A new seismic hazard assessment in the region of Andalusia (Southern Spain)

Abstract

A probabilistic seismic hazard assessment of Andalusia (Southern Spain) in terms of peak ground acceleration, PGA, and spectral accelerations, SA(T), is presented in this paper. In contrast to most of the previous studies in the region, which were performed for PGA, making use of Intensity-to-PGA relationships, hazard was here calculated in terms of magnitude, using published spectral ground-motion models. Moreover, we considered different ground-motion models for the Atlantic sources, since the attenuation of those motions seems to be slower, as evidenced in the case of the extensive macroseismic areas of earthquakes like those occurred in the years 1755, 1969 and 2007. A comprehensive review of the seismic catalogue and of the seismogenic models proposed for the region was carried out, including those for Northern Africa, which is part of the influence area. Hazard calculations were performed following the Probabilistic Seismic Hazard Assessment (PSHA) methodology using a logic tree, which accounts for six different seismic source zonings and five different ground-motion attenuation relationships. Hazard maps in terms of PGA and SA (0.2 s) and SA (1 s) and coefficient of variation (COV) maps, for the 475-year return period were first obtained in rock sites. A geotechnical classification and amplification factors were proposed and new hazard maps including local effects were represented, showing PGA values ranging from 24 to 370 cm/s 2 for the whole Andalusian territory, with the highest expected values (PGA > 300 cm/s 2 ) in some parts of the Granada Province and in the town of Vélez Málaga. Lowest values (PGA < 50 cm/s 2 ) correspond to some towns of the Huelva 123 740 Bull Earthquake Eng (2010) 8: and Córdoba provinces. The inclusion of soil effects provides a more detailed picture of the actual hazard the region is subjected to.

Seismic hazard of the Iberian Peninsula: evaluation with kernel functions

“…Benito et al (2010) presented a study for Andalusia. The geometry of their con- tour lines is consistent with that shown in Fig.…”

“…At about the same time, Peláez-Montilla and López-Casado (2002) presented a seismic hazard analysis (SHA) for the entire Iberian Peninsula based on the methodology by Frankel (1995). Since then, several regional studies within the Iberian Peninsula have been carried out: for the south-east of Spain (García-Mayordomo et al, 2007, andGaspar-Escribano et al, 2008), for Andalusia (Benito et al, 2010), for the north of the Iberian Peninsula (Secanell et al, 2008, andGaspar-Escribano et al, 2011), for Portugal (Vilanova andFonseca, 2007, andCampos, 2009), and finally Mezcua et al (2011) have presented PGA (peak ground acceleration) results for the Spanish territory within the Iberian Peninsula.…”

Unconventional pseudostatic stability analysis of the Diezma landslide (Granada, Spain) based on a high-resolution engineering-geological model

“…1) Due to the state of activity of the Diezma landslide, earthquakes may further destabilize the slide and must be taken into account. The landslide is located in a region of moderate seismicity with a maximum peak ground acceleration (PGA) of about 0.10 g for an expected return period of 475 years (Benito et al, 2010). However, no strong earthquakes (i.e., with a moment magnitude (M w ) greater than 5.0) have occurred within 50 km of the site since the slope failure in 2001.…”

Earthquake-Induced Reactivation of Landslides: Recent Advances and Future Perspectives

“…Sine waves with maximum accelerations of 0.14 g were considered according to the available hazard maps and to the expected PGA for a return time of 475 years (Benito et al 2010); moreover, the sine waves are characterized by values of T m between 2 and 0.33 s (i.e., corresponding to seismic wavelengths within the Diezma landslide mass from 100 to 600 m).…”