Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise

In subduction zones, elevated pore fluid pressure, generally linked to metamorphic dehydration reactions, has a profound influence on the mechanical behavior of the plate interface and forearc crust through its control on effective stress. We use seismic noise–based monitoring to characterize seismi...

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Main Authors: Chaves, Esteban, Schwartz, Susan
Format: Artículo
Language: Inglés
Published: American Association for the Advancement of Sciences (AAAS) 2024
Subjects:
Online Access: http://hdl.handle.net/11056/27608
id RepoUNACR27608
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spelling RepoUNACR276082024-04-10T18:28:30Z Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise Chaves, Esteban Schwartz, Susan PENÍNSULA DE NICOYA (COSTA RICA) NICOYA PENINSULA (COSTA RICA) TERREMOTOS EARTHQUAKES SISMOLOGÍA SEISMOLOGY ONDAS SÍSMICAS SEISMIC WAVES In subduction zones, elevated pore fluid pressure, generally linked to metamorphic dehydration reactions, has a profound influence on the mechanical behavior of the plate interface and forearc crust through its control on effective stress. We use seismic noise–based monitoring to characterize seismic velocity variations following the 2012 Nicoya Peninsula, Costa Rica earthquake [Mw (moment magnitude) 7.6] that we attribute to the presence of pressurized pore fluids. Our study reveals a strong velocity reduction (~0.6%) in a region where previous work identified high forearc pore fluid pressure. The depth of this velocity reduction is constrained to be below 5 km and therefore not the result of near-surface damage due to strong ground motions; rather, we posit that it is caused by fracturing of the fluid-pressurized weakened crust due to dynamic stresses. Although pressurized fluids have been implicated in causing coseismic velocity reductions beneath the Japanese volcanic arc, this is the first report of a similar phenomenon in a subduction zone setting. It demonstrates the potential to identify pressurized fluids in subduction zones using temporal variations of seismic velocity inferred from ambient seismic noise correlations. En las zonas de subducción, la elevada presión de los fluidos de poro, generalmente vinculada a reacciones de deshidratación metamórfica, tiene una profunda influencia en el comportamiento mecánico de la interfaz de la placa y la corteza de antepaís a través de su control sobre la tensión efectiva. Utilizamos la monitorización basada en el ruido sísmico para caracterizar las variaciones de velocidad sísmica tras el terremoto de 2012 en la Península de Nicoya, Costa Rica [Mw (magnitud de momento) 7,6] que atribuimos a la presencia de fluidos de poro presurizados. Nuestro estudio revela una fuerte reducción de la velocidad (~0,6%) en una región en la que trabajos previos identificaron una alta presión de fluidos de poro en el antepaís. La profundidad de esta reducción de la velocidad está limitada a menos de 5 km y, por lo tanto, no es el resultado de daños cerca de la superficie debidos a fuertes movimientos del terreno; más bien, postulamos que está causada por la fractura de la corteza debilitada por fluidos presurizados debido a tensiones dinámicas. Aunque los fluidos presurizados han estado implicados en la reducción de la velocidad sísmica bajo el arco volcánico japonés, éste es el primer informe de un fenómeno similar en una zona de subducción. Demuestra el potencial para identificar fluidos presurizados en zonas de subducción utilizando variaciones temporales de la velocidad sísmica inferidas a partir de correlaciones de ruido sísmico ambiental. Universidad Nacional, Costa Rica Universidad de California, Santa Cruz Observatorio Vulcanológico y Sismológico de Costa Rica 2024-04-10T18:23:43Z 2024-04-10T18:23:43Z 2016 http://purl.org/coar/resource_type/c_6501 23752548 http://hdl.handle.net/11056/27608 10.1126/sciadv.1501289 eng Acceso abierto Atribución-No Comercial 4.0 Internacional http://creativecommons.org/licenses/by-nc/4.0/ application/pdf American Association for the Advancement of Sciences (AAAS) Science Advance vol.2 no.1 1-6 2016
institution Universidad Nacional de Costa Rica
collection Repositorio UNA-Costa Rica
language Inglés
topic PENÍNSULA DE NICOYA (COSTA RICA)
NICOYA PENINSULA (COSTA RICA)
TERREMOTOS
EARTHQUAKES
SISMOLOGÍA
SEISMOLOGY
ONDAS SÍSMICAS
SEISMIC WAVES
spellingShingle PENÍNSULA DE NICOYA (COSTA RICA)
NICOYA PENINSULA (COSTA RICA)
TERREMOTOS
EARTHQUAKES
SISMOLOGÍA
SEISMOLOGY
ONDAS SÍSMICAS
SEISMIC WAVES
Chaves, Esteban
Schwartz, Susan
Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
description In subduction zones, elevated pore fluid pressure, generally linked to metamorphic dehydration reactions, has a profound influence on the mechanical behavior of the plate interface and forearc crust through its control on effective stress. We use seismic noise–based monitoring to characterize seismic velocity variations following the 2012 Nicoya Peninsula, Costa Rica earthquake [Mw (moment magnitude) 7.6] that we attribute to the presence of pressurized pore fluids. Our study reveals a strong velocity reduction (~0.6%) in a region where previous work identified high forearc pore fluid pressure. The depth of this velocity reduction is constrained to be below 5 km and therefore not the result of near-surface damage due to strong ground motions; rather, we posit that it is caused by fracturing of the fluid-pressurized weakened crust due to dynamic stresses. Although pressurized fluids have been implicated in causing coseismic velocity reductions beneath the Japanese volcanic arc, this is the first report of a similar phenomenon in a subduction zone setting. It demonstrates the potential to identify pressurized fluids in subduction zones using temporal variations of seismic velocity inferred from ambient seismic noise correlations.
format Artículo
author Chaves, Esteban
Schwartz, Susan
author_sort Chaves, Esteban
title Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
title_short Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
title_full Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
title_fullStr Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
title_full_unstemmed Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
title_sort monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise
publisher American Association for the Advancement of Sciences (AAAS)
publishDate 2024
url http://hdl.handle.net/11056/27608
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score 12.24763