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A Study of Seismic Risk for Nicaragua. Part I.
Shah, H. C.; Mortgat, C. P.; Kiremidjian, A.; Zsutty, T. C.
National Science Foundation, Washington, DC. Engineering and Applied Science., January 1975, 351 p.
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The geological setting for the country in general and the Managua area in particular is described. The data base for past seismic events was extensively studied. Limitations of the data and approximations are discussed. Seismic recurrence for ten line sources and three area sources was developed. Based on the assumption of the Poisson occurrence of seismic events, probabilities of exceeding different magnitude levels as functions of time for different regions were derived. Using Esteva's attenuation relationship, isoacceleration maps for the country were constructed. Eleven cities in Nicaragua were considered in this mapping process. Cumulative distribution functions of peak ground accelerations for 20 and 50 years were established. This is shown to be one way of presenting seismic risk for Nicaragua. Based on isoacceleration maps, the Acceleration Zone Graphs (AZG) were developed for the eleven cities. A method for determining load levels for consistent risk for the whole country is discussed and suggested. It is proposed that charts such as AZG be used for seismic zoning of Nicaragua. Ground acceleration values from AZG were employed to set the level of the design spectra for structural damage prevention and condemnation control. A design methodology is proposed based on ultimate strength and loads resulting from the above inelastic design spectra.
Risk; Computer programs; Earthquake engineering; Risk analysis; Geological surveys; Nicaragua; Seismology; Predictions; Economic factors; Geological faults; Seismic risk