Probabilistic assessment of earthquake hazard in Vietnam based on seismotectonic regionalization

Abstract

The theory of extreme values is applied to the earthquake source zones of Vietnam, using the first and third Gumbel's asymptotic distributions. Data are taken from the earthquake catalogues of Vietnam for the period 1903–1988. For each source zone and for the two main parts of the territory, the characteristics of earthquake activity are estimated. Also the mean return periods for earthquakes of different magnitudes and the probability of their occurrences for a set of return periods are calculated. The highest value of the maximum earthquake magnitude ( M max = 7.0) is predicted for the Ma river source zone and for the whole northern part of Vietnam, within a return period of 123 years. For North Vietnam, the occurrence of earthquakes with magnitudes not less than 6.0 within 50 years is predicted with 90% probability, while for South Vietnam the occurrence of earthquakes with magnitudes exceeding 5.0 is predicted for the same time interval with about 80% probability. From the results it follows that the third distribution fits the observation much better than the first one.