Seismotectonic characterization of the Becerreá area (NW Spain)
DOI:
https://doi.org/10.1344/105.000001750Keywords:
Northwest Iberia Becerreá fault, Intraplate earthquakes, Fault interaction, Temporary arrayAbstract
The NW sector of the Iberian Peninsula has been classically considered as a seismically stable area, with only dispersed and low-magnitude activity. Around the village of Becerreá (Lugo) a significant concentration of earthquakes is observed. Since the beginning of instrumental record in 1979, seven seismic crisis have been reported in that zone, including 14 events of magnitude gt>4 and a larger event of magnitude 5.1mbLg (VII EMS) in 1997. Even if this seismicity is to be related to the general compressive regime between Africa and Eurasia, the seismotectonic characterization of the area is still controversial, as the different hypotheses considered are based on insufficiently accurate data. New insights to the problem are discussed here, coming from the deployment of a seismic portable network between 1999 and 2002, which has provided new accurate seismic data. The corresponding events are distributed around a subvertical axis, reaching a depth of 12km, and epicentres tend to concentrate beneath the intersection of the main Becerreá fault and secondary, ENE/WSW oriented faults. This intersection structure is thus interpreted as being responsible for the relatively high level of seismic activity over the area.References
Alonso, J., Pulgar, J., García-Ramos, J., Barba, P., 1996. Tertiary basins and Alpine tectonics in the Cantabrian Mountain (NW Spain). In: Friend, P., Dabrio, C. (eds.). Tertiary basins of Spain. Cambridge, Cambridge University Press, 19-22.
Ayarza, P., Martínez Catalán, J.R., Gallart, J., Pulgar, J.A., 1998. Estudio Sísmico de la Corteza Ibérica Norte 3.3: A seismic image of the Variscan crust in the hinterland of the NW Iberian Massif. Tectonics, 17(2), 171-186.
Calais, E., DeMets, C., Nocquet, J.M., 2003. Evidence for a post-3.16- Ma change in Nubia–Eurasia–North America plate motions? Earth and Planetary Science Letters, 216, 8-92.
Capote, R., Martínez-Díaz, J.J., Tsige, M., Villamor, P., 1999. El marco tectónico de la sismicidad en el área de Sarria-Triacastela-Becerreá (provincia de Lugo). I Asamblea Hispano Portuguesa de Geodesia y Geofísica. Almería (Spain), Instituto Nacional de Geofísica, extended abstracts. CD-ROM ISBN: 84-95172-10-0.
Córdoba, D., Banda, E., Ansorge, J., 1987. The Hercynian crust in northwestern Spain: a seismic survey. Tectonophysics, 132, 321-333.
DeMets, C., Gordon, R.G., Argus, D.F., Stein, S., 1994. Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions. Geophysical Research Letters, 21, 2191-2194.
De Vicente, G., Cloetingh, S., Muñoz-Martín, A., Olaiz, A., Stich, D., Vegas, R., Galindo-Zaldivar, J., Fernández-Lozano, J., 2008. Inversion of moment tensor focal mechanisms for active stresses around Microcontinent Iberia: Tectonic implications. Tectonics, 27, 1-22.
De Vicente, G., Giner, J.L., Muñoz-Martín, A., González-Casado, J.M., Lindo, R., 1996. Determination of present-day stress tensor and neotectonic interval in the Spanish Central System and Madrid Basin, central Spain. Tectonophysics, 266, 405-424.
De Vicente, G., Martín-Velázquez, S., Rodríguez-Pascua, M.A., Muñoz-Martín, A., Arcilla, M., Andeweg, B., 2000. Características de los tensores de esfuerzos activos entre la Dorsal Centroatlántica y la Península Ibérica. Geotemas, 1(1), 95-98.
Díaz, J., Gallart, J., 2009. Crustal structure beneath the Iberian Peninsula and surrounding waters: a new compilation of deep seismic sounding results. Physics of the Earth and Planetary Interiors, 173, 181-190. doi: 10.1016/j.pepi.2008.11.008
Díaz, J., Gallart, J., Gaspà, O., Ruiz, M., Córdoba, D., 2008. Seismicity analysis at the ‘Prestige’ oil-tanker wreck area (Galicia Margin, NW of Iberia). Marine Geology, 249, 150-165.
