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The large or small scale of a landslide is a natural, widespread process, resulting from the downward and outward movement of slope-forming materials, such as sculpting the landscape. Characterized landslide material and properties’ inhomogeneities conditions become a challenge as the process required the availability of a wide range of data, observations, and measurements with an evaluation of geological and hydrological conditions. Detailed investigations represent an essential component of the landslide risk mitigation process, relying on subsurface investigations, discrete subsurface sampling, and laboratory tests. To extend this approach, seismic refraction and two-dimensional (2-D) resistivity were utilized to study the landslides activities in Ulu Yam. The cross-plot analysis was introduced to integrate the geophysical results based on the criteria of the model. Velocity distributions from seismic refraction revealed the stiffness of the soil, where weak zones identified with values of Vp ≤ 1200 m/s, defined as threshold frequency for failure to occur. The 2-D resistivity shows that the weak zones were identified with resistivity values of <1200 Ωm. The 2-D cross-plot model gives a comprehensive interpretation where a low velocity and resistivity value represents the failure plane of materials to failure. The volume of mass sliding was calculated based on retrieved information from the model.

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Geophysical approaches are used for site characterization to determine the dynamic behaviour of soil. Structures built on a site without sufficient assessment are prone to collapse or failure. Thus, before beginning any building activity, it is critical to assess the soil dynamic qualities. This is significant because buildings are constructed on top of the ground surface, supported by the underlying soil and rock. This work aimed to determine a competent layer for building foundations. This study was conducted to evaluate the dynamic soil behaviour of Paya Terubong on Penang Island. Resistivity, Young's modulus, shear modulus, Poisson's ratio, bulk modulus, bulk density, rippability, and material bearing capacity are among the parameters utilised for the characterization. This will be obtained from the electrical resistivity, seismic refraction, and MASW methods. Three layers were detected by these methods. Results from the study indicate that the area is mostly composed of highly dense silty sand and granitic bedrock, which makes it competent for foundation construction since higher compaction raises the ultimate and allowable bearing capacities of the third layer to very high levels. In addition, soil and rock layers identified using geophysical methods match well with the borehole data showing that material stiffness increases with depth. Rippable layers extend from the ground surface to a depth of 3 meters. The calculated values gotten from the soil dynamic properties and material bearing capacity show that the second and third layers have good geotechnical qualities. The ultimate bearing capacities calculated for the first layer range from 453 to 731 kPa, while the second layer capacities range from 1041 to 1691 kPa, and capacities for the third layer range from 2013 to 3650 kPa. For setting up structures, the second layer can support building foundations at a depth of 4 meters from the existing ground level. This approach is cost-effective, saves time, and is non-destructive for site characterization.

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