Presentation information


Joint Symposia » J08. Imaging and interpreting lithospheric structures using seismic and geodetic approaches

[J08-P] Poster

Fri. Aug 4, 2017 3:00 PM - 4:00 PM Shinsho Hall (The KOBE Chamber of Commerce and Industry, 3F)

3:00 PM - 4:00 PM

[J08-P-02] Waveform inversion to image laterally inhomogeneous crustal structure - comparison among waveform inversion, traveltime inversion, and seismic migration -

Takeshi Sato1, Gou Fujie1, Kazuya Shiraishi1, Shuichi Kodaira1, Seiichi Miura1, Eiichi Asakawa2, Takao Nibe2, Norimitsu Yui2, Susumu Abe3, Romain Brossier4, Jean Virieux4 (1.JAMSTEC, Yokohama, Japan, 2.JGI Inc., Tokyo, Japan, 3.JAPEX, Tokyo, Japan, 4.University Grenoble Alpes, Grenoble, France)

High-resolution seismic velocity structure in geologically complex areas is of crucial importance for the understanding of evolution and formation processes associated with plate tectonics. However, it was difficult to image laterally inhomogeneous structural features such as sub-vertical intrusions into the crust by seismic migration of multi-channel seismic reflection (MCS) data or by traveltime analysis of ocean bottom seismographs (OBSs) using controlled sources. On one hand, migration has difficulties for imaging steep reflectors and, on the other hand, the spatial resolution of the traveltime analysis is low, especially when considering first-arrivals. Alternatively, full waveform inversion (FWI) is a promizing technique for an improved quantitative detailed seismic structure even in geologically complex area because full wave propagation is performed for honoring recorded traces.
In the fore-arc region of the Izu-Bonin island arc, Tatsumi and Stern (2006) suggested a sub-vertical intrusion of the middle crust below the Eocene paleo arc. For assessing the existence of such intrusive structural feature, we conducted MCS survey and wide-angle OBS-airgun survey (OBS deployed 1 km interval) in this region (Yamashita et al., 2009). We applied pre-stack depth migration to the MCS data, but we could not image the intrusive feature. On the contrary, we attempted to apply FWI to this wide-angle OBSs dataset and we succeeded in imaging this intrusive feature. From these results, we may deduce that the FWI is an effective tool for detecting steep tectonic structures such as sub-vertical intrusion.