Reevaluation of the earthquake catalog for Spain using the EMS-98 scale for the period 1900–1962

Abstract

This study uses a systematic methodology for the re-evaluation and analysis of earthquakes in the first half of the 20th century in Spain, a period with very inhomogeneous information sources. To the best of our knowledge, these earthquakes have never been previously re-evaluated using as many information sources as the collected in this paper. The methodology used in this paper has been tested in SE Spain for further application in the rest of the Iberian Peninsula. We have collected and thoroughly revised all the seismic information and data sources available, ranging from specific reports, macroseismic questionnaires, and seismograms to newspapers and pictures. In addition, for a set of 16 earthquakes between 1900 and 1962 in the selected area, we provide EMS-98 intensities and macroseismic epicenters, except for one that is instrumental. Among the 16 earthquakes, it has only been possible to provide a depth value for eight of them. The seismic intensities have been evaluated using the intensity scale EMS-98, and the epicenters have been located with both instrumental methods (Hypocenter location) and macroseismic methods (such as Bakun, Boxer 4.0 and MEEP 2.0). Our results show that, Imax (maximum seismic intensity) values from the IGN catalogue are larger in more than the half of the revised earthquakes by between a half degree to two-and-a-half degrees, and only for Lorqu & iacute; earthquake on April 25th, 1912, the Imax was smaller by half a degree. Most of the epicenters were also updated with changes between 1 and 41 km. Focal depths are less than 10 km, but this parameter has large uncertainties. The result of this study is a homogeneous seismic catalog (re-evaluated epicenters and Imax) for the period 1900-1962 that can be compared with periods prior to the 20th century.