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Multichannel analysis of surface waves (MASW) is a non-destructive seismic prospecting method utilizing Rayleigh waves for imaging and characterizing shallow sub-surface structure. Multichannel analysis of surface waves (MASW) studies were conducted in drift areas of two bridge sites in the hilly terrain of J&K for imaging and characterizing shallow sub-surface structure. The purpose of the present study is to estimate the shear wave velocity (VS) and sub-surface structure in four drifts made in a hilly terrain for construction of two bridges. Rayleigh waves are having dispersive properties, travelling along or near the ground surface and are usually characterized by relatively low velocity, low frequency, and high amplitude. The study area comprises of Tertiary group of rocks which are underlain by Siwalik group. The main rock type in the study area is dolomite which has undergone various geological processes like weathering, jointing, fracturing and shearing. MASW data was collected inside four drifts in the mountainous terrain of J&K state which are located on either sides of Chenab river. The data was analyzed by relevant processing software using dispersion and inversion technique. Shear wave velocities were estimated up to 30 m depth. Average shear wave velocity (VS30) up to top 30m was also computed. It is observed that, VS in the range 400-800 m/s upto 10-15 m corresponding to weathered rock, followed by compact dolomite rock up to the depth of about 30 m with VS in the range 1200-1600 m/s. Some low velocity zones are also identified from these sections which represent shear zones.

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-During mining activity, the natural equilibrium of the rock mass gets altered resulting in increase in stress causing sudden, violent failure of rock mass. The stress increases with increase in the depth of mining. The dynamic stress changes caused due to release of strain energy from within the rock mass in the form of seismic signals are termed as seismic events. The occurrence of seismic events has been a regular phenomenon in and around the abandoned mines of Kolar Gold Fields causing damage to the surface structures and inducing apprehension about the safety and stability of mining areas. Among the abandoned mines, one of them had reached mining depth as deep as 3200m. In this sensitive mining area, there has been occurrence of many seismic events that were monitored by a dedicated seismic monitoring system from time to time. The monitoring system was used to determine the location of seismic events and used as an indicator of precaution from future events. In the background of this monitoring history, an attempt has been made here to assess the overall scenario of seismic hazard due to the seismic events observed over one decade. This study focuses on assessing the current probable seismic hazard for the abandoned mining region by using the estimated source parameters such as source radius, seismic magnitude obtained from the data of strong motion accelerometer supported by data from existing broad band seismometer.