Slip partitioning in the 2016 Alboran Sea earthquake sequence (western Mediterranean)
- AM(W)= 5.1 earthquake on January 21st, 2016 marked the beginning of a significant seismic sequence in the southern Alboran Sea, culminating in aM(W)= 6.3 earthquake on January 25th, and continuing with further moderate magnitude earthquakes until March. We use data from 35 seismic broadband stations in Spain, Morocco and Portugal to relocate the seismicity, estimate seismic moment tensors, and isolate regional apparent source time functions for the main earthquake. Relocation and regional moment tensor inversion consistently yield very shallow depths for the majority of events. We obtain 50 moment tensors for the sequence, showing a mixture of strike-slip faulting for the foreshock and the main event and reverse faulting for the major aftershocks. The leading role of reverse focal mechanisms among the aftershocks may be explained by the geometry of the fault network. The mainshock nucleates at a bend along the left-lateral Al-Idrisi fault, introducing local transpression within the transtensional Alboran Basin. The shallow depths ofAM(W)= 5.1 earthquake on January 21st, 2016 marked the beginning of a significant seismic sequence in the southern Alboran Sea, culminating in aM(W)= 6.3 earthquake on January 25th, and continuing with further moderate magnitude earthquakes until March. We use data from 35 seismic broadband stations in Spain, Morocco and Portugal to relocate the seismicity, estimate seismic moment tensors, and isolate regional apparent source time functions for the main earthquake. Relocation and regional moment tensor inversion consistently yield very shallow depths for the majority of events. We obtain 50 moment tensors for the sequence, showing a mixture of strike-slip faulting for the foreshock and the main event and reverse faulting for the major aftershocks. The leading role of reverse focal mechanisms among the aftershocks may be explained by the geometry of the fault network. The mainshock nucleates at a bend along the left-lateral Al-Idrisi fault, introducing local transpression within the transtensional Alboran Basin. The shallow depths of the 2016 Alboran Sea earthquakes may favor slip-partitioning on the involved faults. Apparent source durations for the main event suggest a similar to 21 km long, asymmetric rupture that propagates primarily toward NE into the restraining fault segment, with fast rupture speed of similar to 3.0 km/s. Consistently, the inversion for laterally variable fault displacement situates the main slip in the restraining segment. The partitioning into strike-slip rupture and dip-slip aftershocks confirms a non-optimal orientation of this segment, and suggests that the 2016 event settled a slip deficit from previous ruptures that could not propagate into the stronger restraining segment.…
Author details: | Daniel StichORCiD, Rosa Martin, Jose Morales, Jose Angel Lopez-CominoORCiD, Flor de Lis Mancilla |
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DOI: | https://doi.org/10.3389/feart.2020.587356 |
ISSN: | 2296-6463 |
Title of parent work (English): | Frontiers in Earth Science |
Publisher: | Frontiers Media |
Place of publishing: | Lausanne |
Publication type: | Article |
Language: | English |
Date of first publication: | 2020/09/29 |
Publication year: | 2020 |
Release date: | 2022/10/10 |
Tag: | fault bend; moment tensor; shallow earthquakes; slip partitioning; source time function |
Volume: | 8 |
Article number: | 587356 |
Number of pages: | 19 |
Funding institution: | FEDER/MINECO [CGL2015-67130-C2-2-R, PID2019-109608GB-I00]; FEDER/Junta; de Andalucia project [A-RNM-421-UGR18]; Junta de AndaluciaJunta de; Andalucia [RNM104]; European UnionEuropean Commission [754446]; UGR; Research and Knowledge Transfer Found-Athenea3i of the Deutsche; Forschungsgemeinschaft (DFG, German Research Foundation)German Research; Foundation (DFG) [407141557] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
DDC classification: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer review: | Referiert |
Publishing method: | Open Access / Gold Open-Access |
DOAJ gelistet | |
License (German): | CC-BY - Namensnennung 4.0 International |