Japan Sakurajima Volcano Eruption: The Sakurajima volcano in Japan on July 24th produced an unusually large volcanic eruption

Its eruptions have largely consisted of a series of so-called volcanic explosions, where a small plug of lava or volcanic material is cleared once every few hours, generating a large explosion and on occasion, pyroclastic flows. Generally speaking, 100 to 10 of these explosions occur each year, so the Kurajima is mostly kept at an alert level of three on a one to five scales. This carries with it a two-kilometer exclusion zone, as this radius of twelve represents the typical maximum distance.

 Bombs of lava and boulders of rock thrown by explosions can travel along with occasional pyroclastic flows.  However, on July 24, something changed. At the local time, Sakurajima produced a powerful explosion, sending a plume of ash to a height of three 0 meters or 9842 ft. More importantly, this explosion was unusually powerful, causing large chunks of rock, which were up to the size of boulders to fall up to 2500 meters distant. Since a number of people live within or very close to this radius, and the threat of a far more powerful explosion exists, Sakurajima's alert level was raised from three to five. This was the first time the Korea Jimmy's alert level had been raised to the maximum level since the current Japan volcano rating system was implemented.

 Scientists immediately ordered evacuations for residents within 3 currently Erupting, Manami Daki, and secondary Shoa summit craters. This meant that several areas of dense structures were evacuated, including parts of Eriura and Farossato towns. In addition, residents in the densely populated city of Kagoshima City and Kagoshima Prefecture were advised to remain cautious, as both areas could be affected by falling volcanic ejecta if an even larger explosion does occur. For context, the Sakurajima volcano is located in southern Japan and south central Kyushu. It completely formed in the last 130 years, constructing two separate peaks.

 While the northern Kita Dakay cone last erupted 4850 years ago, the southern Manami Daki and adjacent shooters have since been the site of recent activity. Zooming out, you might note that the Sakurajima volcano is located on a circular ridge in the northern part of Kagoshima Bay. This is not a coincidence, as the northern part of the bay represents the outline of two large calderas. The larger of these calderas is 19 km wide and formed in a super eruption that occurred 290 years ago. That eruption covered much of the island of Kyushu in a thick layer of ash and pyroclastic flow deposits, causing its underlying magma chamber to be largely drained.

 This caused the overlying rock to collapse downwards like a single, forming a massive caldera. In total, that ancient eruption ejected 400 cubic kilometers of volcanic rock, which is around 40 to 60 times larger than the January 2022 eruption of Hangatangahanga Hapai. Thus, since the Kurajima is merely the youngest cone of the broader Iroh caldera, it can accurately be described as a supervolcano that happens to be erupting. It just so happens that its eruptions are generally quite small and are unlikely to collapse into another caldera anytime soon. However, Sakurajima does not need to produce a super eruption to be potentially deadly.

As one of the most dangerous volcanoes on the planet, all that is needed is an unusually energetic explosion that throws car-sized rocks several kilometers away into a major city. Today's earlier explosion represents the first time that large blocks of material were thrown beyond 2500 meters from the active vent. In the 21st century, on prior occasions, such as on November 29, 2013, or on June 4, 2020, smaller centers were thrown to even greater distances, but these were unlikely to destroy any buildings in the next several hours. Today, two things could happen. It is quite possible that this explosion was a one-off event, fed by an unusually gas-rich batch of dying, which means that the volcano will return to its typical lesser level of intensity. Or more similarly, energetic explosions will occur, potentially placing thousands of people at risk.