Depth‐Dependent Geometry of the Liquiñe‐Ofqui Fault Zone and Its Relation to Paths of Slab‐Derived Fluids

Abstract

Using a nonhomogeneous elastic model for the south Chile subduction zone, we calculate the depth-dependent geometry of the Liquiñe-Ofqui Fault Zone (LOFZ), considering that faults develop where shear stress is maximum. Shear stress develops due to the oblique subduction process, depending on shear modulus which varies as a function of the amount of fluids within the overriding plate. Regions with different values of shear modulus are obtained by the geometries of isotherms calculated from a thermal model. Based on the principle that fluids move from higher to lower pressure regions, we calculate paths of fluids from the subducting slab toward the free surface. In the vicinity of the volcanic arc, the obtained fluid paths agree with the geometry of the LOFZ, suggesting that margin-parallel strike-slip faults could serve as pathways for fluids through the overriding plate in oblique subduction zones.

Kinematic partitioning in the Southern Andes (39° S–46° S) inferred from lineament analysis and reassessment of exhumation rates

“…In the context of this tectonic framework, the LOFZ is commonly regarded as a subvertically dipping, narrow fault zone consisting of two NNEtrending lineaments that are connected through a number of step-over faults south of 43° S (Fig. 1; Lavenu and Cembrano 1999;Cembrano et al 2000Cembrano et al , 2002Catalán et al 2017).…”

Reactivating and Calming Volcanoes: The 2015 MW 8.3 Illapel Megathrust Strike

“…They were Nevados de Chillán (NdC), Copahue (COP), and Villarrica (VIL), located 581, 692, and 863 km away from the earthquake hypocenter, respectively. These volcanoes are located in a very active geological setting, where the right‐lateral strike‐slip Liquie‐Ofqui Fault System (LOFS; Pliocen/Holocene) and NW Andean Transverse Faults (Paleozoic/Triassic) are important geological features (Legrand et al., 2011; Sánchez et al., 2013), whose activity also has a large influence on the CSCVZ (Catalán et al., 2017; Cembrano & Lara, 2009; Cembrano et al., 1996; Stanton‐Yonge et al., 2016; Tardani et al., 2016). Figure 1 shows the geometry of the main fault systems for each volcano, based on several descriptions (Bonali et al., 2016; Cardona et al., 2018; Gonzalez‐Ferrán, 1995; Melnick et al., 2006; Meulle‐Stef et al., 2016; Moreno & Clavero, 2006), and also shows the rupture zones of the most recent historical earthquakes in the region (Ruiz & Madariaga, 2018).…”