Main features of the deep structure by local earthquake tomography and active tectonics: case of Rif Mountain (morocco) and Betic Cordillera (Spain)

Timoulali, Youssef; Hahou, Youssef; Jabour, Nacer; Merrouch, Redouane; Kharrim, A. El

doi:10.1007/s10950-013-9385-0

Cited by 6 publications

(1 citation statement)

References 49 publications

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“…1 and Table 1), the present-day tectonic framework of the Al Hoceima region is dominated by a strike-slip fault regime where moment magnitudes do not exceed 6.5. Limited fault-rupture dimensions are likely due to the local structural geology made of overthrusting nappes on highly deformed continental crustal rocks (Chalouan et al 2008;Timoulali et al 2014). Because of the limited number of local seismic stations in the Rif, the location of aftershocks of the 1994 and offshore 2016 earthquakes are poorly resolved, which is not the case for the 2004 earthquake (Tahayt et al 2009).…”

Section: S E I S M O T E C T O N I C S E T T I N Gmentioning

confidence: 99%

The Al Hoceima earthquake sequence of 1994, 2004 and 2016: Stress transfer and poroelasticity in the Rif and Alboran Sea region

Kariche

Meghraoui²,

Timoulali

et al. 2017

Geophysical Journal International

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The 2016 January 25 earthquake (M w 6.3) follows in sequence from the1994 May 26 earthquake (M w 6.0) and the 2004 February 24 earthquake (M w 6.4) in the Rif Mountains and Alboran Sea. The earlier two seismic events which were destructive took place on inland conjugate faults, and the third event occurred on an offshore fault. These earthquake sequences occurred within a period of 22 yr at ∼25 km distance and 11-16-km depth. The three events have similar strike-slip focal mechanism solutions with NNE-SSW trending left-lateral faulting for the 1994 and 2016 events and NW-SE trending right-lateral faulting for the 2004 event. This shallow seismic sequence offers the possibility (i) to model the change in Coulomb Failure Function (CFF with low μ including the pore pressure change) and understand fault-rupture interaction, and (ii) to analyse the effect of pore fluid on the rupture mechanism, and infer the clock-time advance. The variation of static stress change has a direct impact on the main shock, aftershocks and related positive lobes of the 2004 earthquake rupture with a stress change increase of 0.7-1.1 bar. Similarly, the 2004 main shock and aftershocks indicate loading zones with a stress change (>0.25 bar) that includes the 2016 earthquake rupture. The tectonic loading of 19-24 nanostrain yr −1 obtained from the seismicity catalogue of Morocco is comparable to the 5.0 × 10 17 N•m yr −1 seismic strain release in the Rif Mountains. The seismic sequence is apparently controlled by the poroelastic properties of the seismogenic layer that depend on the undrained and drained fluid conditions. The short interseismic period between main shocks and higher rate of aftershocks with relatively large magnitudes (4 < M w < 5.5) implies the pore-fluid physical effect in undrained and drained conditions. The stress-rate ranges between 461 and 582 Pa yr −1 with a CFF of 0.2-1.1 bar. The computed clock-time advance reaches 239 ± 22 yr in agreement with the ∼10 yr delay between main shocks. The calculated static stress change of 0.9-1.3 bar, under pore-fluid stimulus added with well-constrained geodetic and seismic strain rates are critical for any seismic hazard assessment.

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Section: S E I S M O T E C T O N I C S E T T I N Gmentioning

confidence: 99%