Akan volcano alert level raised, Hokkaido, Japan

Akan volcano alert level raised, Hokkaido, Japan

The Japan Meteorological Agency (JMA) has issued a Near-crater Warning for Akan volcano (Meakandake) at 03:30 UTC on November 23, 2018. The decision was made due to increased seismic activity at the volcano.

A similar event occurred in 2015 when the increased seismic activity took place together with increased temperatures and fumarolic activity.

The last eruption of this volcano took place from November 18 to 28, 2008 (VEI 1). On November 28, 2008, ash plumes rose to an altitude of 2 km (6 600 feet). Ash was deposited on the eastern flank up to 4 km (2.5 miles) away from the crater.

Akan is a 13 x 24 km (8 x 15 miles) caldera located immediately SW of Kussharo caldera. The elongated, irregular outline of the caldera rim reflects its incremental formation during major explosive eruptions from the early to mid-Pleistocene. 

Growth of four post-caldera stratovolcanoes, three at the SW end of the caldera and the other at the NE side, has restricted the size of the caldera lake. Conical Oakandake was frequently active during the Holocene.

The 1 km (0.62 miles) wide Nakamachineshiri crater of Meakandake was formed during a major pumice-and-scoria eruption about 13 500 years ago.

Within the Akan volcanic complex, only the Meakandake group, east of Lake Akan, has been historically active, producing mild phreatic eruptions since the beginning of the 19th century. Meakandake is composed of nine overlapping cones.

The main cone of Meakandake proper has a triple crater at its summit. Historical eruptions at Meakandake have consisted of minor phreatic explosions, but four major magmatic eruptions including pyroclastic flows have occurred during the Holocene.

Featured image credit: Lee Siebert/Smithsonian Institution


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