No tsunami, but 7.8 magnitude quake off Japan rattles Tokyo

A massive earthquake that struck off the Japanese coast Saturday evening does not appear to pose a tsunami threat, but it rattled dwellers in Tokyo and others in the Pacific Rim, where seismic activity has been more jumpy than usual recently.

The U.S. Geological Survey reported the quake was of 7.8 magnitude and said it struck about 543 miles south of Tokyo in the Pacific Ocean, near Japan’s Ogasawara Islands. The Pacific Tsunami Warning Center said the earthquake had a magnitude of 8.5 and was at a deep depth of 696 kilometres, or 432 miles.

“There is no tsunami threat because the earthquake is located too deep inside the earth,” said the warning center, a division of the NOAA’s National Weather Service.

Tokyo residents were quick to note on Twitter that, had the quake been at more shallow depth, it could have generated a tsunami possibly worse that the one that struck Japan in 2011, killing more than 15,000 people and triggering a nuclear power disaster.

As it was, Saturday’s quake caused buildings to sway in Tokyo but it only caused minor damage in shops and private homes. Still, many Japanese residents were rattled, partly because of memories of 2011 but also because of a volcano that erupted in the far southern part of Japan on Friday.

“That #earthquake was M8.5 at 590 km depth,” tweeted Mathew Salter, a science publisher based in Tokyo, quoting initial estimates of the tremblor’s depth. “Much shallower and we’d all be dead.”

Friday’s volcano eruption on the island of Kuchinoerabu launched a column of ash high into the air and prompted authorities to order evacuations. There were no reports of injuries but it served as yet another reminder that Japan, the world’s third largest economy, sits amid a particularly active portion of the Pacific Rim’s “ring of fire.”

On Thursday night, a 6.7-magnitude earthquake struck off the coast of the Alaska peninsula at a depth of 35 miles. The quake was felt throughout southwest and south central Alaska but, as forecasters predicted within minutes, it did not trigger a tsunami.