Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Gal\xe1pagos Islands

Andrew F Bell,Cynthia Ebinger,Nathan J Meier,Benjamin Bernard,Sarah-Jaye Oliva,Céline Liorzou,Mario Ruiz,Andres Gorki Ruiz,Matthew Gleeson,Marco Bagnardi,Michael J Stock,Peter C La Femina,James Grannell,Christopher J Bean,Stephen Hernandez,Martin Möllhoff,Paul Lundgren,Machel Higgins,Falk Amelung

doi:10.1038/s41467-021-21596-4

Abstract

Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity of observations has obscured the mechanisms underpinning such behaviour. Here we combine a unique multiparametric dataset to show how the 2018 eruption of Sierra Negra contributed to caldera resurgence. Magma supply to a shallow reservoir drove 6.5 m of pre-eruptive uplift and seismicity over thirteen years, including an Mw5.4 earthquake that triggered the eruption. Although co-eruptive magma withdrawal resulted in 8.5 m of subsidence, net uplift of the inner-caldera on a trapdoor fault resulted in 1.5 m of permanent resurgence. These observations reveal the importance of intra-caldera faulting in affecting resurgence, and the mechanisms of eruption in the absence of well-developed rift systems.

Highlights

Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence
The multiparametric observations of the 2018 eruption of Sierra Negra contrast markedly with those associated with the eruptions at Kilauea in 2018 and Bárðarbunga in 2014: (1) The eruption at Sierra Negra was preceded by large amplitude, prolonged, and multi-staged uplift and intense accompanying seismicity
Trapdoor faulting resulted in residual intra-caldera resurgence of 1.5 m

Summary

Introduction

Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. Some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity These systems display long-term intra-caldera uplift, or resurgence. The steep upper flanks, large calderas[8,12,13], and circumferential and radial eruptive fissures[14,15] of the volcanoes of the western Galápagos Islands distinguish them from more intensively studied basaltic systems in Hawaii and Iceland. This distinction has been furthered by observations from satellite data of prolonged surface uplift and trapdoor faulting[6,16]. By the end of the eruption on 23 August 2018, lava flows covered an area of 30.6 km[2] (ref. 28)

Methods

Results

Conclusion