Topographically-Derived Near-Surface Shear Wave Velocity Map for Pakistan

Abstract

Shear wave velocity ([Formula: see text]) through the uppermost subsurface (30 m) is usually considered an important parameter as it dictates the dynamic behavior of soil and also acts as an input parameter for site response analysis, seismic hazard analysis, and site classification. In majority of seismically active areas across the globe, especially in developing countries like Pakistan, the [Formula: see text] measurements are either not available or if available, they are very limited in number to develop a seismic site-conditions map. In the absence of proper geological studies and geotechnical investigation, the slope-derived method provides a simple solution to map the site-conditions. The current study presents the development of slope-derived [Formula: see text] map on the basis of a correlation between [Formula: see text] and topographic slope for active tectonic regions and its comparison with the [Formula: see text] values at various locations in Pakistan. The topographic slope is calculated from digital elevation model (CDEM) of the Shuttle Radar Topography Mission (SRTM) 30 arc-sec global topographic data set. The [Formula: see text] values comprise of directly available, values calculated/estimated from the standard penetration tests (SPTs [Formula: see text]-value) and primary waves at various locations in Pakistan. [Formula: see text] values at various parts/locations in Pakistan and values from the slope-derived [Formula: see text] map are found to be fairly comparable and based on these results for seismically active areas like Pakistan, slope-derived method can be applied for the first-order site-condition studies.