Fig. 1

Study area. A regional map shows the morphostructural units delimited by black dashed lines and volcanoes are represented by yellow triangles, the volcanic arc is defined by the location of these volcanoes. The location of the 2010 M8.8 Maule earthquake epicenter is shown as a red star. A map inset shows the MT study area. Broadband MT stations are shown in circles: green represents those measured by Alterra Power (2009–2012), yellow by Universidad de Chile and University of Alberta (2015–2016). The red circles are the stations used in the 2D inversion. The profile used in the 2D inversion is denoted by AA′. MGS is delimited in black by the MT anomaly from Hickson et al. (2011). The faults shown are (1) fault mapped by Sernageomin (2003) using surface features and (2) reverse east-verging faults, from west to east: García Fault, Las Corrientes Fault and Hornitos Fault (Astaburuaga 2014)