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| Titel |
Fine fault structure of the 2012-2013 earthquake swarm in the eastern Guadalquivir basin (South Spain) |
| VerfasserIn |
José Morales, Juan V. Cantavella, José V. Perez-Peña, Rosa Martín, Daniel Stich, José M. Azañon, Antonio Gonzalez-Ramón, Francisco J. Roldán, José B. Martín |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089489
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| Publikation (Nr.) |
 EGU/EGU2014-3693.pdf |
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| Zusammenfassung |
| Seismic swarms in areas with low seismic activity offer valuable information on the stress
regimen from often-unidentified tectonic structures. From October 20th 2012 to end of
October 2013, a seismic swarm with more than 6500 located earthquakes took place
near the village of Torreperogil in the Eastern Guadalquivir basin. We relocate 523
events (md >1.5) using the double difference algorithm, in order to image the active
structures associated with this swarm. Relocation places most events at 4-6.5 km depth
along to two separate, steep dipping, ~N-S trending lineaments at ~1 km distance,
with the western lineament becoming active more than 2 months after the start
of the swarm. The Hough algorithm indicates a direction of N173E for the main
alignment, similar to the result from full waveform moment tensor inversion for the large
earthquake, yielding a strike slip mechanism with NS striking left-lateral plane.
The results draw a scenario of ~N-S left-lateral blind faults in a highly fractured
volume of the Variscan basement underlying the basin, consistent with a ~NNW
direction of the principal compressive stress in the central Betics. The strike slip
faulting style is compatible with an inactive mountain front in this sector, but the
simultaneous activity of these side-by-side faults is not straightforward to understand
in terms of stress transfer. We found no evidence for triggering of this sequence,
investigating as possible mechanisms the pore pressure variations by hydraulic
diffusion from rainwater, variations in elastic loading following the fluctuations
in the water table of aquifers, as well as triggering by large remote earthquakes. |
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