Earthquake Site Response Analysis of the Layered Soil Deposits at Shakardarra and Muzaffarabad

Abstract

The mall1 objective of the present work was to test the adequacy of site response analysis to predict the effects of soil deposits on site responses during earthquakes for site conditions of Kohat Plateau and Hazara KaslU11ir Syntaxis. In the study areas, the site responses at the vertical seismograph arrays at the Shakardarra and Muzaffarabad are analyzed before any eat1hquakes, using nonlinear site response analysis program. The site response models are constructed using shear and compression wave velocity profiles from upholes, and geotechnical data avai lablc at the sites. The analysis neglected other nonlinear and geometrical efJeets such as stiffness reduction, liquefaction, two-dimensional and three-dimensional effects due to wave propagation and non-uniform soil layering. In the study of the site-response analysis an input ground acceleration oC 0.07 g is carried out for Muzaffarabad and Shalcardarra sites. Based on the results obtained, the Shakardarra and Muzaffarabad sites are fOlmd to have comparable respon ses over a wide range of earthquake motions, which is justified in view of the similarities of soil profiles at both sites. Seismological data between1964-2008 for the study area is used for analyzing seismicity pattern and structures (faults). From the analysis of Fault Plane Solutions, the Shakardarra site is undergone by active strike slip and thrust fau lts and the area is considered as structma lly deformed zone. The Shakardarra site has low to moderate Seismicity on the basis of seismicity pattern. The Peak GrOLU1d Acceleration values are compared with Fau lt Plane Solutions (FPS) of main events in the vicinity of Shakardarra for analyzing active faults and their peak values of acceleration for the site response analysis.