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We investigate the variations of the seismic source properties and aftershock activity using kinematic inversions and template-matching for six large magnitude intermediate-depth earthquakes occurred in northern Chile. Results show similar rupture geometry and stress drop values between 7 and 30 MPa. Conversely, aftershock productivity systematically decreases for the deeper events within the slab. Particularly, there is a dramatic decrease in aftershock activity below the 400–450 °C isotherm depth, which separates high- and low-hydrated zones. The events exhibit tensional focal mechanisms at unexpected depths within the slab, suggesting a deepening of the neutral plane, where the extensional regimen reaches the 700–800 °C isotherm depth. We interpret the reduction of aftershocks in the lower part of the extensional regime as the absence of a hydrated-slab at those depths. Our finding highlights the role of the thermal structure and fluids in the subducting plate in controlling the intermediated-depth seismic activity and shed new light in their causative mechanism. [ABSTRACT FROM AUTHOR]

A magnetotelluric study was carried out in the San Pedro‐Linzor volcanic chain, North Chile, to identify possible magmatic structures and hydrothermal systems associated with volcanoes of Holocene activity, considering previous petrochemical studies pointing to crystallization depths of approximately 8 km. Three‐dimensional resistivity models based on magnetotellurics data of the San Pedro‐Linzor volcanic chain were obtained based on broadband data measured in 2017 and 2018, in addition to long‐period data measured in 1990s. The three‐dimensional modeling shows two low‐resistivity zones (less than 10 Ωm) interpreted as partially molten areas below the Chao Dome and the Paniri volcano, and a shallower low resistivity area (less than 5 Ωm) in the Turi Basin, an active hydrothermal system to the southwest of the volcanic chain. Key Points: Magnetotellurics have been used to image the conductivity distribution below a volcanic chain in the Central AndesMagmatic and hydrothermal structures associated with diverse volcanic products along the chain have been inferred3‐D modeling tools were used considering strong topographic variations of more than 1 km in some areas [ABSTRACT FROM AUTHOR]