Díaz, J., Gallart, J., Ruiz, M., Pulgar, J.A., López, C., González-Cortina, J.M., 2002. Anisotropic features of the alpine lithosphere in Northern Spain. Geophysical Research Letters, 29(24), 2225. doi:10.1029/2002GL015997
Díaz, J., Gallart, J., Pedreira, D., Pulgar, J.A., Ruiz, M., López, C., González-Cortina, J.M., 2003. Teleseismic imaging of alpine crustal underthrusting beneath N Iberia. Geophysical Research Letters, 30(11), 1554. doi.10.1029/2003GL017073
Díaz, J., Gallart, J., Ruiz, M., Pulgar, J.A., López-Fernández, C., González-Cortina, J.M., 2006. Probing seismic anisotropy in North Iberia from shear wave splitting. Physics of the Earth and Planetary Interiors, 158, 210-225.
Fernández-Viejo, G., Gallart, J., Pulgar, J., Córdoba, D., Dañobeitia, J., 2000. Seismic signature of Variscan and Alpine tectonics in NW Iberia: Crustal structure of the Cantabrian Mountains and Duero basin. Journal of Geophyical Research, 105, 3001-3018.
Fernández-Viejo, G., Gallart, J., Pulgar, J., Gallastegui, J., Dañobeitia, J., Córdoba, D., 1998. Crustal transition between continental and oceanic domains along the North Iberian Margin from wide-angle seismic and gravity data. Geophysical Research Letters, 25(23), 4249-4252.
Gallastegui, J., Pulgar, J., Gallart, J., 2002. Initiation of and active margin at the North Iberian continent-ocean transition. Tectonics, 21(4), 1033. doi: 10.1029/2001TC901046
Goldstein, P., Minner, L., 1996. SAC2000: seismic signal processing and analysis tools for the 21st Century. Seismological Research Letters, 67, 39.
Herraiz, M., De Vicente, G., Lindo-Ñaupari, R., Giner, J., Simón, J., González-Casado, J., 2000. The recent (upper Miocene to Quaternary) and present tectonic stress distributions in the Iberian Peninsula. Tectonics, 19(4), 762-786.
Julivert, M., Fontboté, J.M., Ribeiro, A., Conde, L., 1972. Mapa Tectónico de la Península Ibérica y Baleares. Scale 1:1.000.000. Instituto Geológico y Minero de España, 113pp.
Lee, W., Lahr, J., 1975. HYPO71 (revised): a computer program for determining hypocenter magnitude and first motion pattern of local earthquakes. Open-File Report, 75, 311.
López-Fernández, C., Pulgar, J., Gallart, J., Díaz, J., González-Cortina, J., Ruíz, M., 2004. Present seismicity and tectonics in the NW Iberian Peninsula (Spain): results from the GASPI project. Geophysical Research Abstracts, 6, EGU04-A-04142-1.
López-Fernández, C., Pulgar, J., Gallart, J., Díaz, J., González-Cortina, J., Ruíz, M., 2008. Zonación sismotectónica del NO de la Península Ibérica. VII Congreso Geológico de España. Las Palmas de Gran Canaria, Spain. Geotemas, 10, 1031-1034.
Lotze, F., 1945. Zur Gliederung der Variszden der Iberischen Meseta. Geotekt Forsch, 6, 78-92.
Marcos, A., 1973. Las series del Paleozoico inferior y la estructura herciniana del occidente de Asturias (NO de España). Trabajos de Geología, 6, 1-113.
Martínez-Díaz, J.J., Capote, R., Tsige, M., Villamor, P., Martín-González, F., Insua-Arévalo, J.M., 2006. Seismic triggering in a stable continental area: The Lugo 1995 1997 seismic sequences (NW Spain). Journal of Geodynamics, 41(4), 440-449.
Martín-González, F., 2006. Tectónica alpina, neotectónica y sismotectónica en la terminación occidental de los relieves cantábricos (Noroeste del Macizo Ibérico): marco tectónico de las crisis sísmicas de Lugo. Doctoral Thesis. Madrid, Universidad Complutense de Madrid, 290pp.
