Japan's strong earthquakes stem from a deep-seated origin

Throughout the previous half-century, Japan has experienced a series of highly powerful earthquakes, the most memorable of which struck in 2008 and 2011. These earthquakes, registering between seven and eight on the Richter scale, likely originate from a source hidden deep beneath the earth's surface. This hypothesis has been proposed in a recent study conducted by scientists at the University of Memphis.

According to the study, the Daiichi-Kashima underwater volcano, situated about 31 miles deep and roughly 25 miles east of the Japanese coast, maybe the culprit behind these earthquakes. This site is unique as it intersects three tectonic plates - the Philippine, Pacific, and Okhotsk plates.

The underwater volcano, located on a descending section of one of these plates, started sinking into the Earth's mantle around 200,000 years ago. Scientists believe that its activity is linked to the 1982, 2008, and 2011 earthquakes – events whose origins were previously unexplained due to the inadequate interactions of the involved tectonic plates.

When underwater volcanoes and mountains move through the subduction plate, they face significant resistance which can cause a blockage. The resulting pressure at the edge of the volcano or mountain eventually forces a shift inward. This culminates in the volcano or mountain breaking free from the plate and jolting forward - a process that triggers opposite vibrations in the plates and subsequently, an earthquake. This plausible mechanism has the backing of scientific research.

The likelihood of further earthquakes induced by Daiichi-Kashima in the foreseeable future remains uncertain, according to the scientists. However, the potential cannot be completely dismissed. Nevertheless, it is believed that other underwater volcanoes and mountains along the Japanese coastline should pose no significant threat for around another two million years.