Scenario-based seismic hazard analysis using spectral element method in northeastern Pakistan
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Scenario‑based seismic hazard analysis using spectral element method in northeastern Pakistan Saad Khan1,2 · Mark van der Meijde2 · Harald van der Werff2 · Muhammad Shafique3 Received: 1 September 2018 / Accepted: 15 May 2020 © The Author(s) 2020
Abstract Seismic hazard analysis is carried out in this study by estimating ground motion for hypothetical earthquakes in the area of Muzaffarabad, Pakistan, with the MT solution of the 2005 Kashmir earthquake. The earth’s topography influences seismic waves by scattering and reflecting it, thereby causing spatial variation in seismic response. Using the moment tensor solution of the 2005 Kashmir earthquake, we perform 25 spectral element method (SEM)-based 3D simulations along major faults in the study area. The SEM model incorporates the topography and homogeneous half-space characteristics. Our results show that, beside topography, the relative location of the source with respect to slopes also has an influence on the observed variation in ground shaking amplitudes. By integrating the mean and standard deviation of estimated ground shaking from 25 simulations, we present a seismic hazard map for the study area. The map summarizes the topographic and potential source location effect on seismic-induced ground shaking in the study area. It provides a classification from hazardous to safe in relative terms and can be used as a guide in earthquake preparedness. Keywords Topographic amplification · Scenario earthquake · Muzaffarabad · Seismic hazard map · Spectral element method
1 Introduction Seismic hazard studies on a regional scale are carried out using either a deterministic seismic hazard analysis (DSHA) or probabilistic seismic hazard analysis (PSHA) approach. DSHA considers a worst-case scenario for a particular seismic source, referred as the * Saad Khan [email protected]; [email protected] 1
Department of Geology, Bacha Khan University Charsadda, P.O. Box 20, Charsadda, Khyber Pakhtunkhwa, Pakistan
2
Faculty of Geo‑Information Science and Earth Observation (ITC), University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
3
National Centre of Excellence in Geology (NCEG), University of Peshawar, Peshawar, Khyber Pakhtunkhwa 25120, Pakistan
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Natural Hazards
Maximum Credible Earthquake (MCE), to estimate the level of ground shaking (Reiter 1990; Kramer 1996; Bommer 2002). On the other hand, PSHA considers the likelihood of various earthquakes from multiple potential seismic sources, each having a range of uncertainty in source characteristics (e.g., rupture length, distance, fault dip, maximum magnitude, slip rate) (Abrahamson 2000; Bommer 2002). Uncertainty is treated explicitly, and the annual probability of exceeding a specified ground motion is computed. Deterministic earthquake ground motion simulation is a common technique for estimating seismic-induced ground shaking (Wang 2015). The technique uses numerical methods and models that incorporate the physics of an earthquake source and the propagation
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