Japan issues first ‘megaquake’ warning for Nankai Trough after strong temblor
TOKYO – A 7.1-magnitude earthquake struck off the coast of Miyazaki prefecture on the southern Japanese island of Kyushu on Thursday, the Japan Meteorological Agency said, prompting it to issue a tsunami alert as well as its first warning for a “megaquake” from a nearby submarine trough that is a hotbed of geological tension.
Although the expected height of the tsunami is only about 3.3 feet, the waves can grow exponentially quickly, the JMA said. The quake hit at a depth of 18.6 miles, the agency said.
Chief Cabinet Secretary Yoshimasa Hayashi said at a news conference that there have been no reports of abnormalities at nuclear power plants after the quake and that the government is assessing for casualties and damage. Japan Rail suspended bullet train services as a precaution, state broadcaster NHK reported. No casualties or major damage were immediately reported after the quake.
The JMA issued its first public warning for a “Nankai Trough megaquake” after an investigation into the Thursday quake’s links to the submarine trough. The agency said the chance of a major earthquake there that could trigger powerful tsunamis is “relatively higher than usual for the next week.”
Earthquakes typically occur in the Nankai Trough every 100 to 150 years, according to the JMA. The most recent was in December 1946, when a quake of around 8.1 in magnitude killed more than 1,300 people. The U.S. Geological Survey notes that with more than 36,000 houses were destroyed or severely damaged and another 2,100 homes were washed away by a tsunami that reached heights of 16 to 20 feet.
In January, Japan’s Earthquake Research Committee predicted a 70 to 80% chance of an earthquake between 8.0 and 9.0 in magnitude striking near the Nankai Trough within the next three decades.
While Japan is familiar with earthquakes – the country sits on the Pacific Ring of Fire – large tremors on the coast cause particular alarm because of their propensity to cause tsunamis. Japan experiences about 1,500 earthquakes annually that can be felt by people, with some kind of seismic activity recorded once every 5 minutes.
Memories of the 9.0-magnitude earthquake that struck the Tohoku region on Japan’s east coast in 2011, causing a devastating tsunami that claimed almost 20,000 lives, remain raw in Japan.
The quake and tsunami also caused the meltdown of three reactors at the Fukushima Daiichi nuclear plant.
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Masih reported from London.
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Graphic: https://washingtonpost.com/documents/bdacca36-ef0f-460d-85eb-3d8e046bf313.pdf