Implications for Shallow Magma Transfer During the 2017 and 2018 Eruptions at Fernandina (Galápagos) Inferred From InSAR Data

Abstract

Basaltic shields with summit calderas are among the most active volcanoes on Earth, experiencing repeated eruptions over decades (

Complex paths of magma propagation at Fernandina (Galápagos): The coexistence of circumferential and radial dike intrusion during the January 2020 eruption

“…To reduce the number of variables, I held xed the depth of the deep and the shallow reservoir at 5000 and 1080 m below the surface respectively, according to previous studies (Bagnardi & Amelung, 2012; Chadwick et al, 2011). The combination of sources used for modelling the observed deformations has been obtained through a trial-and-error approach, in which I started by testing a combination of sources similar to that used for modelling previous deformations at Fernandina (Bagnardi et al, 2013;Chadwick et al, 2011;Galetto et al, 2023b) and then, if these sources did not provide satisfying solutions (unrealistic or with large residuals), I modi ed them to obtain a combination of sources that were realistic and signi cantly reduced the residuals.…”

“…From 2017 to 2020, three closes in time eruptions occurred at Fernandina: a circumferential eruption near the SW caldera rim in September 2017, a radial eruption on the north ank in June 2018 and a circumferential eruption near the E caldera rim in January 2020 (Fig. 1b; Bernard et al, 2022;Vasconez et al, 2022;Galetto et al, 2023b). This latter eruption, characterized by lava ow emission, started on January 12 and ended the day after (Bernard et al, 2022).…”

“…Volcanic activity in these volcanoes is often associated with complex paths of magma propagation, sometimes also with intrusions in multiple directions that can potentially trigger eruptions in different location of the volcano. Complex paths of magma propagation have characterized for example some recent eruptions at Ambrym (Vanuatu), Piton de la Fournaise (Réunion Island), Etna (Italy), Bárðarbunga and Eyjafjallajökull (Iceland) and the wester Galápagos volcanoes (Acocella & Neri, 2003;Bagnardi et al, 2013;Sigmundsson et al, 2010Sigmundsson et al, , 2015Shreve et al, 2021;Dumont et al, 2022;Galetto et al, 2023b). It is therefore important to investigate how magma accumulates and propagates in basaltic shields before and during each eruption, to increase our knowledge on these processes and to better forecast how magma might propagate in future eruptions.…”

“…However, recent studies show that eruptions at western Galápagos can be characterized by further complexities like intrusions in multiple directions (e.g. the 2008 eruption at Cerro Azul and the 2018 eruption at Fernandina; Galetto et al, 2020; 2023b), sill-like intrusions that trigger radial eruptions (2018 eruption at Sierra Negra; