Abstract
The location of Pakistan is in a collision zone among the Eurasian and Indian plate boundaries. The geological framework of
the Northwest Himalaya makes Northern Pakistan susceptible to frequent moderate to major earthquakes. The devastating earthquake
of October 8, 2005 caused 87,000 deaths, 2.8 million displacements and financial loss of 200 Billion USD equivalent to 6% GDP of
Pakistan. Islamabad is in seismically active region, the studies conducted for this region addresses the poor soil conditions, nonengineering construction practices and high level of seismic shaking. However, none of these studies provided readily available ground
maps (top 30m time average shear wave velocity Vs30, average soil shear wave velocity Vsz & depth to bed rock Dbed rock) based on site
specific geotechnical database. Vs30, Vsz & Dbed rock are important parameters for the evaluation of dynamic site characteristics of shallow
bed rock sites. In Pakistan, Uniform Building Code (UBC-1997) is currently practiced, and the site classification are defined using site
specific Vs30. In this study, geotechnical borehole database of 57 sites of Islamabad was collected to develop GIS based Vs30, Vsz & Dbed
rock maps using Standard Penetration Test value (SPT-N). The borehole database includes, SPT-N, soil description and unit weight of
soil for the Islamabad sites. In order to develop shear wave velocity (Vs) profiles, the available Vs-SPT empirical correlations were
evaluated where both SPT-N & Vs measured data is available. The average of selected bounding correlations was applied to SPT-N
database to develop representative Vs profiles. Using these Vs profiles, Vs30, Vsz & Dbed rock GIS based maps were developed by applying
Kriging interpolation in open source QGIS software. The proposed GIS maps can be used in preliminary earthquake design for seismic
resilient earthquake design in Islamabad, Pakistan.
Muhammad Shahkar, Muhammad Usman Arshad , Shamsher Sadiq, Abdul Waheed. (2021) GIS based Vs30, Vsz & Dbed rock Mapping for the Shallow Sites of Islamabad, Pakistan, Journal of Applied and Emerging Sciences, Volume-11, Issue-1.
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