KVERT reported that seismic activity at Koryaksky was at background levels during 27 March-3 April. Gas plumes containing a small amount of ash rose to an altitude of 4 km (13,200 ft) a.s.l. and drifted E, SE, S, and W during the reporting period. During 27-28 and 31 March, and 1-2 April, gas-and-ash plumes were also seen on satellite imagery and drifted 313 km E, in southerly directions. The Level of Concern Color Code remained Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Geological Summary. The large symmetrical Koryaksky stratovolcano is the most prominent landmark of the NW-trending Avachinskaya volcano group, which towers above Kamchatka's largest city, Petropavlovsk. Erosion has produced a ribbed surface on the eastern flanks of the 3430-m-high volcano; the youngest lava flows are found on the upper W flank and below SE-flank cinder cones. Extensive Holocene lava fields on the western flank were primarily fed by summit vents; those on the SW flank originated from flank vents. Lahars associated with a period of lava effusion from south- and SW-flank fissure vents about 3900-3500 years ago reached Avacha Bay. Only a few moderate explosive eruptions have occurred during historical time, but no strong explosive eruptions have been documented during the Holocene. Koryaksky's first historical eruption, in 1895, also produced a lava flow.