Mapping of seismic parameters of the Iberian Peninsula by means of a geographic information system

Abstract

In this paper, the following seismic parameters, the maximum recorded magnitude ($M_{max})$, the Gutenberg–Ritcher b-value and the (normalized) mean seismic activity rate, AR, have been calculated for the Iberian Peninsula and surroundings. A geographic information system has been employed to compile all data, to work with different geographic systems and to generate the maps. An improved version of the National Geographic Institute of Spain earthquake catalog has been considered as input. Due to the detection network evolution and the extent of the territory, completeness values must be sectored to obtain reliable b-values and AR values. So, a previous work on regionalization has been considered. First, a working catalog has been elaborated. To do so, the size of some shocks through specific studies have been reviewed, magnitudes have been converted to moment magnitude ($M_{w})$ and dependent events have been removed. Second, for the b-value and the AR calculation a method that considers inhomogeneous catalogs, different magnitudes and various years of completeness has been employed. Also, different decluster parameters and various minimum number of events have been considered. Finally, to represent the values, a multi-resolution grid $(0.5^{{{\circ }}}\times 0.5^{{{\circ }}}$, $1^{{{\circ }}}\times 1^{{{\circ }}}$ and $2^{{{\circ }}}\times 2^{{{\circ }}})$ has been deployed. The pictures obtained show the seismicity in the terms of size, stress-meter and frequency. The highest $M_{max}$ has been obtained in the SW of the Iberian Peninsula with a marine epicenter. Regarding the b-value, in the contact boundary between the Africa and Eurasian plates this value is around 1.0 or minor. Contrariwise, in the mainland, values higher than 1.2 are predominant. Finally, the highest AR values are found in the SE of the Iberian Peninsula and remarkable values are also present in the NE.