Characterization of source properties of local earthquakes in Andaman Nicobar Islands with particular emphasis on their scaling relationships: Characterization of source properties of local earthquakes

The source features and their scaling relationships in the Andaman Nicobar Islands (ANI) have been estimated using the local earthquakes with local magnitude ( M L ) varying from 2 to 4.5. Brune’s spectral model has been applied to a number of 66 local earthquakes to compute source properties from both primary ( P -) and secondary ( S -) waves. Brune’s stress drop of earthquakes is obtained from both P- and S -waves by assuming a circular fault at the hypocentral depth of earthquakes and a uniform velocity of P - and S -waves. The estimate of stress drop varies between 0.02 and 23.4 bar obtained from P -waves and between 0.02 and 18.4 bar from S- waves. The seismic moment, determined by analyzing P -waves, lies between 2.0 × 10 11 and 3.6 × 10 24 N-m, whereas S -wave analysis gives an estimated range of 5.0 × 10 10 –4.9 × 10 13 N-m. Seismic moment computed from P - to S -waves show a strong correlation (96%) with each other. As per the analysis, stress drop varies with the seismic moment, and a breakdown in the law of self-similarity for the range of earthquakes analyzed in the present study is reported. The source properties and their scaling relationships that have been computed here correlate with the research conducted in other seismically active regions worldwide. The determined source properties and their scaling relationships can be applied to assess seismic hazards and explain mechanisms involved in the occurrence of earthquakes in ANI.