Predicting topographic aggravation of seismic ground shaking by applying geospatial tools
Abstract
The undisputable impact of topographic features on the uneven distribution of seismic ground shaking and associated devastation is well-observed and documented, but not applied at a regional scale. Seismic events located in rugged terrain, such as the Kashmir earthquake (2005) in the western Himalaya, exhibit amplified response on the inclined slopes and ridge crests, while de-amplified response at the hill toe. These observations are supplemented by numerical, analytical and experimental investigations. Current efforts on predicting topographic impact on seismic response are confined to synthetic terrain or isolated hills. The available regional models, like USGS ShakeMap, ignore the topographic effects on seismic response, limiting model applicability at local scale. Parametric studies analyzing impact of specific terrain feature and seismic characteristics on seismic ground shaking resulted in numerical models, predicting topographic aggravation of seismic response. This study aims to apply DEM derived topographic attributes and seismic parameters in numerical models to predict topographic aggravation of seismic response at a regional scale.
SRTM and ASTER DEMs are utilized to derive the required topographic attributes to investigate the impact of DEM resolution and data source on computed attributes. The uncertainty in the computed topographic attributes, due to DEM inherent random error, is quantified through Monte Carlo Simulations. The impact of slope angle, aspect, height, wavelength and damping on amplification and deamplification of seismic response is analyzed in homogenous lithological and geotechnical scenario. The spatial variation of seismic wavelength is estimated empirically from instrumental ground shaking records. The remote sensing DEMs are found to be sensitive to steep slopes in terrain representation. The amplified seismic response is observed to be sensitive to the slope gradient among the analyzed parameters. The direction of incident seismic waves has significant impact on the occurrence and spatial distribution of seismic induced landslides.
References
Ashford, S.A., Sitar. N., 1997. Analysis of topographic amplification of inclined shear waves in a steep coastal bluff. Bulletin of the Seismological Society of America, 87, 692-700.
Ashford, S.A., Sitar. N., Lysmer. J., Deng.N., 1997. Topographic effects on the seismic response of steep slopes. Bulletin of the Seismological Society of America, 87, 701709.
Athanasopoulos, G.A., Pelekis. P.C., Leonidou, E.A., 1999. Effects of surface topography on seismic ground response in the Egion (Greece) 15 June 1995 earthquake. Soil Dynamics and Earthquake Engineering, 18, 135-149.
Bard, P.Y., 1982. Diffracted waves and displacement field over two-dimensional elevated topographies. Geophysical Journal International, 71, 731-760.
Bouckovalas, G.D., Papadimitriou. A.G., 2005. Numerical evaluation of slope topography effects on seismic ground motion. Soil Dynamics and Earthquake Engineering, 25, 547-558.
Carter, J. R., 1992. The effect of data precision on the calculation of slope and aspect using gridded DEMs. Cartographica, 29, 22-34.
Çelebi, M., 1987. Topographical and geological amplifications determined from strong-motion and aftershock records of the 3 March 1985 Chile earthquake. Bulletin of the
Seismological Society of America, 77, 11471167.
Chávez-García, F.J., Raptakis, D., Makra, K., Pitilakis, K., 2000. Site effects at Euroseistest—II. Results from 2D numerical modeling and comparison with observations. Soil Dynamics and Earthquake Engineering, 19, 23-39.
Florinsky, I. V., 1998. Accuracy of local topographic variables derived from digital elevation models. International Journal of Geographical Information Science, 12, 47-61.
Heuvelink, G.B.M., Burrough, P.A., Leenaers. H., 1990. Error propagation in spatial modeling with GIS. Proceedings of the First European Conference on Geographical Information Systems EGIS' 90, Amsterdam, The Netherlands, 453-462.
Kawase, H., Aki, K., 1990. Topography effect at the critical SV-wave incidence: Possible explanation of damage pattern by the Whittier Narrows, California, earthquake of 1 October 1987. Bulletin of the Seismological Society of America, 80, 1-22.
Kramer, S.L., 1996. Geotechnical earthquake engineering. Prentice Hall International Series, New Jersey, 653.
Lanter, D., Veregin, H., 1992. A research based paradigm for propagating error in layer-based GIS. Photogrammetric Engineering & Remote Sensing, 58, 825-833.
Mandal, P., Chadha, R.K., Kumar, N., Raju, P., Satyamurty, C., 2007. Source parameters of the 8 October, 2005 Mw7.6 Kashmir Earthquake. Pure and Applied Geophysics, 10.1007/s00024-007-0268-6.
Nave, R., 2000. Doing It by the Numbers: Javascript Calculations in Web-Based Instructional Material. Website: http://hyperphysics.phyastr.gsu.edu/hbase/wavrel.html, Accessed 23 December 2007.
Oksanen, J., Sarjakoski, T., 2005. Error propagation of DEM-based surface derivatives. Computers & Geosciences, 31, 1015–1027.
Pedersen, H.A., Sanchez-Sesma, F.J., CampiIlo, M., 1994. Three-dimensional scattering by two-dimensional topographies. Bulletin of the Seismological Society of America, 84, 1169-1183.
Sanchez-sesma, F.J., Herrera, I., Aviles, J., 1982. A boundary method for elastic wave diffraction: Application to scattering of SH waves by surface irregularities. Bulletin of the Seismological Society of America, 72, 473490.
Siro, L., 1982. Emergency microzonation by Italian Geodynamics Project after November 23, 1980 earthquake: a short technical report, Third International Earthquake Microzonation Conference, University of Washington, Seattle, 1417-1427.
Stamatopoulos, C.A., Bassanou, M., Brennan, A.J., Madabhushi, G., 2007. Mitigation of the seismic motion near the edge of cliff-type topographies. Soil Dynamics and Earthquake Engineering, 12, 1082-1100.
Wechsler, S.P., Kroll, C.N., 2006. Quantifying DEM uncertainty and its effect on topographic parameters. Photogrammetric Engineering & Remote Sensing, 72, 1081–1090.
