Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients

Satellite gravimetry has proven to be a useful tool to identify mass anomalies along a subduction interface, interpreted as heterogeneities related to the rupture process during megathrust earthquakes. In the last years, different works, reinforced with data derived from satellite gravity missions a...

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Autor principal:	Folguera, Andrés
Publicado:	2017
Materias:	GOCE Megathrust earthquakes South central Andes Spherical harmonics Vertical gravity gradient Geodetic satellites Geophysics Harmonic analysis Satellites Seismology Tectonics Central Andes Gravity gradients Earthquakes earthquake magnitude earthquake rupture GRACE gravity field mapping satellite data satellite mission Andes
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00334553_v174_n1_p47_Alvarez http://hdl.handle.net/20.500.12110/paper_00334553_v174_n1_p47_Alvarez
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_00334553_v174_n1_p47_Alvarez
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spelling	paper:paper_00334553_v174_n1_p47_Alvarez2023-06-08T15:00:33Z Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients Folguera, Andrés GOCE Megathrust earthquakes South central Andes Spherical harmonics Vertical gravity gradient Geodetic satellites Geophysics Harmonic analysis Satellites Seismology Tectonics Central Andes GOCE Gravity gradients Megathrust earthquakes Spherical harmonics Earthquakes earthquake magnitude earthquake rupture GOCE GRACE gravity field mapping satellite data satellite mission Andes Satellite gravimetry has proven to be a useful tool to identify mass anomalies along a subduction interface, interpreted as heterogeneities related to the rupture process during megathrust earthquakes. In the last years, different works, reinforced with data derived from satellite gravity missions as GRACE and now GOCE, have analyzed not only the static component of the Earth gravity field, but also its temporal variations and relation to the seismic cycle. In particular, during the last decade, the Chilean margin has been affected by three megathrust earthquakes (with Mw >8): Maule 2010 Mw = 8.8, Pisagua 2014 Mw = 8.2 and recently the Mw = 8.3 Illapel event. Then, the recently completed GOCE mission (November 2009 to November 2013) offered a unique opportunity to study the Maule February 2010 and Pisagua April 2014 events by means of gravity gradients, directly measured at satellite height altitudes, which allowed mapping density heterogeneities with greater detail than the gravity anomaly which has been used in most studies up to now. In the present work, we use the last GOCE model (GO_CONS_GCF_2_DIR_R5), the one of higher spatial resolution (N = 300, λ/2 ≈ 66 km) derived from satellite-only data. The methodology used is the same as that to study the previous events, with the addition that now we derived a relation between the associated depths of a causative mass with a determined degree of the spherical harmonic expansion. This allowed to “decompose” the gravimetric signal, by cutting off the degree/order of the harmonic expansion, as depth increases. From this analysis, we found that prominent oceanic features such as the Challenger fracture zone and the Juan Fernandez ridge played a key role in latitudinal seismic segmentation for the Illapel earthquake rupture zone, acting as barriers/attenuators to the seismic energy release. We compared the slip model from Tilmann et al. (Geophysical Research Letters 43: 574–583. doi:10.1002/2015GL066963, 2016) for the Illapel earthquake with vertical gravity gradient with and without sediment correction, and at different degree/order of the harmonic expansion. From this analysis, we inferred that prominent oceanic features over the subducting Nazca plate play a key role in seismic segmentation not only at heavily sedimented trenches, but also at sediment-starved segments. © 2016, Springer International Publishing. Fil:Folguera, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2017 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00334553_v174_n1_p47_Alvarez http://hdl.handle.net/20.500.12110/paper_00334553_v174_n1_p47_Alvarez
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	GOCE Megathrust earthquakes South central Andes Spherical harmonics Vertical gravity gradient Geodetic satellites Geophysics Harmonic analysis Satellites Seismology Tectonics Central Andes GOCE Gravity gradients Megathrust earthquakes Spherical harmonics Earthquakes earthquake magnitude earthquake rupture GOCE GRACE gravity field mapping satellite data satellite mission Andes
spellingShingle	GOCE Megathrust earthquakes South central Andes Spherical harmonics Vertical gravity gradient Geodetic satellites Geophysics Harmonic analysis Satellites Seismology Tectonics Central Andes GOCE Gravity gradients Megathrust earthquakes Spherical harmonics Earthquakes earthquake magnitude earthquake rupture GOCE GRACE gravity field mapping satellite data satellite mission Andes Folguera, Andrés Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients
topic_facet	GOCE Megathrust earthquakes South central Andes Spherical harmonics Vertical gravity gradient Geodetic satellites Geophysics Harmonic analysis Satellites Seismology Tectonics Central Andes GOCE Gravity gradients Megathrust earthquakes Spherical harmonics Earthquakes earthquake magnitude earthquake rupture GOCE GRACE gravity field mapping satellite data satellite mission Andes
description	Satellite gravimetry has proven to be a useful tool to identify mass anomalies along a subduction interface, interpreted as heterogeneities related to the rupture process during megathrust earthquakes. In the last years, different works, reinforced with data derived from satellite gravity missions as GRACE and now GOCE, have analyzed not only the static component of the Earth gravity field, but also its temporal variations and relation to the seismic cycle. In particular, during the last decade, the Chilean margin has been affected by three megathrust earthquakes (with Mw >8): Maule 2010 Mw = 8.8, Pisagua 2014 Mw = 8.2 and recently the Mw = 8.3 Illapel event. Then, the recently completed GOCE mission (November 2009 to November 2013) offered a unique opportunity to study the Maule February 2010 and Pisagua April 2014 events by means of gravity gradients, directly measured at satellite height altitudes, which allowed mapping density heterogeneities with greater detail than the gravity anomaly which has been used in most studies up to now. In the present work, we use the last GOCE model (GO_CONS_GCF_2_DIR_R5), the one of higher spatial resolution (N = 300, λ/2 ≈ 66 km) derived from satellite-only data. The methodology used is the same as that to study the previous events, with the addition that now we derived a relation between the associated depths of a causative mass with a determined degree of the spherical harmonic expansion. This allowed to “decompose” the gravimetric signal, by cutting off the degree/order of the harmonic expansion, as depth increases. From this analysis, we found that prominent oceanic features such as the Challenger fracture zone and the Juan Fernandez ridge played a key role in latitudinal seismic segmentation for the Illapel earthquake rupture zone, acting as barriers/attenuators to the seismic energy release. We compared the slip model from Tilmann et al. (Geophysical Research Letters 43: 574–583. doi:10.1002/2015GL066963, 2016) for the Illapel earthquake with vertical gravity gradient with and without sediment correction, and at different degree/order of the harmonic expansion. From this analysis, we inferred that prominent oceanic features over the subducting Nazca plate play a key role in seismic segmentation not only at heavily sedimented trenches, but also at sediment-starved segments. © 2016, Springer International Publishing.
author	Folguera, Andrés
author_facet	Folguera, Andrés
author_sort	Folguera, Andrés
title	Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients
title_short	Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients
title_full	Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients
title_fullStr	Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients
title_full_unstemmed	Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients
title_sort	analysis of the illapel mw = 8.3 thrust earthquake rupture zone using goce-derived gradients
publishDate	2017
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00334553_v174_n1_p47_Alvarez http://hdl.handle.net/20.500.12110/paper_00334553_v174_n1_p47_Alvarez
work_keys_str_mv	AT folgueraandres analysisoftheillapelmw83thrustearthquakerupturezoneusinggocederivedgradients
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Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients

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