Soil liquefaction susceptibility of Jizan coastal area, southwest Saudi Arabia, based on microtremor measurements

The purpose of this study is to investigate soil liquefaction in Jizan city using the horizontal-to-vertical spectral ratio (HVSR) microtremor measurements which were taken at 140 locations across the city. In Jizan, evaluating liquefaction probability is critical for land use planning. Jizan ground surface is made up of soft sand to silty clay deposits, and the groundwater level is less than 2 m deep. Moreover, Jizan is located in an earthquake-prone area of the southern Red Sea earthquake-active zone and has been impacted by earthquakes throughout history. As a result, earthquakes with magnitudes greater than 5 on the Richter scale can cause liquefaction in these soils. The fundamental frequency ( f 0 ) and accompanying amplification factor ( A 0 ) of this data were calculated utilizing international software. The vulnerability index, Kg, and ground shear strain γ were used to assess the likelihood of soil liquefaction. The peak frequencies of HVSR range from 0.25 to 3.3 Hz, with corresponding peak amplitudes ranging from 1.0 to 17.75. While Kg and γ range from 2.46 to 655.72 and 0.75 × 10 −4 to 2.56 × 10 −4 , respectively. The findings imply that the city of Jizan’s near-surface saturated sediments (down to a depth of 10 m) are very susceptible to liquefaction, particularly in the city’s northern urban extensions along the coastal plain. These results should be considered by policymakers in Jizan Municipality to mitigate the liquefaction hazardous impacts on the important facilities and infrastructures in the Jizan city.