A strong eruption started at Russia's Sheveluch volcano at 17:50 UTC on September 11, 2017. Ash cloud drifted east and reached an altitude of up to 10 km (33 000 feet).
The eruption lasted some 30 minutes and was recorded by webcams and satellites.
Satellite data show an ash cloud about 70 km (43 miles) east of the volcano, KVERT said in their VONA issued 20:24 UTC on September 11.
The Aviation Color Code for Sheveluch remains at Orange.
Ash explosions up to 10 - 15 km (32 800 - 49 200 feet) a.s.l. could occur at any time. Ongoing activity could affect international and low-flying aircraft.
Volcanic ash is continuously observed on satellite imagery, the Tokyo VAAC reported 06:00 UTC on September 12.
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)
Featured image: Eruption of Sheveluch volcano, Russia on September 11, 2017. Credit: KVERT & Weathernews INC. (via CultureVolcan)