An eruption at Sheveluch has been ongoing since 1999, and the activity there was previously described through February 2015 (BGVN 42:01). During March-August 2015, the same type of activity prevailed, with lava dome extrusion, incandescence, hot block avalanches, fumarolic activity, and occasional strong explosions that generated ash plumes. Most of the following data comes from Kamchatka Volcanic Eruption Response Team (KVERT) reports. During this period the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

KVERT reported that during 27 February-15 May 2015, lava-dome extrusion onto the N flank continued to be accompanied by incandescence, hot block avalanches, and fumarolic activity. This activity diminished somewhat during 22 May-14 July, when lava-dome extrusion was accompanied only by fumarolic activity. However, heightened activity resumed during 15 July-31 August, when KVERT reported that lava-dome extrusion was accompanied by fumarolic activity, dome incandescence, and hot avalanches.

Between 28 February and the middle of April 2015, strong explosions generated ash plumes that rose to 7-12 km altitude. Ash drifted as much as 885 km in various directions, and ash fell in Ust-Kamchatsk (85 km SE) at least twice in March. Based on KVERT reports, ash plumes on 15 June and 5-6 July only rose as high as 3.3-5 km in altitude.

A daily thermal anomaly was detected 27 February-15 May, except when cloud cover obscured views. During 16-30 May, thermal anomalies were only detected occasionally in satellite images, but became more frequent thereafter, depending on cloud cover. KVERT reported that during 10 July-31 August, satellite images again detected an almost daily thermal anomaly over the dome.

Thermal anomalies based on MODIS satellite instruments analyzed using the MODVOLC algorithm were infrequent during the reporting period, in contrast to the almost daily hotspots reported by KVERT. One hotspot was detected in March, April, and June, none in May, four in July, and eight in August.

Geological Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far Eastern Branch, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/kvert/); Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).