Increased seismicity, eruption alert level raised for Tsurumidake and Garandake, Japan

southwest side of mount yufu japan bg

The Japan Meteorological Agency (JMA) raised the alert level for Tsurumidake and Garandake, Kyushu, Japan on July 8, 2022, from 1 to 2 (restriction on proximity to the crater). The last eruption at this volcano took place in the year 867 (VEI 3).

The number of earthquakes at the volcano rose sharply on July 8, with up to 90 shallow earthquakes at depths between 1 and 4 km (0.6 – 2.5 miles) east of the Garandake dome.

As a result, JMA raised the alert level to 2, urging residents not to approach within 1 km (0.6 miles) from Tsurumidake and Garandake.1

The agency warned of possible eruptions at the Garandake crater with potential pyroclastic flows within 1 km (0.6 miles) of the crater.

Local authorities have stopped the Beppu Ropeway, evacuated Tsukahara Onsen, and closed Prefectural Road 616 near the volcanoes.2

An eruption could cause localized transport disruptions and flight delays at Oita Airport (OIT) in case there is a significant ash plume.

southwest side of mount yufu japan bg
Southwest side Mount Yufu. Credit: TakaSunrise091

Geological summary

A group of lava domes rises above the noted hot spring resort city of Beppu on Japan’s Inland Sea, possibly within an ancient breached caldera.

Two large lava domes, Tsurumidake and Yufudake (the highest at 1 584 m / 5 196 feet), are located at the east and west sides of the Yufu-Tsurumi complex, respectively.

Three smaller lava domes are on the N flank of Tsurumidake, including Garandake.

The latest activity at both the andesitic-to-dacitic Tsurumi and Yufu groups postdates the 6 300-year-old Akahoya ash from Kikai volcano.

Pyroclastic flows dominated during older eruptions, whereas lava domes and lava flows are most common in more recent eruptions.

An eruption about 2 200 years ago from Yufudake began with collapse of the N flank that produced a debris avalanche and was followed by lava dome growth and associated pyroclastic flows.

Only a single eruption, from Tsurumi in 867 CE, is known in historical time.

The colorful hot spring pools and mudpots of Beppu along the coast form one of Japan’s most noted thermal areas.3


1 Volcanic Warnings: Tsurumidake and Garandake Volcanic Warning (Near the crater) – JMA – July 8, 2022

2 Japan: Officials increase warning level at Mount Tsurumi and Garandake volcanoes in Oita Prefecture as of early July 8 – Garda – July 8, 2022

3 Yufu-Tsurumi – Geological summary – GVP

Featured image: Southwest side Mount Yufu. Credit: TakaSunrise091


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