RT Journal Article
T1 Azimuthal seismic anisotropy in the crust beneath the Granada Basin (Spain)
A1 Serrano, Inmaculada
A1 Dengra, Miguel Ángel
A1 Torcal Medina, Federico
A1 Zhao, Dapeng
K1 Seismic tomography
K1 Seismic anisotropy
K1 Earthquake
K1 Fault
K1 Atarfe-Santa Fe seismic series
K1 Betic Cordillera
AB AbstractIn this research, we conducted the first P-wave tomographic imaging of 3-D azimuthal anisotropy of the Granada Basin (Betic Cordillera, Spain) introducing recent advances in the application of this method, thanks to abundant, high-quality data sets recorded by a dense seismic network deployed in the study area during the Atarfe-Santa Fe seismic series (2020−2021). We also determined high-resolution P- and S- wave tomography for 3-D isotropy of the study area down to 14 km depth and then the three-dimensional distributions of Poisson's ratio (σ). The result for the uppermost crust reveals the lower velocities associated with the predominantly Neogene-Quaternary sediments in the Basin. During the Atarfe-Santa Fe seismic series there were five earthquakes with a magnitude of over 4.1. In the source areas of the first of these earthquakes, significant variations were detected in P-velocities and high Poisson's ratios. This suggests that fluids might be involved in the nucleation and development of the seismic sequence. The fast polarization directions (NE-SW) in the central study area are mostly parallel to the Cadiz-Alicante fault system and almost perpendicular to the NW-SE fault plane directions obtained from the focal mechanism solutions for the earthquakes with the largest magnitudes, which present a clearly NE-SW extensional model. At the end of the middle Miocene, the Cadiz-Alicante fault system was practically immobilized, and an approximate NNW-SSE compression with a perpendicular extension, which was strongly pronounced in the Granada basin, was established. This extension is now active. Our results could therefore be suggesting that extension tectonics is the dominant effect in the upper crustal depth, as reflected by a significant NE-SW Fast Velocity Direction (FVD). Another possibility is that the FVD may have continued unchanged since the end of the middle Miocene due to the control exerted by the Cadiz-Alicante fault system, indicating structure-induced crustal anisotropy.
PB Elsevier
YR 2024
FD 2024-07-09
LK https://hdl.handle.net/10433/26374
UL https://hdl.handle.net/10433/26374
LA en
NO Tectonophysics Volume 882, 9 July 2024, 230360
NO Proyectos de investigaciónThis work has been funded by the following projects: “Visualización de modelos sísmicos temporales generados a partir de la integración de los tiempos de viaje de los terremotos registrados en Andalucía (Junta de Andalucía, P20_00694), PID2019-109608GB-100 from Spanish Research agency MCIN/AEI/ 10.13039/501100011033 and IMAGMASEIS: PID2021-124381NB-C2 from Spanish Research agency MCIN/AEI.
NO Universidad Pablo de Olavide. Departamento de Sistemas Físicos, Químicos y Naturales
NO Instituto Andaluz de Geofísica, Universidad de Granada, Spain
NO Departamento de Física Teórica y del Cosmos, Facultad de Ciencias, Granada, Spain
NO Universidad Pablo de Olavide. Departamento de Sistemas Físicos, Químicos y Naturales
NO Tohoku University, Sendai, Japan
DS RIO
RD May 22, 2026