Resumen de Why Japan megaquake was heard in space
An ultra-thin fault zone packed with slippery clay was behind the massive seismic slip during the devastating Tohoku earthquake of 2011 in Japan. The quake was so great that it changed the region's gravitational field and was "heard" from space. To find out how such a large slip--greater than 50 meters in places--happened, seismologists on board Japan's deep-sea research vessel Chikyu drilled boreholes nearly 850 meters deep into the seabed around the plate boundary that ruptured in 2011. This revealed significant amounts of smectite, a slippery clay largely responsible for many major landslides in Europe. The researchers also found that the fault zone was less than 5 meters thick, tens of times thinner than at other subduction zones, facilitating the slip.
