Abstract
Two earthquakes occurred in the Ligurian Sea in December 1989 and April 1990. Both were widely felt along the French and Italian Rivieras, thus reminding us of the seismic risk in this region. The significant increase in the number of seismic stations in the area facilitated the study of these two shocks and their related aftershocks. Using different techniques (absolute and relative hypocentral locations, doublet analysis and waveform modeling), we computed accurate hypocentral locations and estimated the location-error range for earthquakes in this area. We also computed the focal mechanisms for both mainshocks, and we present here a synthesis that integrates previous data. The reactivation in compression of the Ligurian Sea sphenochasm is confirmed, which would eventually result in the closing of an aborted oceanic domain. As the seismic activity is clearly restricted to the northern margin, we suggest it locally results from the lateral expulsion of the south-western Alps along the Apulian indenter.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Angelier, J. (1979),Determination of the Mean Principal Directions of Stresses for a Given Fault Population, Tectonophys.56, T17-T26.
Armijo, R., andCisternas, A. (1978),Un problème inverse en microtectonique cassante, Comptes rendus Acad. des Sci.D 287, 595–598.
Bertil, D., Bethoux, N., Campillo, M., andMassinon, B. (1989),Modeling Crustal Phases in Southeast France for Focal Depth Determination, Earth Planet. Sci. Lett.95, 341–358.
Bethoux, N., Petit, F., Réhault, J.-P., Massinon, B., andMontagnier, J.-P. (1986),Several Location Methods for Underwater Shots in the Gulf of Genoa (Western Mediterranean): Structural Implications, Tectonophys.128, 357–379.
Bethoux, N., Cattaneo, M., Delpech, P.-Y., Eva, C., andRéhault, J.-P. (1988),Mécanismes au foyer de séismes en mer, Ligure et dans le sud des Alpes occidentales: résultats et interprétation, Compte rendus Acad. des Sci.307 sér. 2, 71–77.
Bossolasco, M., andEva, C. (1965),Il terremoto del 19 Luglio 1963 con epicentro nel mar Ligure, Geofis. e Meteor.14, 6–18.
Bossolasco, M., Cicconi, G., Eva, C., andPasquale, V. (1972),La rete sismica dell'Istituto Geofisico di Genova e primi risulti sulla sismotettonica delle Alpi maritime e occodentali e del Mar Ligure, Riv. Ita. Geofis.23, 57–63.
Bouchon, M., andAki, K. (1977),Discrete Wave-number Representation of Seismic Source Wave Fields, Bull. Seismol. Soc. Am.67, 259–277.
Campillo, M., Bouchon, M., andMassinon, B. (1984),Theoretical Study of the Excitation, Spectral Characteristics and Geometrical Attenuation of Regional Seismic Phases. Bull. Seismol. Soc. Am.74, 79–90.
Capponi, G., Eva, C., andMerlanti, F. (1980),Il terremoto del 23 Febbraio 1887 in Liguria occidentale, Atti dell'Acad. Ligure di Sci. e Lett.37, 1–33.
Cattaneo, M., Eva, C., andMerlanti, F. (1985),Crustal Inhomogeneities in Northwestern Italy as Inferred by Pn Wave Travel Time Residuals, Tectonophys.118, 143–158.
Célérier, B. (1988),How Much Does Slip on a Reactived Fault Plane Constrain the Stress Tensor? Tectonics7, 1257–1278.
Fréchet, J.,Sismicité du Sud-Est de la France, une nouvelle méthode de zonage sismique (Thèse de 3ème cycle Univ. Grenoble, Grenoble 1978).
Fréchet, J.,Sismogenèse et doublets sismiques (Thése d'Etat Univ. Grenoble, Grenoble 1985).
Guyoton, F.,Sismicité et structure lithosphérique des Alpes occidentales (Thèse de Doctorat Univ. Grenoble, Grenoble 1991).
