From prodigious volcanic degassing to caldera subsidence and quiescence at Ambrym (Vanuatu): the influence of regional tectonics

Abstract : Eruptive activity shapes volcanic edifices. The formation of broad caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts a 12-km wide caldera and several intensely-degassing lava lakes confined to intra-caldera cones. Using satellite remote sensing of deformation, gas emissions and thermal anomalies, combined with seismicity and ground observations, we show that in December 2018 an intra-caldera eruption at Ambrym preceded normal faulting with >2 m of associated uplift along the eastern rift zone and 2.5 m of caldera-wide subsidence. Deformation was caused by lateral migration of >0.4 cubic kilometers of magma into the rift zone, extinguishing the lava lakes, and feeding a submarine eruption in the rift edge. Recurring rifting episodes, favored by stress induced by the D'Entrecasteaux Ridge collision against the New Hebrides arc, lead to progressive subsidence of Ambrym's caldera and concurrent draining of the lava lakes. Although counterintuitive, convergent margin systems can induce rift zone volcanism and subsequent caldera subsidence.
Complete list of metadatas

Cited literature [75 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-02399004
Contributor : Raphael Grandin <>
Submitted on : Wednesday, December 11, 2019 - 3:51:36 PM
Last modification on : Wednesday, January 8, 2020 - 1:08:00 AM

File

Shreve_2019_Ambrym_eruption_De...
Publisher files allowed on an open archive

Identifiers

Citation

Tara Shreve, Raphael Grandin, Marie Boichu, Esline Garaebiti, Yves Moussallam, et al.. From prodigious volcanic degassing to caldera subsidence and quiescence at Ambrym (Vanuatu): the influence of regional tectonics. Scientific Reports, Nature Publishing Group, 2019, 9, pp.18868. ⟨10.1038/s41598-019-55141-7⟩. ⟨hal-02399004v2⟩

Share

Metrics

Record views

51

Files downloads

60