Analyses of seismic activities and hazards in Laos: A seismicity approach

  • Earthquake catalogue was utilized as the main dataset
  • Earthquake activities were analysed by the frequency-magnitude distribution model
  • Seismic hazard was analysed by the earthquake activities and suitable attenuation model

The seismic activities and hazards in People’s Democratic Republic Laos were analyzed using the most up-to-date seismicity data. Both the a- and b-values of the frequency-magnitude distribution model, including the return period of earthquake magnitude in the range of 5.0 - 6.0 Mw, were evaluated spatially in a region that ex­tends 300 km from Laos. Six seismic source zones with different seismic activities were found. Based on these seismic source zones and a suitable attenuation model, seismic hazards were then analyzed in both deterministic and probabilistic scenarios. The deterministic map showed a possible maximum ground shaking up to 0.4 g in Northern Laos, whereas the ground shaking calculated from the probabilistic ap­proach was < 0.32 g for 2% probability of exceedance in the next 50 yr. The prob­ability of exceedance of an earthquake with a Modified Mercalli intensity scale of level IV - V, VI and VII in Laos in the next 50 yr was > 90, 70 - 90, and 20 - 40%, respectively, and was higher in the northern part. From these seismic activities and hazard analyses, Laos can be clearly separated into the three hazard zones of north­western, northeastern and southern Laos with a high, medium and low earthquake hazard, respectively. Therefore, effective mitigation plans to reduce the impact of seismic hazards should be formulated and in particular for a number of major prov­inces located in the northern part of Laos.


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