McClusky, S., Reilinger, R., Mahmoud, S., Ben Sari, D., Tealeb, A., 2003. GPS constraints on Africa (Nubia) and Arabia plate motions. Geophysical Journal International, 155, 126-138.
Pascal, C., 2002. Interaction of faults and perturbation of slip: influence of anisotropic stress states in the presence of fault friction and comparison between Wallace–Bott and 3D Distinct Element models. Tectonophysics, 356, 307-322.
Pedreira, D., Pulgar, J.A., Gallart, J., Díaz, J., 2003. Seismic evidence of Alpine crustal thickening and wedging from the western Pyrenees to the Cantabrian Mountains (north Iberia). Journal of Geophysical Research, 108(B4), 2204. doi: 10.1029/2001JB001667
Pulgar, J.A., Gallart, J., Fernández-Viejo, G., Pérez-Estaún, A., Álvarez-Marrón, J., Group, E., 1996. Seismic image of the Cantabrian Mountains in the western extension of the Pyrenees from integrated ESCIN reflection and refraction data. Tectonophysics, 264, 1-19.
Pulgar, J., Alonso, J., Espina, R., Marín, J., 1999. La deformación alpina en el basamento varisco de la Zona Cantábrica. Trabajos de Geología, 21, 283-294.
Reasenberg, P., Oppenheimer, D., 1985. FPFIT, FPPLOT AND FPPAGE: fortran computer programs for calculating and displaying earthquake fault-plane solutions. U.S. Geological Survey, Open File Report, 85, 739.
Rueda, J., Mezcua, J., 2001. Sismicidad, Sismotectónica y Peligrosidad Sísmica en Galicia. Madrid, National Geographic Institute, Publication, 35, 64pp.
Serpelloni, E., Vannucci, G., Pondrelli, S., Argnani, A., Casula, G., Anzidei, M., Baldi, P., Gasperini, P., 2008. Kinematics of the Western Africa–Eurasia plate boundary from focal mechanisms and GPS data. Geophysical Journal International, 169, 1180-1200.
Stich, D., Serpelloni, E., Mancilla, F., Morales, J., 2006. Kinematics of the Iberia-Maghreb plate contact from seismic moment tensors and GPS observations. Tectonophysics, 426, 295-317.
Street, R., Bollinger, G., Woolery, E., 2002. Blasting and other mining-related activities in Kentucky: A source of earthquake misidentification. Seismological Research Letters, 73, 739-750.
Talwani, P., 1999. Fault geometry and earthquakes in continental interiors. Tectonophysics, 305, 371-379.
Waldhauser, F., 2001. HypoDD—a program to compute double-difference hypocenter locations. Open File Report, 01, 113.
Waldhauser, F., Ellsworth, W., 2000. A double-difference earthquake location algorithm: method and application to the northern Hayward fault. California. Bulletin of the Seismological Society of America, 90(6), 1353-1368.
Yamini-Fard, F., Hatzfeld, D., Mohammad, T., Mokhtari, M., 2006. Microearthquake seismicity at the intersection between the Kazerun fault and the Main Recent Fault (Zagros, Iran). Geophysical Journal International, 166, 186-196.
Downloads
Published
Issue
Section
License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Copyright
Geologica Acta is the property of the UB, GEO3BCN, IDAEA and UAB. Geologica Acta must be cited for any partial or full reproduction. Papers are distributed under the Attribution-Share Alike Creative Commons License. This license allows anyone to reproduce and disseminate the content of the journal and even make derivative works crediting authorship and provenance and distributing possible derivative works under the same or an equivalent license.
Author Rights
Authors retain the copyright on their papers and are authorized to post them on their own web pages or institutional repositories. The copyright was retained by the journal from the year 2003 until 2009. In all cases, the complete citation and a link to the Digital Object Identifier (DOI) of the article must be included.
The authors can use excerpts or reproduce illustrations of their papers in other works without prior permission from Geologica Acta provided the source of the paper including the complete citation is fully acknowledged.
