A relatively strong explosion took place at Sakurajima volcano, Aira caldera, Japan at 22:46 UTC on September 15, 2019 (07:46 LT, September 16).

According to the Tokyo VAAC, the ash plume is reaching 4 000 m (13 000 feet) above sea level, extending SW. This is 2 880 m (9 450 feet) above the crater.

Volcanic ash is continuously observed in satellite imagery, the center said 05:58 UTC, September 16.

Sakurajima erupting on September 16, 2019. Credit: NASA Terra/MODIS

An explosion at Minamidake crater on September 3 generated an ash plume that rose 1.9 km (6 230 feet) above te crater and ejected material as far as 900 m (3 000 feet) from the vent. Very small eruptive events were recorded from September 6 to 9.

JMA reported that at 1549 on 3 September an explosion at Minamidake crater (at Aira Caldera’s Sakurajima volcano) generated an ash plume that rose 1.9 km above the crater rim and ejected material as far as 900 m from the vent. Very small eruptive events were detected during 6-9 September.

The volcano alert level remains at 3 of 5 (Near-crater Warning - Do not approach the volcano: Refrain from entering the danger zone).

Geological summary

The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km (10.5 x 14.3 miles) caldera about 22 000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones.

The construction of Sakurajima began about 13000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake.

Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km (5 miles) from the summit. The largest historical eruption took place during 1471-76. (GVP)

Featured image: Sakurajima erupting on September 16, 2019. Credit: NASA Terra/MODIS