Examinando por Autor "Madarieta-Txurruka, Asier"
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Ítem Active Shortening Simultaneous to Normal Faulting Based on GNSS, Geophysical, and Geological Data: The Seismogenic Ventas de Zafarraya Fault (Betic Cordillera, Southern Spain)(Willey, 2024) Madarieta-Txurruka, Asier; González-Castillo, Lourdes; Peláez, José Antonio; Galindo, Jesús; Borque, María Jesús; de-Lacy, Maria Clara; Ruiz-Armenteros, Antonio Miguel; Henares, Jesús; Ruano, Patricia; Sánchez-Alzola, Alberto; Avilés-Moreno, Manuel; Rodríguez-Caderot, Gracia; Martínez-Moreno, Francisco José; Tendero-Salmerón, Víctor; Vinardell-Peña, Raquel; Gil-Cruz, Antonio JoséThe central Betic Cordillera, southern Spain, is affected by an uplift related to the NNW–SSE Eurasia-Nubia convergence and shallow ENE–WSW orthogonal extension accommodated by the extensional system of the Granada Basin. The combination of geophysical, geodetic, and geological data reveals that the southwestern boundary of this extensional system is a seismically active compressional front extending from the W to the SW of the Granada Basin. The near-field Global Navigation Satellite System data determine NNE–SSW shortening of up to 2 mm/yr of the compressional front in the Zafarraya Polje. In this setting, the normal Ventas de Zafarraya Fault developed as a result of the bending-moment extension of the Sierra de Alhama antiform and was last reactivated during the 1884 Andalusian earthquake (Mw 6.5). The uplift in the central Betic Cordillera together with the subsidence in the Western Alborán Basin may facilitate a westward to southwestward gravitational collapse through the extensional detachment of the Granada Basin. The heterogeneous crust of the Betic Cordillera would generate the compressional front, which is divided into two sectors: thrusting to the west, and folding associated with buttressing to the south. Our results evidence that basal detachments, linking extensional fault activity with compressional fronts, may determine the activity of local surface structures and the geological hazard in densely populated regions.Ítem High- and Low-Angle Normal Fault Activity in a Collisional Orogen: The Northeastern Granada Basin (Betic Cordillera)(Willey, 2021) Madarieta-Txurruka, Asier; Galindo, Jesús; González-Castillo, Lourdes; Peláez, José Antonio; Ruiz-Armenteros, Antonio Miguel; Henares, Jesús; Garrido-Carretero, María Selmira; Avilés-Moreno, Manuel; Gil-Cruz, Antonio JoséUnderstanding active tectonics and seismicity in extensional settings requires the analysis of high-angle normal faults (HANFs) and the transfer of deformation at depth. The debate surrounds the role of low-angle normal faults (LANFs) in triggering high magnitude earthquakes. The central Betic Cordillera is an active seismic zone affected by the NNW-SSE Eurasia-Nubia convergence and orthogonal extension. The seismicity and present-day stress determined by earthquake focal mechanisms reveals the activity of a NE-SW extensional system in the shallowest 12 km of the Granada Basin. The structure of the sedimentary infill, as derived by geological field and gravimetric techniques, suggests the formation of a half-graben tilted to the N-NE. Seismologic data suggest the activity of HANFs above 6–7 km depth and a LANF zone around 6–12 km depth, with related earthquakes of up to Mw 4.0 and 20° to 30° fault dips. High-precision leveling lines highlight the importance of the Granada Fault in the system, with average vertical displacement rates of 0.35–1.1 mm/yr. These data suggest creep fault behavior at the surface and increased seismicity at depth. The upper crustal extension in the collisional Betic Cordillera is accommodated by a top-to-the-WSW extensional detachment related to westward motion and rollback in the Gibraltar Arc and the gravitational collapse of the cordillera, in a framework of NNW-SSE shortening. This comprehensive study draws a new scenario that advances understanding of relationships between HANFs and LANFs.