Crustal faults in the Chilean Andes: geological constraints and seismic potential

ABSTRACT The Chilean Andes, as a characteristic tectonic and geomorphological region, is a perfect location to unravel the geologic nature of seismic hazards. The Chilean segment of the Nazca-South American subduction zone has experienced mega-earthquakes with Moment Magnitudes (Mw) >8.5 (e.g., M...

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Autores principales:	Santibáñez,Isabel, Cembrano,José, García-Pérez,Tiaren, Costa,Carlos, Yáñez,Gonzalo, Marquardt,Carlos, Arancibia,Gloria, González,Gabriel
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2019
Materias:	Crustal Faults Seismic Hazard Neotectonics Crustal earthquakes Paleoseismology Chilean Andes
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062019000100032
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spelling	oai:scielo:S0718-710620190001000322019-02-18Crustal faults in the Chilean Andes: geological constraints and seismic potentialSantibáñez,IsabelCembrano,JoséGarcía-Pérez,TiarenCosta,CarlosYáñez,GonzaloMarquardt,CarlosArancibia,GloriaGonzález,Gabriel Crustal Faults Seismic Hazard Neotectonics Crustal earthquakes Paleoseismology Chilean Andes ABSTRACT The Chilean Andes, as a characteristic tectonic and geomorphological region, is a perfect location to unravel the geologic nature of seismic hazards. The Chilean segment of the Nazca-South American subduction zone has experienced mega-earthquakes with Moment Magnitudes (Mw) >8.5 (e.g., Mw 9.5 Valdivia, 1960; Mw 8.8 Maule, 2010) and many large earthquakes with Mw >7.5, both with recurrence times of tens to hundreds of years. By contrast, crustal faults within the overriding South American plate commonly have longer recurrence times (thousands of years) and are known to produce earthquakes with maximum Mw of 7.0 to 7.5. Subduction-type earthquakes are considered the principal seismic hazard in Chile, with the potential to cause significant damage to its population and economy. However crustal (non-subduction) earthquakes can also cause great destruction at a local scale, because of their shallower hypocentral depth. Nevertheless, the nature, timing and slip rates of crustal seismic sources in the Chilean Andes remain poorly constrained. This work aims to address the seismic potential of the crustal faults in Chile, contributing to the estimation of key fault parameters for the seismic hazard assessment. We have examined the main parameters involved in the magnitude of an earthquake, including length, width and mean displacement of some case studies crustal faults and their morphotectonic settings, exposing the parametrical similarities in longitudinal domains (N-S stripes) and disparity from W to E, across latitudinal domains. The maximum hypocentral depths for crustal earthquakes vary across margin parallel tectonic domains aligned parallel, from 25-30 km in the outer forearc to 8-12 km in the volcanic arc, thus allowing for a first-order approach for seismic potential assessment. Current structural, paleoseismological and geodetic data, although sparse and limited, suggest that slip rates of Chilean crustal faults range from 0.2 mm/yr (in the forearc region) to up to 7.0 mm/yr (in the intra-arc region). The different tectonic modes for crustal fault reactivation and their wide range of slip rates complicates the estimation of seismic hazard. A rigorous seismic hazard assessment must therefore consider the different tectonic settings, timing and slip rates of Andean crustal faults. Understanding the nature of these faults will allow a better evaluation of the associated seismic hazard, and better constraints to be placed on their relationship with the subduction seismic cycle.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.46 n.1 20192019-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062019000100032en10.5027/andgeov46n1-3067
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Crustal Faults Seismic Hazard Neotectonics Crustal earthquakes Paleoseismology Chilean Andes
spellingShingle	Crustal Faults Seismic Hazard Neotectonics Crustal earthquakes Paleoseismology Chilean Andes Santibáñez,Isabel Cembrano,José García-Pérez,Tiaren Costa,Carlos Yáñez,Gonzalo Marquardt,Carlos Arancibia,Gloria González,Gabriel Crustal faults in the Chilean Andes: geological constraints and seismic potential
description	ABSTRACT The Chilean Andes, as a characteristic tectonic and geomorphological region, is a perfect location to unravel the geologic nature of seismic hazards. The Chilean segment of the Nazca-South American subduction zone has experienced mega-earthquakes with Moment Magnitudes (Mw) >8.5 (e.g., Mw 9.5 Valdivia, 1960; Mw 8.8 Maule, 2010) and many large earthquakes with Mw >7.5, both with recurrence times of tens to hundreds of years. By contrast, crustal faults within the overriding South American plate commonly have longer recurrence times (thousands of years) and are known to produce earthquakes with maximum Mw of 7.0 to 7.5. Subduction-type earthquakes are considered the principal seismic hazard in Chile, with the potential to cause significant damage to its population and economy. However crustal (non-subduction) earthquakes can also cause great destruction at a local scale, because of their shallower hypocentral depth. Nevertheless, the nature, timing and slip rates of crustal seismic sources in the Chilean Andes remain poorly constrained. This work aims to address the seismic potential of the crustal faults in Chile, contributing to the estimation of key fault parameters for the seismic hazard assessment. We have examined the main parameters involved in the magnitude of an earthquake, including length, width and mean displacement of some case studies crustal faults and their morphotectonic settings, exposing the parametrical similarities in longitudinal domains (N-S stripes) and disparity from W to E, across latitudinal domains. The maximum hypocentral depths for crustal earthquakes vary across margin parallel tectonic domains aligned parallel, from 25-30 km in the outer forearc to 8-12 km in the volcanic arc, thus allowing for a first-order approach for seismic potential assessment. Current structural, paleoseismological and geodetic data, although sparse and limited, suggest that slip rates of Chilean crustal faults range from 0.2 mm/yr (in the forearc region) to up to 7.0 mm/yr (in the intra-arc region). The different tectonic modes for crustal fault reactivation and their wide range of slip rates complicates the estimation of seismic hazard. A rigorous seismic hazard assessment must therefore consider the different tectonic settings, timing and slip rates of Andean crustal faults. Understanding the nature of these faults will allow a better evaluation of the associated seismic hazard, and better constraints to be placed on their relationship with the subduction seismic cycle.
author	Santibáñez,Isabel Cembrano,José García-Pérez,Tiaren Costa,Carlos Yáñez,Gonzalo Marquardt,Carlos Arancibia,Gloria González,Gabriel
author_facet	Santibáñez,Isabel Cembrano,José García-Pérez,Tiaren Costa,Carlos Yáñez,Gonzalo Marquardt,Carlos Arancibia,Gloria González,Gabriel
author_sort	Santibáñez,Isabel
title	Crustal faults in the Chilean Andes: geological constraints and seismic potential
title_short	Crustal faults in the Chilean Andes: geological constraints and seismic potential
title_full	Crustal faults in the Chilean Andes: geological constraints and seismic potential
title_fullStr	Crustal faults in the Chilean Andes: geological constraints and seismic potential
title_full_unstemmed	Crustal faults in the Chilean Andes: geological constraints and seismic potential
title_sort	crustal faults in the chilean andes: geological constraints and seismic potential
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2019
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062019000100032
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Crustal faults in the Chilean Andes: geological constraints and seismic potential

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