This paper presents the procedure proposed by the ISO code adapted to the local conditions in the Bay of Campeche, Mexico in order to obtain design spectrum for different seismic reserve capacity factors. A probabilistic seismic hazard analyses is used in order to determine the uniform hazard spectrum where the seismic environment, according to previous researches, is influenced by three primary types of earthquake sources: the subduction zone on the western pacific coast of Mexico, the lithospheric slab within the central portion of Mexico and the trans-mexican volcanic belt. This earthquake spatial distribution can be shown trough the historic catalog of earthquake occurrences during the period 1900-2001 used. On the one hand, in the evaluation of the characteristics and the uncertainties associated with the earthquake sources and their effects on the interest sites, are taken into account the characterization of the earthquake sources, the effect of the seismic wave propagation, the local conditions and the soil-structure interaction developed during earthquake ground motions. On the other hand, the uncertainties on the seismic hazard curve and those associated with the platform behavior (mass, stiffness, damping) in which their values are assigned to be consistent with the ISO 19901-2 and ISO 19902 seismic code suggestions. The final result consists in a seismic design spectrum for offshore platforms at the Bay of Campeche, which are consistent with the recommended ISO 19902 seismic reserve capacity factors, modified for local soil conditions, following a detailed seismic-action procedure.
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