 km at 1501 on the 19th.

Visual data from Vasiliev Cape and Paramushir Island on 22 April showed a white gas-and-steam plume that rose 500 m above the crater. According to satellite data from the USA and Russia, ash plumes less than 100 km long were moving SE and E during 22-25 April. Longer plumes on 25 April were directed NNE. Observers from Vasiliev Cape noted a white plume rising ~500 m above the crater on 27 April. On 28 April residents in Severo-Kurilsk observed a very fine layer of gray ash (less than 1 mm thick) near the city, 3 km S of the volcano. The longest plume seen in satellite imagery during April was more then 300 km long when observed at 2028 on 29 April.

Geological Summary. Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is a relatively small cone constructed on a high Pleistocene edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the young cone give it a distinctive red color. Frequent basaltic Plinian eruptions have occurred during the Holocene. Lava flows have reached the sea and formed capes on the NW coast; several young lava flows are also present on the E flank beneath a scoria deposit. The Tatarinov group of six volcanic centers is located immediately to the south, and the Lomonosov cinder cone group, the source of an early Holocene lava flow that reached the saddle between it and Fuss Peak to the west, lies at the southern end of the N-S-trending Chikurachki-Tatarinov complex. In contrast to the frequently active Chikurachki, the Tatarinov centers are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of an eruption around 1690 CE from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.

Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanic Geology and Geochemistry (IVGG), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.