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

  • Author(s): Santi Pailoplee and Punya Charusiri
  • DOI: 10.3319/TAO.2017.03.23.01
  • Keywords: Seismicity, Frequency-magnitude distribution model, Seismic hazard analysis, Laos
  • 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 0.4g in Northern Laos, whereas the ground shaking calculated from the probabilistic approach was < 0.32g for 2% probability of exceedance in the next 50 y. 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 y 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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