The 2011 Tohoku earthquake. (a) The source region of the 2011 Tohoku earthquake. Thick black curves are plate boundaries and the arrows show the relative plate motions. The mainshock (yellow star) and earthquakes with M ≥5.0 occurred within a week (yellow circles). Blue arrows are coseismic movements of land-based GPS stations  and black arrows are marine GPS/acoustic measurements . The white contours show the slip distribution with 4 m interval estimated from the tsunami waveforms . The red triangles show the locations of the bottom pressure (TM1), GPS wave and coastal tide gauges. The proposed fault models (orange rectangles) of the 1896 Sanriku tsunami earthquake  and the 869 Jogan earthquake  are shown. Black star shows the location of Fukushima Dai-ichi Nuclear Power Station. (b) The tsunami waveforms recorded by the bottom pressure gauge (TM1), GPS wave gauge and coastal tide gauge .