HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Electronic Supplement Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Batlló, J. Articles by Morales, J. Search for Related Content GeoRef GeoRef Citation

The 1951 M_w 5.2 and M_w 5.3 Jaén, Southern Spain, Earthquake Doublet Revisited

Institut Geològic de Catalunya, c. Balmes 209-211, E-08006 Barcelona, Spain jbatllo{at}igc.cat

D. Stich^*

Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via Donato Creti 12, I-40128 Bologna, Italy daniel{at}bo.ingv.it

B. Palombo

Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Roma, Via di Vigna Murata 605, I-00143, Roma, Italy palombo{at}ingv.it

R. Macia

Departament de Matemàtica Aplicada II, Universitat Politècnica de Catalunya, Pla de Palau 18, E-08003 Barcelona, Spain ramon.macia{at}upc.edu

J. Morales

Instituto Andaluz de Geofísica, Campus Universitario de Cartuja s/n, E-18071 Granada, Spain morales{at}iag.ugr.es

^* Present address: Instituto Andaluz de Geofísica, Campus Universitario de Cartuja s/n, E-18071 Granada, Spain.

Also at: Laboratori d’Estudis Geofisics Eduard Fontsere, Institut d’Estudis Catalans, Barcelona, Spain.

Online Material: Phase arrival times, seismograph constants for deconvolution, and color plots of probability density functions.

We collected analog seismogram recordings and seismic bulletins for two moderate magnitude earthquakes in the province of Jaén, southern Spain, on 10 March and 19 May 1951, and the series of aftershocks. Seismograms from the two main events reveal striking similarity, pointing to nearby locations and similar source mechanisms. This casts a shadow on the quality of preserved phase readings and macroseismic data, which suggests a distance of several tens of kilometers between both mainshocks and aftershocks. A critical review of available phase readings permitted us to detect several misinterpretations in the original bulletins and to obtain better constrained hypocenter relocations—about 10 km apart—for the two mainshocks, as well as location estimates for 20 aftershocks. The recording of the 1951 Jaén earthquake doublet at a network of common stations allows a straightforward quality control of our digitized seismograms by waveform comparison. We estimate faulting parameters of the two mainshocks from regional moment tensor inversion, obtaining moment magnitude M_w 5.2 and M_w 5.3, respectively, depth of 20 km, and strike-slip faulting mechanisms with minor normal slip component and northeast–southwest oriented T axes. Deconvolution of body waveforms from an M_w 4.4 aftershock yields simple triangular source time functions for both main events, with durations close to 1 sec. While several previous studies had difficulties in characterizing these earthquakes, partially describing them as unusual intermediate deep focus events, we propose simple shear faulting sources in the middle crust and faulting geometries consistent with the regional seismotectonic framework.