Fig. 2
From: Transition from collision to subduction and its relation to slab seismicity and plate coupling
Observed seismic records and their comparison with synthetic seismograms. a Observed seismograms of SP-W1 to which a 1–15-Hz band-pass filter is applied. Red arrow highlights reflected waves from plate boundary (PB). Each trace is normalized by its maximum amplitude. b Synthetic seismograms for SP-W1 calculated from velocity model of (c) in which a thin low-velocity (3.0 km/s) layer atop the slab is assumed. c Ray diagrams of SP-W1 for the reflected waves from the plate boundary (black curves). Numerical values in the plot are P wave velocities estimated from first arrival times. For deeper parts (in parentheses), we assumed velocities using the surrounding experiments (Arai et al. 2009, 2013; Arai and Iwasaki 2014). Note that this reflective zone is located at the down-dip end of the strongly coupled plate boundary (see also Fig. 4). d Observed seismograms of SP-E4. e Synthetic seismograms calculated from velocity model of (f) in which a thin low-velocity (2.0 km/s) layer atop the slab is assumed. f Ray diagrams of SP-E4 for the reflected waves from the plate boundary (black curves)