Natural Hazards in El Salvador
Seismic hazard assessments, seismic design codes, and earthquake engineering in El Salvador
Published:January 01, 2004
Manuel López, Julian J. Bommer, Rui Pinho, 2004. "Seismic hazard assessments, seismic design codes, and earthquake engineering in El Salvador", Natural Hazards in El Salvador, William I. Rose, Julian J. Bommer, Dina L. López, Michael J. Carr, Jon J. Major
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Seismic hazard is very high in parts of El Salvador, with destructive earthquakes occurring on average at least once per decade. Probabilistic estimates of the hazard published by various researchers differ appreciably, in large part due to the uncertainties associated with the earthquake catalog and the sparse database of strong-motion accelerograms. Proposals have been put forward to create two seismic zonation maps, one for upper crustal events and another for earthquakes in the subducted Cocos plate. Observed differences in the spatial distribution and specific characteristics of ground shaking caused by the two types of earthquakes support this proposal, but it is clear that site effects are also of great importance, hence seismic microzonation is also required for urban areas. The high level of seismic hazard in El Salvador makes an appropriate code for the earthquake-resistant design of buildings a vital tool for risk mitigation. Seismic codes have been published in 1966, 1989, and 1994, the most recent being a reasonably comprehensive and technically robust set of guidelines. The effectiveness of the current code to reduce seismic risk in El Salvador is low, but not because of technical deficiencies in the requirements for structural design. The most serious deficiency is clearly defined as the complete lack of any effective mechanism for the enforcement of the code requirements for minimum levels of seismic resistance. Another important element of the risk in El Salvador, which is due to the frequency of destructive events, is lack of adequate repair and strengthening of damaged buildings, an issue not addressed by the code.