Long-Period Ground Motions Observed in the Northern Part of Kanto Basin, During the 2011 off the Pacific Coast of Tohoku Earthquake, Japan
Seiji Tsuno*, Andi Muhamad Pramatadie**, Yadab P. Dhakal**,
Kosuke Chimoto**, Wakana Tsutsumi**, and Hiroaki Yamanaka**
*Earthquake Disaster Prevention, Railway Technical Research Institute, 2-8-38 Hikari-cho, Kokubunji-shi, Tokyo 185-5840, Japan
**Department of Environmental Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8502, Japan
During the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0), strong ground motions were observed at many seismic stations in the Tokyo Metropolitan Area located about 200 km away from the southern edge of the earthquake source fault. Large earthquake responses in high-rise buildings having long natural periods of several seconds were also observed. The largest ground responses for a period of 4 to 5 seconds were observed locally in Oyama (K-NET TCG012) and Koga (K-NET IBR009) on the border between Tochigi and Ibaraki Prefectures in the northern part of Kanto basin. Geophysical information in these areas was not accurate enough, however, to evaluate these ground motions. To understand S-wave velocity structures, we performed array microtremors observations at TCG012 seismic station in Oyama. We applied the Spatial Autocorrelation (SPAC) method to array microtremors data for vertical components. Rayleigh wave phase velocity from 0.3 to 1.6 km/s was obtained for a period of 0.25 to 3 seconds. We inverted phase velocity to a S-wave velocity structure reaching to bedrock at a depth of 1.6 km, using a Genetic Algorithm. The estimated structure explained the first peak of the H/V spectral ratio of microtremors well by the ellipticity of fundamentalmode Rayleigh wave. To evaluate long-period ground motions observed around Oyama during the main shock, we estimated earthquake ground motions by 1-D analysis, showing agreements with and the differences from those observed. As a result, velocity calculated at IBR008 located midway between the Tsukuba Mountains and Oyama, explained that observed for main phases and later phases. However, velocity calculated at TCG012 did not explain that observed for later phases. According to the emphasis of airy phases for group velocity of Love wave using the estimated S-wave velocity structure and the principal axis for later phases obtained by PCA corresponding to the vibration direction of Love wave propagating from the earthquake source fault and through the Tsukuba Mountains, long-period ground motions of a period of 3 to 5 seconds observed at TCG012 lasting for 200 seconds after the arrival of main phases, consist of Love wave.
Kosuke Chimoto, Wakana Tsutsumi, and Hiroaki Yamanaka, “Long-Period Ground Motions Observed in the Northern Part of Kanto Basin, During the 2011 off the Pacific Coast of Tohoku Earthquake, Japan,” J. Disaster Res., Vol.8, No.sp, pp. 781-791, 2013.
-  Y. Yokota, K. Koketsu, Y. Fujii, K. Satake, S. Sakai, M. Shinohara, and T. Kanazawa, “Joint Inversion of Strong Motion, Teleseismic, Geodetic, and Tsunami Datasets for the Rupture Process of the 2011 Tohoku Earthquake,” Geophys. Res. Lett., Vol.38, L00G21, doi:10.1029/2011GL050098, 2011.
-  W. Suzuki, S. Aoi, H. Sekiguchi, and T. Kunugi, “Source Rupture Process of the 2011 off the Pacific Coast of Tohoku Earthquake Derived from Strong-Motion Records,” Research Report on the 2011 Great East Japan Earthquake Disaster, Natural Disaster Research Report, Vol.48, pp. 53-62, 2012 (in Japanese).
-  S. Tsuno, H. Yamanaka, S. Midorikawa, S. Yamamoto, H. Miura, S. Sakai, N. Hirata, K. Kasahara, H. Kimura, and T. Aketagawa, “Characteristics of Long-Period Ground Motions in the Tokyo Metropolitan Area and its Vicinity, by Recording Data of the 2011 off the Pacific Coast of Tohoku Earthquake (Mw9.0) and the Aftershocks,” Journal of JAEE, Vol.12, No.5, pp. 102-116, 2012a (in Japanese).
-  T. Kubo, Y. Hisada, K. Aizawa, K. Omiya, and S. Koizumi, “Investigation of Indoor Damage and Questionnaire Intensity for High-Rise Building in Tokyo during Great East Japan Earthquake,” Journal of JAEE, Vol.12, No. 5, pp. 1-20, 2012 (in Japanese).
-  M. Nagano, T. Hida, K. Watanabe, T. Tanuma, M. Nakamura, N. Ikawa, M. Yasui, S. Sakai, T. Morishita, and M. Kawashima, “Dynamic Characteristics of Super High-Rise Residential Buildings in Kanto and Kansai Area Based on Strong Motion Records during the 2011 off the Pacific Coast of Tohoku Earthquake,” Journal of JAEE, Vol.12, No.4, pp. 65-79, 2012 (in Japanese).
