Shinmoedake volcano starts erupting after 6 years of quiescence, Japan

Shinmoedake volcano starts erupting after 6 years of quiescence, Japan

Following increased seismic activity detected since September 23, 2017, Shinmoedake volcano (Kirishimayama) in Kyushu, Japan started erupting at 20:34 UTC on October 10, 2017, coating nearby cities and towns in a thin layer of ash. The last eruption of this volcano occurred on September 7, 2011.

Increase in the number of volcanic earthquakes under the volcano was first detected on September 23, 2017. It further increased on October 4, prompting JMA to conduct a field survey on October 5 when they observed fumarolic activity and weak thermal anomalies. At 23:55 JST that day, JMA raised the alert level from 1 to 2, restricting entry to areas near the crater. 

Earthquakes under Shinmoedake volcano before eruption on October 10, 2017

Earthquakes under Shinmoedake volcano before eruption on October 10, 2017

Shinmoedake started erupting for the first time in six years at 20:34 UTC on October 10 (05:34 JST, October 11), prompting JMA to raise the volcanic alert level to 3. This is the first time this volcano is on Alert Level 3 since October 2013. Alert Level 3 means residents and tourists are not allowed to approach the mountain within 2 km (1.2 miles) due to the possibility of flying rocks and pyroclastic flows.

JMA said that the plume from the eruption is rising 300 m (984 feet) above the crater. This is 2000 m (6 561 feet) above sea level. A small amount of ash fell in three cities and the town of Takaharu in Miyazaki, JMA added.

Kyodo reported that some people in Takaharu walked while holding an umbrella as volcanic ash fell on roads. Yoshinari Imanishi, 66, a senior official of a local tourism association, expressed concern about the possible negative impact from the eruption, saying, "We were hit by accommodation cancellations six years ago. I hope (the eruption) will not affect the autumn outing season."

Ash plume rising from Shinmoedake volcano on October 11, 2017

Ash plume rising from Shinmoedake volcano on October 11, 2017. Credit: 谷山天一(たにやまひろかず)‏

According to local police, there are no reports of injuries or damage.

Geological summary

Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km (12.4 - 18.6 miles). The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1700-m-high (5 577 feet) Karakunidake being the highest.

Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century. (GVP)

Featured image: Eruption of Shinmoedake volcano on October 11, 2017

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