Title :

What Triggers Caldera Ring-Fault Subsidence at Ambrym Volcano? Insights From the 2015 Dike Intrusion and Eruption

Author(s) :

Shreve, T. [Auteur]
Carnegie Institution for Science
Institut de Physique du Globe de Paris [IPGP (UMR_7154)]
Grandin, R. [Auteur]
Institut de Physique du Globe de Paris [IPGP (UMR_7154)]
Smittarello, D. [Auteur]
Université Savoie Mont Blanc [USMB [Université de Savoie] [Université de Chambéry]]
Cayol, V. [Auteur]
Laboratoire Magmas et Volcans [LMV]
Pinel, V. [Auteur]
Université Savoie Mont Blanc [USMB [Université de Savoie] [Université de Chambéry]]
Boichu, Marie [Auteur]
Laboratoire d'Optique Atmosphérique (LOA) - UMR 8518
Morishita, Y. [Auteur]

Journal title :

Journal of Geophysical Research : Solid Earth

Abbreviated title :

J. Geophys. Res.-Solid Earth

Volume number :

126

Pages :

-

Publication date :

2021-07-21

ISSN :

2169-9313

English keyword(s) :

basaltic volcanism
calderas
rift zones
ring-faults
stress transfer

HAL domain(s) :

Planète et Univers [physics]/Océan, Atmosphère

English abstract : [en]

Surface deformation accompanying dike intrusions is dominated by uplift and horizontal motion directly related to the intrusions. In some cases, it includes subsidence due to associated magma reservoir deflation. When ...
Show more >Surface deformation accompanying dike intrusions is dominated by uplift and horizontal motion directly related to the intrusions. In some cases, it includes subsidence due to associated magma reservoir deflation. When reservoir deflation is large enough, it can form, or reactivate pre-existing, caldera ring-faults. Ring-fault reactivation, however, is rarely observed during moderate-sized eruptions. On February 21st, 2015 at Ambrym volcano in Vanuatu, a basaltic dike intrusion produced more than 1 meter of co-eruptive uplift, as measured by InSAR, SAR correlation, and Multiple Aperture Interferometry (MAI). Here we show that an average of ∼40 cm of slip occurred on a normal caldera ring-fault during this moderate-sized (VEI < 3) event, which intruded a volume of ∼24 million cubic meters and erupted ∼9.3 million cubic meters of lava (DRE). Using the 3D Mixed Boundary Element Method, we explore the stress change imposed by the opening dike and the depressurizing reservoir on a passive, frictionless fault. Normal fault slip is promoted when stress is transferred from a depressurizing reservoir beneath one of Ambrym’s main craters. After estimating magma compressibility, we provide an upper-bound on the critical fraction (f = 7%) of magma extracted from the reservoir to trigger fault slip. We infer that broad basaltic calderas may form in part by hundreds of subsidence episodes no greater than a few meters, as a result of magma extraction from the reservoir during moderate- sized dike intrusions.Show less >

Language :

Anglais

Audience :

Internationale

Popular science :

Non

Administrative institution(s) :

Université de Lille
CNRS

Collections :

• Laboratoire d'Optique Atmosphérique (LOA) - UMR 8518

Submission date :

2024-01-16T22:28:01Z
2024-02-08T12:44:55Z