-  S. Tsuno, H. Yamanaka, S. Midorikawa, S. Sakai, N. Hirata, H. Miyake, and K. Koketsu, “Long-Period Earthquake Ground Motions Observed in the Kanto Basin,” Proceedings of the 4th Symposium of Earthquake Ground Motion, Architectural Institute of Japan, pp. 4550, 2012b (in Japanese).
-  H. Kawase, “Review: Amplification of SeismicWaves by Sedimentary Layers and its Simulation,” Jishin, Vol.2, No.46, pp. 171-190, 1993 (in Japanese).
-  H. Kawase and Y. Hayashi, “Strong Motion Simulation in Chuo Ward, Kobe, during the Hyogo-Ken Nambu Earthquake of 1995 Based on the Inverted Bedrock Motion,” Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.480, pp. 67-76, 1996 (in Japanese).
-  A. Pitarka and K. Irikura, “Basin Structure Effects on Long Period Strong Motions in the San Fernando Valley and the Los Angeles Basin from the 1994 Northridge Earthquake and an Aftershock,” Bull. Seism. Soc. Am., Vol.86, S126-S137, 1996.
-  K. Afnimar, K. Koketsu, and K. Nakagawa, “Joint Inversion of Refraction and Gravity Data for the Three-Dimensional Topography of a Sediment-Basement Interface,” Geophys. J. Int., Vol.151, pp. 243-254, 2002.
-  H. Yamanaka and N. Yamada, “Estimation of 3D S-wave Velocity Model of Deep Sedimentary Layers in Kanto Plain, Japan, using Microtremor Array Measurements,” BUTSURI-TANSA, Vol.55, No.1, pp. 53-65, 2002 (in Japanese).
-  H. Yamanaka and N. Yamada, “Modeling 3D S-wave Velocity Structure of Kanto Basin for Estimation of Earthquake Ground Motion,” BUTSURI-TANSA, Vol.59, No.6, pp. 549-560, 2006 (in Japanese).
-  National Research Institute for Earth Science and Disaster Prevention, “Report on Development of an Integrated Geophysical and Geological Information Database,” Technical Note of the NIED, Vol.361, 2011 (in Japanese).
-  P. Y. Dhakal, H. Yamanaka, and T. Sasatani, “Tuning the Deep Velocity Structure Model of the Tokyo Metropolitan Area Based on 1-D Simulation of Long-Period S-wave,” Proceedings of the 4tth IASPEI/IAEE International Symposium: Effects of Surface Geology on Seismic Motion, Paper ID 3.5, 2011a.
-  P. Y. Dhakal and H. Yamanaka, “Validation of the Deep Velocity Structure Model of the North-West Region of the Kanto Basin Using Long-Period S-waves from Moderate Earthquakes,” Proceedings of the 10th SEGJ International Symposium – Imaging and Interpretation –, pp. 392-395, 2011b.
-  S. Sakai and N. Hirata, “Distribution of the Metropolitan Seismic Observation Network,” Bull. Earthq. Res. Inst. Univ. Tokyo, Vol.84, pp. 57-69, 2009.
-  K. Kasahara, S. Sakai, Y. Morita, N. Hirata, H. Tsuruoka, S. Nakagawa, K. Nanjo, and K. Obara, “Development of the Metropolitan Seismic Observation Network (MeSO-net) for Detection of Mega-Thrust beneath Tokyo Metropolitan Area,” Bull. Earthq. Res. Inst. Univ. Tokyo, Vol.84, pp. 71-88, 2009.
-  K. Kudo, M. Takahashi, M. Sakaue, T. Kanno, H. Kakuma, and D. Tsuboi, “A Highly Over-Damped Moving Coil Type Accelerometer for Mobile Strong Motion Observation and its Performance Tests,” Report of Grant-in-Aid for Scientific Research-07558056, 1998 (in Japanese).
-  K. Aki, “Space and Time Spectra of Stationary Stochastic Waves, with Special Reference to Microtremors,” Bull. Earthq. Res. Inst., Vol.35, pp. 415-456, 1957.
-  H. Okada, “The Microtremors Survey Method,” Geophysical Monograph Series Society of Exploration Geophysicists, 2003.
-  H. Yamanaka and H. Ishida, “Application of Genetic Algorithms to an Inversion of Surface-Wave Dispersion Data,” Bull. Seism. Soc. Am., Vol.86, No.2, pp. 436-444, 1996.
-  W. J. Ludwig, J. E. Nafe, and C. L. Drake, “Seismic Refraction,” The Sea, Vol.4, Edited by A. E. Maxwell, Wiley Interscience, New York, pp. 53-84, 1970.
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