Sheveluch erupts ash up to 8.5 km a.s.l., Klyuchevskoy alert level raised, Russia

Two strong eruptions were recorded at Russia's Sheveluch volcano over the past 24 hours. The first one, registered at 20:30 UTC on September 7, sent ash up to 8.2 km (27 000 feet) above sea level, while the second, registered at 10:30 UTC today, sent ash up to 8.5 km (28 000 feet), according to the Tokyo VAAC. Following an eruption at 21:46 UTC on September 7, KVERT raised the Aviation Color Code for nearby Klyuchevskoy volcano from Yellow to Orange.

Ash produced during both eruptions at Sheveluch drifted to the northeast. The explosive-extrusive eruption of the volcano continues, KVERT reported, adding that the Aviation Color Code remains Orange.

Ash explosions up to 10 to 15 km (32 800 – 49 200 feet) a.s.l. could occur at any time, it warned and added that ongoing activity could affect international and low-flying aircraft.

The last time this volcano experienced a powerful eruption was on August 9, 2017, when ash cloud reached an altitude of 12.2 km (40 000 feet) above sea level and drifted SSE.

Explosive activity of Sheveluch volcano on September 7, 2017. Credit: IVS FEB RAS, KVERT (videodata)

The Aviation Color Code for nearby Klyuchevskoy volcano was raised from Yellow to Orange, KVERT reported at 22:13 UTC on September 7, after a strong eruption at 21:46 UTC sent ash up to 7 km (23 000 feet) a.s.l. Volcanic ash drifted to the northeast and was observed until 05:20 UTC on September 8.

Ash explosions up to 8 – 10 km (26 200 – 32 800 feet) could occur at this volcano at any time, affecting international and low-flying aircraft.

Geological summaries

Sheveluch

The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1 300 km³ (311.9 mi³) volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65 000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene (5.6 miles) caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava-dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch.

At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. 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. (GVP)

Klyuchevskoy

Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high (15 862 feet) basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif.

More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3 600 m (1 640 – 11 811 feet) elevation.

The morphology of the 700-m-wide (2 296 feet) summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters. (GVP)

Featured image: Explosive activity of Sheveluch volcano on September 7, 2017. Credit: IVS FEB RAS, KVERT (videodata)