Expert: Underground fluids likely factor in Japan's Noto Peninsula quakes

A Japanese expert says strong earthquakes and tsunami could strike the Noto Peninsula on the Sea of Japan coast due to migration of fluids trapped underground.

Last Friday's magnitude-6.5 quake registered upper 6 on the Japanese seismic scale from zero to seven in the city of Suzu, Ishikawa Prefecture. The city is located on the northern tip of the peninsula.

As of 4 p.m. on Friday, swarm quakes registering one or higher on the Japanese scale had hit the region 95 times since about a week ago.

Professor Nakajima Junichi of the Tokyo Institute of Technology analyzed small tremors, which people cannot feel, in the peninsula and surrounding areas for a period of 18 years through 2020.

The analysis estimated that a large volume of fluids, such as water, had accumulated in wide areas at depths of 20 to 40 kilometers.

Nakajima believes that those fluids, which would make it easier for underground faults to migrate, could be responsible for frequent seismic activities in the region. He also believes that such activities will unlikely be lessen anytime soon as the fluids are spreading.

Nakajima notes that seismic activities were centered in inland areas on the peninsula before the May 5 quake, but that the activities now appear to be stretching north.

He says that if a magnitude 7-class quake hits waters north of the peninsula where multiple active faults exist, it could generate tsunami. He advises residents in the coastal region to evacuate to higher ground in case of a strong earthquake.