EVALUATION OF EARTHQUAKE HAZARD POTENTIAL OF ANDAMAN REGION, INDIA

Abstract

In the present study, a deterministic seismic hazard assessment of Andaman and Nicobar region is carried out, which is one of the most seismically active regions of India. Which usually need estimate of return period, probabilities of exceedance of specific levels of design load criteria or extreme safety conditions. Region 10°N – 15°N latitude and 91°E – 95°E longitude which exclusively include Andaman Islands have been considered for potential earthquake hazard analysis. Earthquake data from the 1973 – 2018 with magnitude Mw ≥ 4.5 have been used from the catalogue of USGS. Hazard in the region have been quantified in terms of return periods and probabilities of occurrence of earthquake of any given magnitude. The line of expected extremes (LEE) based on 46 years (1973-2018) of seismicity for the region has been plotted. The medium to large size earthquakes have been predicted. Study indicates that the most probable largest annual earthquakes are close to 5.5 and the most probable earthquake that may occur in an interval of 50 years is estimated to be 7.2. Seismic hazard analysis involves the quantitative estimation of ground shaking hazard at a particular site or for a particular region. In the present study Deterministic Seismic Hazard Analysis (DSHA) has been carried out for the Andaman region. The study area is one of the most seismically active regions. Fourteen seismotectonic sources are identified in this region. Using appropriate attenuation model the peak horizontal and peak vertical accelerations were find out. The value of peak vertical acceleration vary from 0.01g to 0.25g and peak horizontal accelerations vary from 0.03 to 0.44. The contour map for these PGA value is prepared which shows the larger PGA value present near the area where there is higher density of larger faults and vice versa