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A proposal for a standard procedure of modeling 3-D velocity structures and its application to the Tokyo metropolitan area, Japan
Koketsu K.a, Miyake H.a, Afnimarb, Tanaka Y.a
a Earthquake Research Institute, University of Tokyo, Japan
b Department of Geophysics and Meteorology, Bandung Institute of Technology, Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]Most metropolitan areas are located over large-scale sedimentary basins. Since the sediments filling basins amplify ground motions and their velocity structures complicate the propagation of seismic waves, it is important for the prediction of strong ground motion and seismic hazard to determine the three-dimensional (3-D) velocity structures of these urban basins. This importance motivated various organizations to carry out extensive geophysical experiments and geological investigations, and velocity structure models are being constructed all over Japan. However, a study of a single dataset cannot completely define a 3-D velocity structure, so that we propose a standard procedure for modeling the 3-D velocity structure of an urban basin in Japan, by simultaneously and sequentially using various kinds of datasets such as those from refraction/reflection experiments, gravity surveys, surface geology, borehole logging, microtremor surveys, and earthquake records. We then apply the procedure to the Tokyo metropolitan area (TMA) over the Kanto basin with an area of about 17,000 km2 and the maximum thickness of about 4 km. As one of the steps in the procedure, a joint inversion of refraction and gravity data has been formulated to determine the 3-D topography of interfaces of the sedimentary layers as well and lateral distribution of the basement slowness. We validate the constructed velocity structure model by comparison of observed and synthetic waveforms, since this modeling is carried out mainly for strong ground motion prediction. The proposed procedure including the joint inversion and validation with ground motion simulations works well for TMA, and the applicability of the standard procedure has been confirmed for regions with substantial data of experiments and earthquake records in Japan. © 2008 Elsevier B.V. All rights reserved.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]3-D velocity structure,Ground motion simulation,Joint inversion,Modeling procedure,Sedimentary basin,Tokyo metropolitan area[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text]3-D velocity structure,Ground motion simulation,Joint inversion,Modeling procedure,Sedimentary basin,Tokyo metropolitan area[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]We thank Shuhei Okubo for his kind suggestions and discussions on gravity anomalies. Masao Komazawa kindly provided us with the gravity data. Thoughtful comments by Tom Brocher, Michael Behm, and the guest editors greatly improved the manuscript. This research was supported by the Japan Science and Technology Corporation under the ACT-JST program 13C-2, the DaiDaiToku Project I of the MEXT, Japan, and the Integrated Velocity Structures Database Project sponsored by the Special Coordination Funds for Promoting Science and Technology.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1016/j.tecto.2008.05.037[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]