Volcanic Activity Suspected as Cause of Recent Earthquake and Tsunami off Japan
Tokyo, Japan – A recent earthquake and subsequent tsunami that struck off the coast ofJapan on September 24th are believed to be linked to volcanic activity near the epicenter, according to experts.
The earthquake, registering around magnitude 6on the Richter scale, occurred near the underwater volcano known as Sumisu-jima, located in the Izu-Ogasawara Islands. OsamuSanbata, an assistant professor at the Earthquake Research Institute of the University of Tokyo, has pointed to a phenomenon known as 陥窓断層破裂 (Kan’ō Dan’sō Haretsu), or trapdoor fault rupture, as the likely cause.
Sanbata explained that Sumisu-jima has a history of experiencing similar earthquakes, roughly every 10 years. These earthquakes are often accompanied by tsunamis, which are believed to be triggered by thetrapdoor fault rupture mechanism. This process involves the upward movement of magma from beneath the Earth’s crust, creating a bulge on the seabed.
The trapdoor fault rupture occurs at a shallower depth than typical earthquakes, resulting in less intense shaking felt on land. However, the sudden change inseabed topography can generate significant tsunamis.
The trapdoor fault rupture mechanism is distinct from typical earthquakes, Sanbata emphasized. While the shaking is less intense, the resulting seabed deformation can be substantial, leading to powerful tsunamis.
Following the earthquake, the Japan Meteorological Agency (JMA)observed a change in the water color around Sumisu-jima, indicating potential volcanic activity. As a precaution, the JMA issued a volcanic eruption alert for the surrounding waters, urging vessels to exercise caution.
Sanbata further explained that while trapdoor fault ruptures often lead to a period of calm inunderground activity, the accumulation of magma beneath the surface could eventually lead to other volcanic phenomena.
There is a possibility that the magma buildup could trigger a volcanic eruption, which in turn could generate another tsunami, Sanbata cautioned. It is crucial to monitor the ongoing underground activity closely.
The JMA isclosely monitoring the situation and will continue to assess the risks posed by potential volcanic eruptions and subsequent tsunamis. The agency has urged the public to remain vigilant and stay informed about the latest developments.
This event serves as a reminder of the dynamic nature of the Earth’s crust and the potential hazards associated with volcanicactivity. While the immediate threat from the recent earthquake and tsunami has subsided, the possibility of further volcanic activity remains a concern for the region.
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