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Earthquake-induced fault reactivation at oblique subduction zones: from cause to effect

Applicant Lupi Matteo
Number 154815
Funding scheme Ambizione
Research institution Section des Sciences de la Terre et de l'environnement Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geology
Start/End 01.02.2015 - 31.08.2016
Approved amount 174'355.00
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All Disciplines (2)

Discipline
Geology
Geophysics

Keywords (3)

Fault reactivation; volcanic arc; earthquake

Lay Summary (Italian)

Lead
Interazione tra sistemi geologici e grandi terremoti
Lay summary
Lo scopo principale di questo studio è quello di indagare come i grandi sovrascorrimenti che si verificano presso i
margini di placca convergenti siano in grado di riattivare faglie trascorrenti nella placca superiore.
I soggetti di questo studio saranno i sistemi vulcanici ed idrotermali, spesso caratterizzari da condizioni critiche in profondita', che si sono sviluppati in corrispondenza di zone di trasporto laterale nell'arco vulcanico.

L'ipotesi che viene qui proposta suggerisce che l'azione combinata degli stress statici e dinamici possa riattivare tali strutture promuovendo la risalita di fluidi residenti a livelli strutturali profondi.

In particolare, questo studio cerchera' di rispondere alle seguenti tre domande:
1) Che tipo di deformazione tettonica si instaura nell'arco vulcanico dopo un grande sovrascorrimento?
2) Come i sistemi in condizioni critiche rispondono all'energia sismica che li attraversa?
3) Quali sono le tempistiche durante le quali i magmi ed i fluidi in generale possono migrare attraverso piani di faglia riattivati?

Questo studio prendera' in considerazione 1) la regione del Maule, Chile, 2) l' eruzione di fango denominata LUSI in Java, ed 3) il vulcano Sinabung, Sumatra. Nello specifico questo studio si prefigge di:
- Analizzare i dati sismici che sono stati registrati in Chile dal 2013 al 2015 nell'arco vulcanico.
- Installare una rete sismica intorno al all'eruzione di fango LUSI in Java.
- Investigare gli effetti del Grande terremoto di Sumatra del 2004 sulla Great Sumatran Fault
- Combinare i dati ottenutio nel corso dello studio per sviluppare modelli geofisici di interazione tra terremoti e sistemi geologici.
Direct link to Lay Summary Last update: 20.01.2015

Responsible applicant and co-applicants

Employees

Collaboration

Group / person Country
Types of collaboration
Dr. Adriano Mazzini, Physics of Geological Processes, University of Oslo Norway (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Prof. Oliver Bachmann, Institute of Geochemistry and Petrology, ETH Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Abstract

The purpose of this study is to investigate how large-magnitude earthquakes occurring at oblique convergent margins reactivate strike slip faults in the overriding plate. More specifically, I suggest to focus on volcanic and hydrothermal systems developed upon strike slip fault zones characterised by near-critical conditions at depth. The hypothesis presented here suggests that the combined action of static and dynamic stresses imposed by the earthquake main-slip and after-slips alters the already near-lithostatic conditions at depth of the system promoting permeability enhancements, unclamping of locked faults and upwelling of deep-seated fluids. These processes mutually reinforce each other and may ultimately lead to volcanic and mud eruptions. The project aims to address three distinct and yet related questions: 1) What type of long-term tectonic deformation takes place in the volcanic arc after a large-magnitude earthquake? 2) How geological systems in near-critical conditions respond to incoming seismic waves? 3) How rapidly magmas migrate through unlocked fault planes? I propose to use data from three natural laboratories (the Maule region, Chile; the LUSI mud eruption, East Java; the Sinabung volcano, Sumatra) to investigate the post-seismic deformation of perturbed volcanic arcs and the sensitivity of hydrothermal and volcanic systems to incoming seismic energy. More specifically, this proposal asks for support to- Analyse seismic data currently being recorded in Chile; - Deploy a seismic array around the Watukosek fault (from Arjuno-Welirang volcano to the ongoing Lusi mud eruption), Java, and analyse the response of the Watukosesk fault system to seismic activity occurring at the Sunda subduction zone;- Investigate the effects of the M9.1 Andaman and the M8.6 Nias earthquakes on the Great Sumatran Fault that lead to the reactivation of the Sinabung volcano that was quiescent forthe last 500 years; - Combine geophysical, geological and stratigraphic datasets acquired throughout the study to constrain earthquake-fault interactions.The proposed study is divided in three distinct sections: first will investigate static stress triggering using the seismic network deployed in Chile from 35.5ºS to 37.3ºS. This will highlight the short-lived deformation in the region of the volcanic arc that faces the area affected by the maximum slip of the M8.8 2012 Maule earthquake. The second part will address dynamic stress triggering and the effects that incoming seismic energy has on critically stressed geological systems sitting upon strike slip faults, namely the on-going LUSI mud eruption, East Java. The third section of the project will quantify how static and dynamic stresses generated by the M8.6 Nias earthquakes (and possibly the M9.2 Andaman earthquake) may have unlocked the Great Sumatran Fault and initiated a vertical magma flow that lead to the reactivation the Sinabung volcano, Sumatra, after 500 years of quiescence. The study will benefit from the collaboration with ETH and international scientists working on complementary aspects of the same subject.
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