Preprints
https://doi.org/10.5194/egusphere-2023-2401
https://doi.org/10.5194/egusphere-2023-2401
28 Nov 2023
 | 28 Nov 2023

Palaeoseismic crisis in the Galera Fault (S Spain). Consequences in Bronze Age settlements?

Ivan Martin-Rojas, Ivan Medina-Cascales, Francisco Juan García-Tortosa, Maria Oliva Rodríguez-Ariza, Fernando Molina González, Juan Antonio Cámara Serrano, and Pedro Alfaro

Abstract. Palaeoseismological studies play a crucial role in the seismic characterization of regions with slow moving faults. This is the case of the Central Betic Cordillera, a highly populated area where the record of prehistoric earthquakes is very scarce, despite of being one of the regions with the highest seismic hazard in Spain.

We present here a palaeoseismological characterization of the Galera Fault, one of the active faults accommodating deformation in the Central Betic Cordillera. We excavated and analysed several trenches along the fault trace. We quantitatively correlate the results from these trenches, resulting in a surface rupture history involving 7 or 8 events (accounting for the epistemic uncertainties) during the last ca. 24000 yr, with a recurrence interval ranging between 1520 and 1720 yr. Further analysis of this surface rupture history seems to indicate that the Galera Fault is prone to produce earthquakes clusters, as we recorded five events in ca. 400 yr (ca. 1536–1126 BC), and only two events in the next ca. 3200 yr.

Using the fault geometry and palaeoseismological data, we also carried out a seismogenic characterization of the fault. This analysis yielded a maximum expected magnitude of 6.7 ± 0.3 and a recurrence interval of 1857 yr. Furthermore, we also present a geodetic rupture scenario for the maximum expected event, involving displacements of up to 0.5 m.

Finally, we discuss the possible impact of the deduced palaeoearthquakes in the development of Bronze Age human settlements located in the vicinity of the fault. Other than their intrinsic value, our results will be the basis for future seismic hazard assessment carried out in the Central Betic Cordillera.

Ivan Martin-Rojas, Ivan Medina-Cascales, Francisco Juan García-Tortosa, Maria Oliva Rodríguez-Ariza, Fernando Molina González, Juan Antonio Cámara Serrano, and Pedro Alfaro

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2401', Anonymous Referee #1, 29 Dec 2023
  • RC2: 'Comment on egusphere-2023-2401', Anonymous Referee #2, 07 Feb 2024
Ivan Martin-Rojas, Ivan Medina-Cascales, Francisco Juan García-Tortosa, Maria Oliva Rodríguez-Ariza, Fernando Molina González, Juan Antonio Cámara Serrano, and Pedro Alfaro
Ivan Martin-Rojas, Ivan Medina-Cascales, Francisco Juan García-Tortosa, Maria Oliva Rodríguez-Ariza, Fernando Molina González, Juan Antonio Cámara Serrano, and Pedro Alfaro

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Short summary
We investigated the prehistoric earthquakes produced by the Galera Fault (S Spain) during the las 24000 years. We deduced from these analysis the basic parameters that permit to characterize the seismic hazard of this fault. Furthermore, we discuss how the Galera Fault is prone to produce seismic crisis. We also propose that one of these crises could have been responsable for the abandonment of Bronze Age human settlements located near the fault.