[S-IT19] Deep Earth Sciences

[SIT19-06] Multifrequency P-wave tomography of Honshu slab

*Masayuki Obayashi¹, Junko Yoshimitsu¹, Hitoshi Kawakatsu², Masanao Shinohara² (1.Japan Agency for Marine-Earth Science and Technology, 2.Earthquake Research Institute, The University of Tokyo)

Keywords:slab, sub-slab, tomography

We obtained a three dimensional P-wave velocity structure with a focus on the Honshu slab and its surrounding sub-slab mantle using data from ocean bottom seismometers (OBSs) that were temporally deployed off the coast of northeast Japan. We also collected Hi-net data during the same periods of the OBS. We measured more than ~5 million relative travel times of P-wave between any two stations using the cross-correlation method, in passbands between 21.2 s and 1.3 s dominant period. We inverted these data in addition to more than 30 million first arrival data of International Seismological Centre using the multifrequency tomography technique. Figure shows the obtained results of P-wave velocity anomalies at depths of approximately 45, 58, 85 and 120 km in comparison with the results from ISC data only. Some characteristics become pronounced by adding the OBS and Hi-net data; a gap in the fast anomalies of the subducting Honshu slab (black arrow), slow anomalies oceanward of the slab (white arrow). The results will be discussed with the resolution of the model in the presentation.