Shear wave velocity structure at King Saud University, Saudi Arabia, derived from MASW and microtremor arrays.

Abstract

Shear wave velocity (Vs) is an essential parameter for soil strength and mechanical properties of rocks. Twenty profiles of multichannel analysis of surface waves (MASW), five microtremor measurements, and two geotechnical boreholes have been conducted at the King Saud University site. According to the National Earthquake Hazards Reduction Program classification, the results indicated three distinct layers. The first layer is comprised of silty sand with gravel and thickness ranges of 4-14 m of shear wave velocity (Vs) from 400 to 760 m/s, indicating site C class; the second layer features highly weathered limestone where Vs varies between 760 and 1500 m/s refers B class, while the third layer consists of compact/massive limestone where Vs varies from 1500 to 3500 m/s representing site A class. The bedrock varies in depth from south to north, showing the shallowest depth in the central zone. Moreover, the estimated shear wave velocity and bedrock depth from microtremor measurements agree with MASW results. These results specified distinct weak zones at depths ranging from 2 to 25 m through the study area, emphasizing potential geotechnical concerns associated with these weak zones. Integrating shear wave velocity and microtremor measurements is crucial for advancing sustainable urban development by providing more informed design choices considering local soil conditions. This highlights the significance of geophysical techniques in supporting sustainable development initiatives.