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Article Dans Une Revue Geophysical Journal International Année : 2021

Northern Chile intermediate-depth earthquakes controlled by plate hydration


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 7-30 MPa. Conversely, aftershocks productivity systematically decreases for the deeper events within the slab. Particularly there is a dramatic decrease in aftershock activity below the 400-450 ºC 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 700-800ºC 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.
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hal-03197367 , version 1 (13-04-2021)



Leoncio Cabrera, Sergio Ruiz, Piero Poli, Eduardo Contreras-Reyes, Axel Osses, et al.. Northern Chile intermediate-depth earthquakes controlled by plate hydration. Geophysical Journal International, 2021, 226 (1), pp.78-90. ⟨10.1093/gji/ggaa565⟩. ⟨hal-03197367⟩
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