Finite-Difference Simulation of Long-Period Ground Motion for the Nankai Trough Megathrust Earthquakes
Takahiro Maeda, Nobuyuki Morikawa, Asako Iwaki,
Shin Aoi, and Hiroyuki Fujiwara
National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki 305-0006, Japan
We evaluated long-period ground motions for the anticipated Nankai Trough megathrust earthquake in southwest Japan. To understand a variation of longperiod ground motions caused by the uncertainty of the source model, we performed a finite difference simulation using 104 source models, assuming various possible source parameters, including rupture area, asperity configuration, and hypocenter location. For the variety of rupture areas, we included scenarios that have extremely huge rupture areas, as was proposed by the Japan Central Disaster Management Council of Cabinet Office after the 2011 Tohoku-Oki earthquake. We also included scenarios that have large slip areas near the trough following the lessons learned from the 2011 event. Simulated waveforms and response spectra show a large variation at a site. However, by grouping the simulation results with respect to the source area, we determined that scenarios with wider rupture areas have a larger peak ground velocity and velocity response than those with smaller rupture areas. The influence of the large slip near the trough causes later phases to be large and long. However, the later phases are decreased by using a boxcarlike slip velocity time function instead of a Kostrovlike function and by decreasing rupture velocity. The spatial distribution of the simulated peak ground velocity and velocity response show that the long-period ground motions are amplified particularly on sedimentary basins, where big cities have been established. It is important to consider how to account for the large variation of the simulation results in the seismic hazard assessment.
Shin Aoi, and Hiroyuki Fujiwara, “Finite-Difference Simulation of Long-Period Ground Motion for the Nankai Trough Megathrust Earthquakes,” J. Disaster Res., Vol.8, No.5, pp. 912-925, 2013.
-  K. Ishibashi, “Status of historical seismology in Japan,” Ann. Geophys., Vol.47, pp. 339-368, 2004.
-  Earthquake Research Committee, “On the long-term evaluation of earthquakes in the Nankai Trough (2nd edition),” 2013 (in Japanese),
http://www.jishin.go.jp/main/chousa/13may_nankai/index.htm [accessed September 23, 2013]
-  Earthquake Research Committee, “Long-period grond motion hazard maps for Japan,” 2009 (in Japanese),
http://www.jishin.go.jp/main/chousa/09_choshuki/index.htm [accessed September 23, 2013]
-  Earthquake Research Committee, “Long-period grond motion hazard maps for Japan,” 2012 (in Japanese),
http://www.jishin.go.jp/main/chousa/12_choshuki/index.htm [accessed September 23, 2013]
-  Earthquake Research Committee, “On the strong ground motion evaluation of earthquakes in the Nankai Trough,” 2001 (in Japanese),
http://www.jishin.go.jp/main/kyoshindo/01b/index.htm [accessed September 23, 2013]
-  K. Irikura and H. Miyake, “Prediction of strong ground motions for scenario earthquakes,” Journal of Geography, Vol.110, pp. 849-875, 2001 (in Japanese with English abstract).
-  Earthquake Research Committee, “Strong Ground Motion Prediction Method (“Recipe”) for Earthquakes with Specified Source Faults,” 2009 (in Japanese),
http://www.jishin.go.jp/main/chousa/09_yosokuchizu/g_furoku3.pdf [accessed September 23, 2013]
-  Earthquake Research Committee, “On the long-term evaluation of earthquakes in the Nankai Trough,” 2001 (in Japanese),
http://www .jishin.go.jp/main/chousa/01sep_nankai/index.htm [accessed September 23, 2013]
-  T. Furumura, K. Imai, and T. Maeda, “A revised source model for the 1707 Hoei earthquake and simulation of tsunami inundation of Ryujin Lake, Kyushu, Japan,” Journal of Geophysical Research, Vol.116, B02308, doi:10.1029/2010JB007918, 2011.
-  J. D. Eshelby, “The determination of the elastic field of an ellipsoidal inclusion, and related problems,” Proceedings of the Royal Society, Vol.A241, pp. 376-396, 1957.
-  H. Kanamori and D. Anderson, “Theoretical basis of some empirical relations in seismology,” Bulletin of the Seismological Society of America, Vol.65, pp. 1073-1095, 1975.
-  B. P. Allmann and P. M. Shearer, “Global variations of stress drop for moderate to large earthquakes,” Journal of Geophysical Research, Vol.114, B01310, doi: 10.1029/2008JB005821, 2009.
-  S. Murotani, H. Miyake, and K. Koketsu, “Scaling of characterized slip models for plate-boundary earthquakes,” Earth, Planets and Space, Vol.60, pp. 987-991, 2008.
-  A. Herrero and P. Bernard, “A kinematic self-similar rupture process for earthquakes,” Bulletin of the Seismological Society of America, Vol.84, pp. 1216-1228, 1994.
-  H. Nakamura and T. Miyatake, “An approximate expression of slip velocity time functions for simulation of near-field strong ground motion,” Zisin, Vol.53, pp. 1-9, 2000 (in Japanese with English abstract).
-  T. Lay, H. Kanamori, C. J. Ammon, K. D. Koper, A. R. Hutko, L. Ye, H. Yue, and T. M. Rushing, “Depth-varying rupture properties of subduction zone megathrust faults,” Journal of Geophysical Research, Vol.117, B04311, doi:10.1029/2011JB009133, 2012.
-  R. J. Geller, “Scaling relations for earthquake source parameters and magnitudes,” Bulletin of the Seismological Society of America, Vol.66, pp. 1501-1523, 1976.
-  S. Aoi and H. Fujiwara, “3-D finite difference method using discontinuous grids,” Bulletin of the Seismological Society of America, Vol.89, pp. 918-930, 1999.
-  S. Aoi, T. Hayakawa, and H. Fujiwara, “Ground motion simulator: GMS,” Butsuri Tansa. Vol.57, pp. 651-666, 2004 (in Japanese with English abstract).
-  K. Koketsu, H. Miyake, H. Fujiwara, and T. Hashimoto, “Progress towards a Japan integrated velocity structure model and long-period ground motion hazard map,” Proceedings of the 14th World Conference on Earthquake Engineering, S10-038, 2008.
-  R. W. Graves, “Simulating seismic wave propagation in 3D elastic media using staggered grid finite differences,” Bulletin of the Seismological Society of America, Vol.86, pp. 1091-1106, 1996.
-  P.Wessel andW. H. F. Smith, “New version of the Generic Mapping Tools released,” Eos Transactions, American Geophysical Union, Vol.76, p. 329, 1995.