Ítem Insights of Active Extension Within a Collisional Orogen From GNSS (Central Betic Cordillera, S Spain)(Whiley, 2023-06-13) Martín-Rojas, Iván; Alfaro, Pedro; Galindo, Jesús; Borque, María Jesús; García-Tortosa, Francisco Juan; Sanz-de Galdeano, Carlos; Avilés-Moreno, Manuel; Sánchez-Alzola, Alberto; González-Castillo, Lourdes; Ruano, Patricia; Medina-Cascales, Iván; Tendero-Salmerón, Víctor; Madarieta-Txurruka, Asier; Pedrosa-González, María Teresa; Gil-Cruz, Antonio JoséThe coexistence of shortening and extensional tectonic regimes is a common feature in orogenic belts. The westernmost end of the Western Mediterranean is an area undergoing shortening related to the 5 mm/yr NNW‒SSE convergence of the Nubia and Eurasia Plates. In this region, the Central Betic Cordillera shows a regional ENE‒WSW extension. Here, we present GNSS-derived geodetic data along a 170 km-long transect orthogonal to the main active normal faults of the Central Betic Cordillera. Our data indicate that the total extension rate along the Central Betic Cordillera is 2.0 ± 0.3 mm/yr. Extension is accommodated in the eastern (0.8 ± 0.3 mm/yr in the Guadix-Baza Basin) and western (1.3 ± 0.3 mm/yr in the Granada Basin) parts of the Central Betic Cordillera, while no extension is recorded in the central part of the study area. Moreover, our data permit us to quantify, for the first time, short-term fault slip rates of the Granada Fault System, which is one of the main seismogenic sources of the Iberian Peninsula. We deduce a fault slip rate of ∼1.3 ± 0.3 mm/yr for the whole Granada Basin, with 0.9 ± 0.3 mm/yr being accommodated in the Granada Fault System and 0.4 ± 0.3 mm/yr being accommodated in the southwestern sector of the Granada Basin, where no active faults have been previously described at the surface. The heterogeneous extension in the Central Betic Cordillera could be accommodated by shallow high-angle normal faults that merge with a detachment at depth. Part of the active extension could be derived from gravitational instability because of underlying over-thickened crust.Ítem The Campo de Dalias GNSS Network Unveils the Interaction between Roll-Back and Indentation Tectonics in the Gibraltar Arc(MDPI, 2022-03-09) Galindo, Jesús; Gil-Cruz, Antonio José; Tendero-Salmerón, Víctor; Borque, María Jesús; Ercilla, Gemma; González-Castillo, Lourdes; Sánchez-Alzola, Alberto; de-Lacy, María Clara ; Estrada, Ferran; Avilés-Moreno, Manuel; Alfaro, Pedro; Madarieta-Txurruka, Asier; Chacón, FernandoThe Gibraltar Arc includes the Betic and Rif Cordilleras surrounding the Alboran Sea; it is formed at the northwest-southeast Eurasia–Nubia convergent plate boundary in the westernmost Mediterranean. Since 2006, the Campo de Dalias GNSS network has monitored active tectonic deformation of the most seismically active area on the north coast of the Alboran Sea. Our results show that the residual deformation rates with respect to Eurasia range from 1.7 to 3.0 mm/year; roughly homogenous west-southwestward displacements of the northern sites occur, while the southern sites evidence irregular displacements towards the west and northwest. This deformation pattern supports simultaneous east-northeast–west-southwest extension, accommodated by normal and oblique faults, and north-northwest-south-southeast shortening that develops east-northeast–west-southwest folds. Moreover, the GNSS results point to dextral creep of the main northwest–southeast Balanegra Fault. These GNNS results thus reveal, for the first time, the present-day interaction of the roll-back tectonics of the Rif–Gibraltar–Betic slab in the western part of the Gibraltar Arc with the indentation tectonics affecting the eastern and southern areas, providing new insights for improving tectonic models of arcuate orogens.