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Microtremor measurements become one of the widely accepted tools to evaluate the site response characteristics since the last two decades. These measurements have been conducted at four sites inside King Abdulaziz City for Science and Technology (KACST), Riyadh city, Saudi Arabia to estimate the resonance frequency and the associated amplitude of sediments. Microtremor measurements have been recorded for 24 h with a sampling frequency of 100 Hz in the range from 0.2 to 25 Hz band-pass filter. Origin of the identified peaks has been tested. The estimated peaks are correlated with borehole geotechnical data: (1) the first peak with an average frequency of 8.25 Hz that reflects the impedance contrast between the uppermost surface soil and the underlying completely weathered limestone and (2) the second peak of 1.43 Hz which corresponds to the impedance contrast between the completely weathered limestone and the underlying limestone rocks. In addition, the relation between sediment thickness and resonance frequency has been assessed. Based on the results of this study, it can be stated that microtremor measurements are capable to estimate thickness of sedimentary overburden. These results will support for seismic safety in case of civil engineering constructs in KACST area.

Mineral resources exploration in the Kingdom of Saudi Arabia became an important target for the Saudi government. Nowadays, the economic vision of the country is to move away from oilbased country to multisource energy-based country. In Baljurashi area there were ancient mines for Copper, Cobalt, Magnesium, Zircon, and some other minerals. In the current study, we aim to evaluate the Baljurashi area in terms of mineral resources using the advanced technique. Consequently, we carried out ground gamma ray spectrometry survey in an area of about 50 km 2 , elevation variation ranges from 380 m to 2280 m above the sea level. We used the RS-700 system to collect the gamma ray spectrometry data. In addition, we used the existing geochemical analysis results for this area and integrated the results to map the most important minerals. The integration work indicates that the area of Baljurashi is rich in mineral resources. The mineralization zones are located in the eastern part of the area where elevation is high (e.g., east of the escarpment). We also found that these mineralization zones are structurally controlled. Important mineral maps were produced (e.g. Cu, Cr, Mn, and Zr). We highly recommend more geophysical studies to evaluate the Baljurashi area for mineral identifications and quantifications.