Standardization of Seismic Microzonification and Probabilistic Seismic Hazard Study Considering Site Effect for Metropolitan Areas in the State of Veracruz

Preliminary results obtained from the project "Seismic Hazard in the State of Veracruz and Xalapa Conurbation" and "Microzonation of geological and hydrometeorological hazards for conurbations of Orizaba, Veracruz, and major sites located in the lower sub-basins: The Antigua and Jamapa" are presented. These projects were sponsored respectively by the PROMEP program and the Joint Funds CONACyT-Veracruz state government.

The study consists of evaluating the probabilistic seismic hazard considering the site effect (SE) in the urban zones of cities of Xalapa and Orizaba; the site effects in this preliminary stage were incorporated through a standard format proposed in studies of microzonation and application in computer systems, which allows to optimize and condense microzonation studies of a city.

This study stems from the need to know the seismic hazard (SH) in the State of Veracruz and its major cities, defining SH as the probabilistic description of exceedance of a given level of ground motion intensity (generally designated by the acceleration soil or maximum ordinate in the response spectrum of pseudo-acceleration, PGA and Sa, respectively) as a result of the action of an earthquake in the area of influence for a specified period of time.

The evaluation results are presented through maps of seismic hazard exceedance rate curves and uniform hazard spectra (UHS) for different spectral ordinates and return periods, respectively.