ccording to public broadcaster NHK, the tsunami alert for the northeast coast has been lifted, about two hours after the quake. Earlier, the workers at the crippled Fukushima Daiichi nuclear plant were warned to evacuate following an alert for a tsunami of 50 centimeters issued by the country's metreological agency. However, there were no immediate reports of damage from the earthquake.
The earthquake struck at 9:57 local time (0057 GMT). The epicenter of the quake was in the Pacific Ocean off the coast of Japan's main island, Honshu, at a depth of about 20 miles (30 kilometers).
Scientists believe that pieces of rock and seafloor from deep in the Pacific Ocean near Costa Rica might be helpful in explaining why Japan's deadly magnitude-9.0 quake was so large. Falling within the so-called Ring of Fire zone, both Japan and Costa Rica nations are prone earthquakes. Volcanic arcs and oceanic trenches partly encircling the Pacific Basin form the Ring of Fire, a zone of frequent earthquakes and volcanic eruptions.
Scientists have collected nearly 1 mile of sediment cores (cylinders of earth drilled out from the ground) from the ocean floor off the coast of Costa Rica, revealing detailed records of about 2 million years of tectonic activity along a nearby seismic plate boundary, where one tectonic plate dives beneath another, called a subduction zone. It was the crack of a subduction zone that generated the Japan quake, Insidecostarica reported.
"It's critical to understand how subduction zone earthquakes and tsunamis originate - especially in light of recent events in Japan," said Rodey Batiza of the National Science Foundation's Division of Ocean Sciences. "The results of this expedition will also help us learn more about our own such zone off the Pacific Northwest." coast,daiichi,earthquake,fukushima,japan,japan earthquake,japon,northeastern,nuclear,plant,s,terremoto en japon,tsu,tsunami,World
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