A few gas-and-steam plumes from Ebeko were reported during February-April 2004 (BGVN 29:04). The most recent previous eruption was in January 1991. On 30 January 2005 the Kamchatka Volcanic Eruptions Response Team (KVERT) raised the Concern Color Code at Ebeko from Green to Yellow after reports of a strong smell of sulfur on 27 and 28 January in the town of Severo-Kurilsk, ~ 7 km from Ebeko. Observations by Leonid and Tatiana Kotenko in Severo-Kurilsk during May-July 2004 included occasional gas-and-steam plume rising as high as 250 m above the volcano during clear weather and fumarolic plumes moving close to the ground. There was no visible activity in August, but a few plumes were seen again from September to November.

During 28 January, a white gas-and-steam plume was seen from Severo-Kurilsk rising 400 m above the volcano. Summit observations the next day revealed a yellow-gray, 5-m-diameter, column rising 300 m from a vent on the NE side of the active crater. Three ash layers 2-3 mm thick were noted 10 m from the vent, and ash extended ~ 500 m E into the crater. At this time a new 7 x 12 m turquoise lake had developed in the SW part of the active crater. The lake disappeared on 30 January, and there was intensive fumarolic activity where it had been. Shallow earthquakes were recorded at the Severo-Kurilsk seismic station.

On 1 February gas-and-steam plumes rose to 450 m above Ebeko's crater and drifted NE. On 7 February a small emission of steam, gas, and possibly ash rose ~ 1 km above the crater and drifted ~ 12 km SE. On 8 and 9 February plumes rose to 600 m and thin ash deposits were noted in the town of Severo-Kurilsk.

The following information came to KVERT from observers in Severo-Kurilsk (Leonid and Tatiana Kotenko). On 15-16 February a dark-gray column rose up to 500 m above the crater. A dark-gray plume extended 6 km E and a light-gray plume 7 km SE. On 16 February ashfall together with snowfall was noted over the strait to the E of Paramushir Island. On 17 February a white column up to 250 m above the crater was observed. On 12 February and 16-17 February a strong smell of a H₂S was noted at Severo-Kurilsk. On 18-19 February white gas-and-steam columns 5 m in diameter rose from the two vents up to 450 m above the crater and a new lake (10 x 10 m) on the floor of the active crater was observed. On 25 February white gas-and-steam plumes rose to 450 m and 1,000 m above the crater. Gas-and-steam plumes were also observed on 1-2, 4-5, and 9 March. No ash was seen. A strong smell of H₂S was noted at Severo-Kurilsk on 25 February and 2 March.

About 20 seismic events of less than Ml 2.0 were observed during 1-9 March at the Severo-Kurilsk seismic station. No seismic activity was observed from 12 to 14 March. On 15 March two seismic events were noted. There was no seismicity during 18-25 March, so KVERT reduced the hazard status from Yellow to Green, the lowest level.

The Russian Emergency Situations Ministry's Sakhalin department reported renewed activity on 27 June in the form of emission clouds rising to a maximum height of 200 m above the crater and drifting SW. KVERT did not report any activity, and the Concern Color Code for Ebeko remained at Green.

Geological Summary. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

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