why does japan experience so many earthquakes and tsunamis

A magnitude-7. 0 earthquake struck southern Japan today, less than two days after a 6. 2-magnitude temblor rocked the same region, triggering tsunami advisories in the area. The most recent earthquake struck the Kumamoto region on Japan s Kyushu Island early Saturday (April 16) at 1:25 a. m. local time (12:25 p. m. ET on April 15),
(USGS). The smaller 6. 2-magnitude quake on Thursday (April 14) killed nine people and injured hundreds more,. With residents of the Kumamoto region reeling from two sizable earthquakes in as many days, and with memories of the that devastated Tohoku, Japan, in 2011 not far from people s minds, what is it about this part of the world that makes it so seismically active? [ For starters, Japan is located along the so-called, which is the most active earthquake belt in the world. This ring is actually an imaginary horseshoe-shaped zone that follows the rim of the Pacific Ocean, where many of the world s earthquakes and volcanic eruptions occur. Within the Ring of Fire, several tectonic plates including the Pacific Plate beneath the Pacific Ocean and the Philippine Sea Plate mash and collide. The Earth s surface is broken up into about a dozen or so major chunks that are all moving around. Where they all interact at their edges, interesting things happen, said Douglas Given, a geophysicist with the USGS in Pasadena, California.


Today s earthquake seems to have been caused by the Philippines Sea Plate diving underneath the Eurasia Plate, according to Paul Caruso, a geophysicist with the USGS. While Japan is no stranger to earthquakes, the 7. 0-magnitude temblor is one of the largest ever recorded in this part of southern Japan, Caruso told Live Science. The second-largest was probably on March 20, 1939 there was a magnitude-6. 7 in this area. And we ve had magnitude-6. 5 and magnitude-6. 3 earthquakes, but this is the largest quake that has been measured in that vicinity, he said. A tsunami advisory was issued after today s earthquake, but it was subsequently lifted by the Japan Meteorological Agency, and there are currently no major in effect. Not all earthquakes trigger tsunamis, Caruso said. In general, there are three key ingredients that can produce a dangerous earthquake-tsunami combination, he added. First, the earthquake must be at least a magnitude-7 temblor. Second, the quake s epicenter has to be underneath the ocean, Caruso said. And finally, the earthquake has to be shallow. We have quakes around Fiji all the time, but those are sometimes 400 miles [640 kilometers] underground, so they, he said. Today s earthquake was shallow about 6 miles (10 km) underground but the epicenter was on land, meaning there aren t likely to be any dangerous tsunamis as a result, Caruso said.


Given said he hasn t seen many damage reports yet, but Japanese authorities and scientists at the USGS will be monitoring the area for potentially dangerous aftershocks, which are smaller quakes that follow the largest event in a series and that generally decrease in strength. This seems to be a pretty energetic sequence, and there are lots of large aftershocks, Given told Live Science. And of course, after a large earthquake, structures are often weakened as a result. Additional damage can be expected. Residents of the area should expect more shaking in the coming days, according to Caruso. We can say for certain that there are going to be more aftershocks in this area, he said. Exactly when and how big they re going to be is difficult to say, though. No one can predict that. Follow Denise Chow on Twitter @denisechow. Follow Live Science @livescience, Facebook Google+. Original article on. A magnitude-6. 9 earthquake struck yesterday off the coast of Fukushima, Japan, likely along the same fault that ruptured in 2011, unleashing a massive 9. 0-magnitude temblor that triggered deadly tsunamis and caused widespread destruction. Over the course of its history, Japan has seen its share of shaking, but what makes this part of the world so susceptible to big earthquakes?


The answer has to do with Japan s location. The island nation lies along the so-called Pacific Ring of Fire, an imaginary horseshoe-shaped zone that follows the rim of the Pacific Ocean, where many of the world s earthquakes and volcanic eruptions occur. In fact, 81 percent of the world s largest earthquakes happen in this active belt, according to the U. S. Geological Survey (USGS). [ The Earth s surface is broken up into about a dozen or so major chunks that are all moving around. Where they all interact at their edges, interesting things happen, Douglas Given, a geophysicist with the USGS in Pasadena, California,. Within the Pacific Ring of Fire, several tectonic plates mash and collide. In what are known as, one plate bends and slides underneath the other, causing the oceanic crust to sink into the Earth s mantle. From Alaska down to Japan and the Philippines, all the way down around the western Pacific and then the boundary of the west coast of South America and central America are all big subduction zones, said Robert Smith, an emeritus professor of geophysics at the University of Utah. Japan itself sits atop a complex mosaic of that grind together and trigger deadly earthquakes and volcanic eruptions, Smith told Live Science.


Yesterday s earthquake off the coast of Fukushima was centered about 80 miles (130 kilometers) southwest of the epicenter of the 9. 0-magnitude Tohoku quake that struck in March 2011. This means the magnitude-6. 9 temblor, according to seismologists. There s been a whole sequence [of aftershocks] since the 2011 earthquake, Smith said. These enormously big earthquakes have aftershocks that can continue for tens to hundreds of years. It s very common. The 2011 earthquake released hundreds of years of pent-up stress within the subduction zone and triggered an enormous tsunami that inundated the coastal Fukushima Daiichi Nuclear Power Plant, eventually causing a level 7 nuclear meltdown. While yesterday s quake was not as powerful as the Tohoku temblor, the entire region is still at risk of big earthquakes. The Tohoku quake was one of the biggest earthquakes we ve recorded historically, but the fact is, the seismic hazard of the whole subduction zone is extremely high, so large earthquakes are more common there than other places, Smith said. Earlier this year, in April, a magnitude-7. 0 earthquake struck the Kumamoto region in southern Japan, two days after a 6. 2-magnitude temblor shook the same area. Original article on.

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