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Progress in Earth and Planetary Science
Fig. 2 | Progress in Earth and Planetary Science

Fig. 2

From: Fault geometry of M6-class normal-faulting earthquakes in the outer trench slope of Japan Trench from ocean bottom seismograph observations

Fig. 2

Hypocenter distributions and focal mechanisms based on the tomographic analysis. a Map showing the hypocenters with location errors less than 5 km. Three M6-class earthquakes and others are indicated by stars and circles, respectively. The symbols are color-coded by hypocenter depth. Inverted triangles indicate the OBS locations. b Hypocenter distribution projected along the profile is indicated by thick solid lines on panel (a). Dashed black lines indicate the top of the oceanic crust (Ito et al. 2005) and the approximate depth of the Moho, which is 7 km below the seafloor seaward of the trench and 6 km below the top of the oceanic crust landward of the trench. Inverted triangles indicate the projected locations of OBSs. c Focal mechanisms estimated from first-motion polarities observed by the OBSs. Focal mechanisms are color-coded according to the triangle diagram of Frohlich (1992), as presented in the inset panel. d Focal mechanisms projected along the profile indicated by the thick solid line on panel (c)

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