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Fig. 1. | Earth, Planets and Space

Fig. 1.

From: Rapid source characterization of the 2011 Mw 9.0 off the Pacific coast of Tohoku Earthquake

Fig. 1.

Map of the tectonic setting of the March 2011 Tohoku Earthquake. The large maroon circle is the USGS NEIC epicenter of the mainshock; red dots with gray outlines are aftershocks, through the end of April 2011. White circles with gray outlines represent seismicity prior to March 9th 2011. Dark gray circles with red outlines represent foreshocks of the Tohoku event, beginning with the Mw 7.3 March 9th earthquake. All circles have radii scaled according to each earthquakes magnitude. Light gray focal mechanisms are gCMT (http://www.globalcmt.org) solutions of aftershocks, plotted at the equivalent USGS NEIC locations. Dark gray dashed lines represent the depth of the subducting Pacific slab, from Slab1.0 (http://www.earthquake.usgs.gov/research/data/slab), in 20 km intervals. The thick transparent white line represents the major plate boundary. Inset shows the USGS W-phase CMT solutions for the mainshock and 03/09 foreshock. Part (b) shows a cross-section of the subduction zone through the hypocenter of the mainshock (gray star), overlain with a 2D profile through Slab1.0. Yellow CMTs are gCMT solutions used to constrain the slab geometry; gray circles represent background seismicity. Red diamonds represent data from local active seismic surveys, also used to constrain geometry. See URL (above) for more details. The lower panel shows the dip of the Slab1.0 interface.

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