Seismic Analysis of the 2020–2021 Santa Fe Seismic Sequence in the Granada Basin, Spain: Relocations and Focal Mechanisms

Lozano, Lucía; Cantavella, Juan Vicente; Gaite, Beatriz; Ruiz‐Barajas, Sandra; Antón, Resurrección; Barco, Jaime

doi:10.1785/0220220097

Cited by 6 publications

(5 citation statements)

References 53 publications

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“…The Granada Fault System is responsible for the 1431 Otura-Alhendín earthquake as well as the 1806 Pinos SW of Armilla and 1956 Albolote Earthquakes. This fault system also produced the 2021 Granada Seismic Swarm (Lozano et al, 2022;Madarieta-Txurruka et al, 2021, 2022. The Baza Fault is the seismogenic source of the 1531 Baza earthquake (I = VIII-IX, M ms = 6.0) (Alfaro et al, 2008).…”

Section: Geodynamic and Geological Settingmentioning

confidence: 98%

Insights of Active Extension Within a Collisional Orogen From GNSS (Central Betic Cordillera, S Spain)

et al. 2023

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The 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.

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Section: Geodynamic and Geological Settingmentioning

confidence: 98%

Insights of Active Extension Within a Collisional Orogen From GNSS (Central Betic Cordillera, S Spain)

et al. 2023

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“…The central Betic Cordillera (Figure 4) experiences shallow seismicity primarily located in the Granada Basin and the Campo de Dalías areas. The Granada Basin is characterized by recurrent low and low-to-moderate seismicity, with the occurrence of seismic series such as the 1988 Agrón series and the 2021 Santa Fe series [43,119,124]. Seismic activity is mainly concentrated in the eastern and southern edges.…”

Section: Seismological Data 421 Seismicitymentioning

confidence: 99%

“…This variety has been associated with a complex crustal structure and local permutation of stresses [43]. The Granada Basin is characterized by NW-SE normal faulting earthquakes, as evidenced by the 1984 earthquake and the 2021 seismic series (Figure 4) [43,124,127]. This sector is also characterized by focal mechanism solutions with NW-SE to N-S low-angle nodal planes [104].…”

Section: Earthquake Focal Mechanism Data and Current Stress Tensorsmentioning

confidence: 99%

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Active Collapse in the Central Betic Cordillera: Development of the Extensional System of the Granada Basin

et al. 2023

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The Betic Cordillera was formed by the collision between the Alboran Domain and the South Iberian paleomargin in the frame of the NW–SE convergent Eurasia–Nubia plate boundary. The central region is undergoing a heterogeneous extension that has not been adequately analysed. This comprehensive study addressed it by collecting structural geologic, seismologic, and geodetic data. The region west of the Sierra Nevada is deformed by the extensional system of the Granada Basin, which facilitates E–W to NE–SW extension. Moreover, the southern boundary of Sierra Nevada is affected by a remarkable N–S extension related to E–W normal to normal–dextral faults affecting the shallow crust. However, geologic and geodetic data suggest that the western and southwestern Granada Basin boundary constitutes a compressional front. These data lead to the proposal of an active extensional collapse from the uplifted Sierra Nevada region to the W–SW–S, over an extensional detachment. The collapse is determined by the uplift of the central Betics and the subsidence in the Alboran Basin due to an active subduction with rollback. Our results indicate that the central Betic Cordillera is a good example of ongoing extensional collapse in the general context of plate convergence, where crustal thickening and thinning simultaneously occur.

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“…The Betic Cordillera is currently affected by a NNW–SSE to NW–SE 4–6 mm/yr Eurasia‐Nubia convergence (DeMets et al., 2010; McClusky et al., 2003; Nocquet & Calais, 2003). At the same time, a nearly 2 mm/yr ENE–WSW extension perpendicular to regional compression occurs in the central Betic Cordillera (Galindo‐Zaldívar et al., 2015; Martín‐Rojas et al., 2023; Palano et al., 2015; Serpelloni et al., 2007), forming active high‐ and low‐angle normal faults (Galindo‐Zaldívar et al., 1999; Lozano et al., 2022; Madarieta‐Txurruka et al., 2021, 2022; Sanz de Galdeano et al., 2003). Today, the Granada Basin is the main extensional active basin of the central Betic Cordillera (Morales et al., 1990; Rodríguez‐Fernández & Sanz de Galdeano, 2006).…”

Section: Introductionmentioning

confidence: 99%

Active Shortening Simultaneous to Normal Faulting Based on GNSS, Geophysical, and Geological Data: The Seismogenic Ventas de Zafarraya Fault (Betic Cordillera, Southern Spain)

Madarieta‐Txurruka,

González‐Castillo,

Peláez

et al. 2024

Tectonics

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The 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.

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Seismic Analysis of the 2020–2021 Santa Fe Seismic Sequence in the Granada Basin, Spain: Relocations and Focal Mechanisms

Cited by 6 publications

References 53 publications

Insights of Active Extension Within a Collisional Orogen From GNSS (Central Betic Cordillera, S Spain)

Insights of Active Extension Within a Collisional Orogen From GNSS (Central Betic Cordillera, S Spain)

Active Collapse in the Central Betic Cordillera: Development of the Extensional System of the Granada Basin

Active Shortening Simultaneous to Normal Faulting Based on GNSS, Geophysical, and Geological Data: The Seismogenic Ventas de Zafarraya Fault (Betic Cordillera, Southern Spain)

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