RT Journal Article
T1 High resolution seismic imaging of an active fault in the eastern Guadalquivir Basin (Betic Cordillera, Southern Spain)
A1 Serrano, Inmaculada
A1 Torcal Medina, Federico
A1 Benito Martín, José
K1 Seismic tomography
K1 Seismicity and tectonics
K1 Crustal structures
K1 Fractures and faults
K1 Active tectonics
K1 Guadalquivir Basin
AB AbstractWe calculated the high resolution seismic velocity, Poisson's ratio, crack density and saturation ratio structures in and around the source areas of the Torreperogil seismic series (October 2012–April 2013). This seismic series, characterized by a large number of low magnitude (below Mw 3.7 or Md 3.9) and very shallow microearthquakes, took place in the Guadalquivir Basin, a large flexural foreland basin with a linear ENE–WSW trending bounded to the north by the Iberian Massif and to the south by the Betic Cordillera and filled from a middle Miocene to Plio–Quaternary sedimentary sequence.In the upper layers of the crust, strong low-velocity anomalies are extensively distributed under the central zone, which together with high Poisson's ratio and crack density values may correspond to rocks which are less likely to fracture, perhaps due to the accumulation of tectonic and seismic stress. 93% of the earthquakes occurred at depths of up to 8 km, which could indicate that the base of the seismogenic zone lies at this depth. The seismic series was concentrated in layers of strong structural heterogeneities (in the boundary area between low and high anomalies), which were likely to generate earthquakes due to differential strain accumulation beneath the region. The high velocity areas are also considered to be strong yet brittle parts of the fault zone, which may generate earthquakes (at depths of between 5 km and 9 km). By contrast, low velocity areas are less prone to fracture, allowing seismic slippage to take place (from 2 to 4 km depth).The best estimate of the depth of the main shock (mbLg 3.9) is 7.6 km, which could tend to nucleate at the base of the seismogenic zone, at the “fault end” on the boundary between a low velocity zone to the east and a high velocity zone to the west, indicating the fault plane which separates both areas laterally. Assuming that this seismic contrast is one of the main Torreperogil faults it could imply that stress has accumulated in an existing fault zone with lateral heterogeneity in velocity.
PB Elsevier
YR 2015
FD 2015-09-07
LK https://hdl.handle.net/10433/26372
UL https://hdl.handle.net/10433/26372
LA en
NO Tectonophysics Volume 660, 7 October 2015, Pages 79-91
NO Proyectos de investigaciónThis work has been supported by the Comisión Interministerial de Ciencia y Tecnología CICYT (Spain) projects with references CGL2012-31472 (Estructura cortical y litosférica en el Sector Central de la Cordillera Bética y su transicion al Macizo Varisco. Sismotectónica del sur-sureste de la Península Ibérica), CGL2013-46368-P (Localización de la deformación en convergencia oblicua y cuencas tardiorogénicas: estudio multidisciplinar de casos (Béticas) y modelización); Proyectos de Excelencia de la Junta de Andalucía (Spain) P09-RNM-5100 (Estructura 3D del Arco de Gibraltar y modelado numérico de la propagación de ondas sísmicas de terremotos en la zona de contacto de placa Nubia-Eurasia) and RNM-451 (Evolución reciente de los contactos principales entre dominios estructurales/reológicos del Sistema del Arco de Gibraltar: estudios integrados tierra-mar); and Grupo de Investigación de la Junta de Andalucía (Spain) RNM-104, Sismología y Geofísica.
NO Instituto Universitario de Investigación Andaluz de Geofísica y Prevención de Desastres Sísmicos,
NO Departamento de Física Teórica y del Cosmos, Facultad de Ciencias, Universidad de Granada
NO Universidad Pablo de Olavide. Departamento de Sistemas Físicos, Químicos y Naturales
DS RIO
RD May 22, 2026