An exceptionally long paleoseismic record of a slow-moving fault: The Alhama de Murcia fault (Eastern Betic shear zone, Spain)



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Ortuño, María and Masana, Eulàlia and García Meléndez, Eduardo and Martínez Díaz, José J. and Štěpančíková, Petra and Cunha, Pedro P. and Sohbati, Reza and Canora Catalán, Carolina and Buylaert, Jan Pieter and Murray, Andrew S. (2012) An exceptionally long paleoseismic record of a slow-moving fault: The Alhama de Murcia fault (Eastern Betic shear zone, Spain). Geological Society of America Bulletin, 124 (9-10). pp. 1474-1494. ISSN 0016-7606 , 1943-2674

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Most catastrophic earthquakes occur along fast-moving faults, although some of them are triggered by slow-moving ones. Long paleoseismic histories are infrequent in the latter faults. Here, an exceptionally long paleoseismic record (more than 300 k.y.) of a slow-moving structure is presented for the southern tip of the Alhama de Murcia fault (Eastern Betic shear zone), which is characterized by morphological expression of current tectonic activity and by a lack of historical seismicity. At its tip, the fault divides into a splay with two main faults bounding the Góñar fault system. At this area, the condensed sedimentation and the distribution of the deformation in several structures provided us with more opportunities to obtain a complete paleoseismic record than at other segments of the fault. The tectonic deformation of the system was studied by an integrated structural, geomorphological, and paleoseismological approach. Stratigraphic and tectonic features at six paleoseismic trenches indicate that old alluvial units have been repeatedly folded and thrusted over younger ones along the different traces of the structure. The correlation of the event timing inferred for each of these trenches and the application of an improved protocol for the infrared stimulated luminescence (IRSL) dating of K-feldspar allowed us to constrain a paleoseismic record as old as 325 ka. We identified a minimum of six possible paleo of Mw = 6–7 and a maximum mean recurrence interval of 29 k.y. This provides compelling evidence for the underestimation of the seismic hazard in the region.

Item Type:Article
Uncontrolled Keywords:Paleoseismic; Eastern Betic
Subjects:Sciences > Geology > Geodynamics
Sciences > Geology > Seismology
ID Code:65204
Deposited On:07 May 2021 06:43
Last Modified:07 May 2021 11:09

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