Hoang-Trong, P., Haessler, H., Holl, J.-M., andLegros, Y. (1987),L'essaim sismique (Oct. 83–Jan. 84) de la moyenne vallée de la Roya (Alpes-Maritimes): activité récente d'un ancien système de failles conjuguées? Comptes rendus Acad. des Sci.304 sér. 2, 419–424.
le Cann, C.,Le diapirisme dans le bassin liguro-pronvencal: relations avec la sédimentation et la tectonique, conséquences géodynamiques (Thèse de Doctorat Univ. Bret. Occ., Brest 1987).
Lemoine, M., Dardeau, G., Delpech, P.-Y., Dumont, T., de Graciansky, C., Graham, R., Jolivet, L., Roberts, D., andTricart, P. (1969),Extension synrift et failles transformantes jurassiques dens les Alpes Occidentales, Comptes rendus Acad des Sci.309 sér. 2, 1711–1716.
McKenzie, D. P. (1969),The Relation between Fault Plane Solutions for Earthquakes and the Directions of the Principal Stresses, Bull. Seismol. Soc. Am.59, 591–601.
McKenzie, D. P. (1970),Plate Tectonics of the Mediterranean Region, Nature226, 239–243.
Mantovani, M.,Alcune considerazioni sismo-tettoniche sul bacino Ligure (Thesis Univ. Genova, Genova 1983).
Massinon, B.,Vue d'ensemble de la sismicité instrumentale en France de 1962 à 1976, InLes tremblements de terre en France (ed. Vogt, J.) (mém. B.R.G.M.96, Orléans 1979) pp. 193–204.
Pautot, G., Le Cann, C., Coutelle, A., andMart, Y. (1984),Morphology and Extension of the Evaporite Structures of the Liguro-Provencal Basin: New Sea-beam Data, Marine Geol.55, 387–409.
Philip, H. (1987),Plio-Quaternary Evolution of the Stress Field in Mediterranean Zones of Subduction and Collision, Annales Geophysicae5B, 301–320.
Poupinet, G., Ellsworth, W. L., andFréchet, J. (1984),Monitoring Velocity Variations in the Crust Using Earthquake Doublets: An Application to the Calaveras Fault, California, J. Geophys. Res.89, 5719–5731.
Reasenberg, P., andOppenheimer, D. (1985),FPFIT, FPPLOT and FPPAGE: Fortran Computer Programs for Calculating and Displaying Earthquake Fault-plane Solutions, U.S. Geol. Surv. Open-File Rep., 85-739.
Recq, M., Réhault, J.-P., Bellaiche, G., Gennesseaux, M., andEsteve, J.-P. (1976),Unités structurales de la marge continentale sous-marine de Cannes à Menton d'après la sismique réfraction, Earth and Planet. Sci. Lett.28, 323–330.
Réhault, J.-P.,Evolution tectonique et sédimentaire du bassin Ligure (Méditerranée occidentale) (Thèse d'Etat Univ. Paris VI, Paris 1981).
Réhault, J.-P., andBethoux, N. (1984),Earthquake Relocation in the Ligurian Sea (Western Mediterranean): Geological Interpretation, Mar. Geol.55, 429–445.
Ritz, J.-F., Hoang-Trong, P., Rebaï, S., Philip, H., andHerquel, G. (1990),Le séisme du 26 décembre 1989 en Méditerranée, au large de la côte d'Azur: tectonique active en compression, perturbation de contraintes et inversion tectonique au niveau d'une marge continentale, Comptes rendus Acad. des Sci.310 sér. 2, 1505–1512.
Ritz, J.-F.,Champ de contrainte dans les Alpes du Sud depuis 25 millions d'années. Implications géodynamiques et sismotectoniques (Thèse de Doctorat Univ. Montpellier, Montpellier 1991).
Vialon, P., Rochette, P., andMénard, G. Indentation and rotation in the western Alpine arc. InAlpine Tectonics (eds. Coward, M. P., Dietrich, D., and Park, R. G.) (Geol. Soc. Spec. Publ.45, London 1989) pp. 326–338.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bethoux, N., Fréchet, J., Guyoton, F. et al. A closing Ligurian Sea?. PAGEOPH 139, 179–194 (1992). https://doi.org/10.1007/BF00876326
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00876326