Deaggregation in Magnitude, Distance, and Azimuth in the South and West of the Iberian Peninsula

Abstract

We present the results of the seismic deaggregation in 15 of the most important cities with the greatest seismic hazard in the south and west of the Iberian Peninsula (Spain and Portugal). The deaggregation was carried out based on the calculation of the seismic hazard in the zone, taking into account the peak horizontal acceleration with 10% probability of exceedance in 50 years (return period of 475 years). We first performed a deaggregation study in terms of magnitude and distance in order to subsequently carry it out in azimuth. The aim of both studies is to determine the relative contribution of the different seismic foci and sources to the seismic hazard in a given location. Due to the lack of enough seismotectonic data in the study region, we could not obtain information about the contribution of specific active faults and we have not been able to include a characteristic earthquake model. However, by starting from a calculated hazard using smoothed background seismicity, it is possible to determine the contribution of the different seismic foci of the region to the seismic hazard at each location. The results reveal that there are cities where the hazard is entirely, or almost entirely, due to the local seismicity (e.g., in Portugal: Lisbon, 87%; Coimbra, 82%; in Spain: Almería, 99%; Córdoba, 99%; Granada, 99%). We have also determined that there are cities where seismic foci at 200 km away or more can be the most important or at least contribute significantly to the hazard (e.g., Beja and Faro in Portugal and Cádiz and Huelva in Spain).

Probabilistic Seismic Hazard Deaggregation for Karaj City (Iran)

“…An analogous behavior can be observed analyzing variation of mean magnitude and distance values for an MRP of 50 yr. For an MRP of 475 yr, variation of R is slightly with period and diagrams of mean distances seem close together. On the contrary, the existence of large difference between mean values of R for an MRP of 50 yr, especially for periods of greater than 0.5 s reveals that more than one seismic source contribute significantly to the site hazard for those spectral periods (Montilla et al, 2002).…”

“…The seismic hazard deaggregation process has been performed by Bernreuter (1992) for the first time and following this study, deaggregation methods and applications were extensively discussed and improved by Chapman (1995;McGuire, 1995;Cramer and Petersen, 1996;Bazzurro and Cornell, 1999;Harmsen et al, 1999;Sokolov, 2000;Harmsen, 2001;Harmsen and Frankel, 2001;Montilla et al, 2002;Halchuk and Adams, 2004), etc. In order to perform deaggregation of seismic hazard for Karaj city, probabilistic seismic hazard assessment is evaluated for the study area (yellow area in Fig.…”

Seismic Response of a Cantilevered Highway Sign Support Without and With a TMD Damper

“…Hazard disaggregation in Portugal (and Iberian Peninsula) was conducted in the works of [7]- [8], for example. Taking into account specific appreciations made in reference [9], the results of [8] were followed.…”

“…Taking into account specific appreciations made in reference [9], the results of [8] were followed. In addition to that there is some information in the Portuguese National Annex EC8-1-5 [10], which provides representative magnitudes for a return period of 475 years.…”

“…In addition to that there is some information in the Portuguese National Annex EC8-1-5 [10], which provides representative magnitudes for a return period of 475 years. For Faro municipality the magnitude adopted according with EC8-1-5 was 7.5, and a distance (mean value) of 123 km, this consists in a distant-earthquake scenario with scattered seismicity around the Gulf of Cadiz and West Cape San Vicente as mentioned by Montilla et al [8].…”