What type of eruption does Oshima produce?
It is a mostly submerged stratovolcano that forms an 11 x 13 km island. Oshima erupts very frequently, on average every 1-3 years, but has been quiet since 1990, which is an unusual long interval compared to its activity in historic times.
What is the composition of the Oshima volcano?
The volcano, composed mainly of basalt, is between 49.5 and 58.0 wt %.. Miharayama summit A-Crater taken from the northeast on November 17, 1986. Courtesy of Osamu Oshima.
What type of volcano is Oshima volcano?
stratovolcanoes
Oshima-Oshima, a small, 4-km-wide Japan Sea island 55 km west of the SW tip of Hokkaido, is the emergent summit of two coalescing basaltic-to-andesitic stratovolcanoes. Higashiyama, at the east end of the island, is cut by a 2-km-wide caldera covered on its west side by Nishiyama volcano.
Is Oshima volcano active?
The Izu-Oshima volcano is one of the most active volcanoes in Japan, and has generated relatively large-scale eruptions every 30–40 years for the past 200 years. As more than 30 years have passed since the last eruptions in 1986–87, volcanic activity is expected to resume in the near future.
When was Oshimas last eruption?
1990
The last recorded eruption was in 1990. The epicenter of the 1923 Great Kantō earthquake, which devastated Tokyo and the surrounding region, was deep beneath Izu Ōshima Island.
What is the geological area of the Oshima volcano?
Geological Summary Oshima-Oshima, a small, 4-km-wide Japan Sea island 55 km west of the SW tip of Hokkaido, is the emergent summit of two coalescing basaltic-to-andesitic stratovolcanoes. Higashiyama, at the east end of the island, is cut by a 2-km-wide caldera covered on its west side by Nishiyama volcano.
How big is the Oshima volcano in Japan?
Oshima volcano (伊豆大島 Izu-ōshima) is the northernmost of the Izu islands of Japan, and one of the world’s most active volcanoes. It is a mostly submerged stratovolcano that forms an 11 x 13 km island.
How did the Oshima volcano cause a tsunami?
The western cone partially collapsed during an eruption in 1741, creating a large horseshoe-shaped caldera breached to the north and extending from the summit down to the sea floor at the base of the volcano. This event produced a mostly submarine debris avalanche that traveled 16 km distance, and triggered a large tsunami.
Where are the volcanoes in the Japan Sea?
This small island 55 km W of Hokkaido in the Japan Sea consists of two coalescing volcanoes. An eruption in August 1741 produced heavy ashfall on the Hokkaido mainland.
When did the Nishi yama volcano erupt in Japan?
An eruption in August 1741 produced heavy ashfall on the Hokkaido mainland. A violent explosion and landsliding from the Nishi-yama cone accompanied a large tectonic earthquake and a major tsunami that killed 1,475 people, most on the W coast of the Oshima Peninsula.