Slip rate of trench‐parallel normal faulting along the Mejillones Fault (Atacama Fault System): Relationships with the northern Chile subduction and implications for seismic hazards

J.F. Ritz (1) , Regis Braucher (2) , Didier Bourlès (2) , Bertrand Delouis (3) , Carlos Marquardt (4) , Alain Lavenu (5) , Hervé Philip (1) , Luc Ortlieb (6, 7)

1 Géosciences Montpellier
2 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
3 Géosciences Azur
4 UC - Pontificia Universidad Católica de Chile
5 GET - Géosciences Environnement Toulouse
6 IRD - Institut de Recherche pour le Développement
7 LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques

The recent tectonics of the arid northern Chile Andean western forearc is characterized by trench‐parallel normal faults within the Atacama Fault System (AFS). Since the 1995‐Mw 8.1 Antofagasta earthquake, the mechanism driving this recent and localized extension is considered to be associated with the seismic cycle within the subduction zone. Analyzing morphotectonic patterns along these faults allows examining the seismic potential associated with the subduction zone. Using field Digital Elevation Models and in situ‐produced cosmogenic 10Be, we determined a 0.2 mm/a long‐term slip rate along the Mejillones Fault, one of the most prominent structures within the AFS. This result suggests that the AFS corresponds to slow slip rate faults despite the rapid subduction context. However, the size of coseismic slips observed along the AFS faults suggests that larger subduction earthquakes (Mw > 8.1) may occur episodically in the area.

Keywords: SITU-PRODUCED BE-10; RANGE GOBI-ALTAY; 7.7 TOCOPILLA EARTHQUAKE; CRUSTAL DEFORMATION; HALF-LIFE; ANTOFAGASTA; GPS; SEGMENTATION

Keywords: COASTAL CORDILLERA; PLATE

Domains: Sciences of the Universe [physics]; Earth Sciences; Tectonics

J.F. Ritz, Regis Braucher, Didier Bourlès, Bertrand Delouis, Carlos Marquardt, et al.. Slip rate of trench‐parallel normal faulting along the Mejillones Fault (Atacama Fault System): Relationships with the northern Chile subduction and implications for seismic hazards. Terra Nova, 2019, 31 (4), pp.390-404. ⟨10.1111/ter.12401⟩. ⟨hal-03089548⟩