Lee, Shiann-Jong and Chan, Yu-Chang and Komatitsch, Dimitri and Huang, Bor-Shouh and Tromp, Jeroen (2009) Effects of Realistic Surface Topography on Seismic Ground Motion in the Yangminshan Region of Taiwan Based Upon the Spectral-Element Method and LiDAR DTM. Bulletin of the Seismological Society of America, 99 (2A). pp. 681-693. ISSN 0037-1106 http://resolver.caltech.edu/CaltechAUTHORS:20090904-110333350
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We combine light detection and ranging (LiDAR) digital terrain model (DTM) data and an improved mesh implementation to investigate the effects of high-resolution surface topography on seismic ground motion based upon the spectral-element method. In general, topography increases the amplitude of shaking at mountain tops and ridges, whereas valleys usually have reduced ground motion, as has been observed in both records from past earthquakes and numerical simulations. However, the effects of realistic topography on ground motion have not often been clearly characterized in numerical simulations, especially the seismic response of the true ground surface. Here, we use LiDAR DTM data, which provide two-meter resolution at the free surface, and a spectral-element method to simulate three-dimensional (3D) seismic-wave propagation in the Yangminshan region in Taiwan, incorporating the effects of realistic topography. A smoothed topographic map is employed beneath the model surface in order to decrease mesh distortions due to steep ground surfaces. Numerical simulations show that seismic shaking in mountainous areas is strongly affected by topography and source frequency content. The amplification of ground motion mainly occurs at the tops of hills and ridges whilst the valleys and flat-topped hills experience lower levels of ground shaking. Interaction between small-scale topographic features and high-frequency surface waves can produce unusually strong shaking. We demonstrate that topographic variations can change peak ground acceleration (PGA) values by ±50% in mountainous areas, and the relative change in PGA between a valley and a ridge can be as high as a factor of 2 compared to a flat surface response. This suggests that high-resolution, realistic topographic features should be taken into account in seismic hazard analysis, especially for densely populated mountainous areas.
|Additional Information:||© 2009 Seismological Society of America. Manuscript received 4 January 2008. This research was supported by the Taiwan Earthquake Research Center (TEC) funded through the National Science Council (NSC) with Grant Number NSC95-2745-M-001-004 and the U.S. National Science Foundation under Grant Number 0711177. The simulations are carried out on Caltech’s CITerra Dell cluster. The TEC contribution number for this article is 00049. This is Contribution Number 8993 of the Division of Geological and Planetary Sciences, California Institute of Technology.|
|Subject Keywords:||Asia; digital terrain models; earthquakes; effects; Far East; geologic hazards; ground motion; laser methods; lidar methods; numerical analysis; processes; propagation; radar methods; risk assessment; seismic risk; simulation; spectral analysis; Taiwan; topography; Yangminshan Taiwan|
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|Official Citation:||Shiann-Jong Lee, Yu-Chang Chan, Dimitri Komatitsch, Bor-Shouh Huang, and Jeroen Tromp Effects of realistic surface topography on seismic ground motion in the Yangminshan region of Taiwan based upon the spectral-element method and lidar DTM Bulletin of the Seismological Society of America (April 2009), 99(2A):681-693|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||George Porter|
|Deposited On:||22 Sep 2009 17:51|
|Last Modified:||26 Dec 2012 11:19|
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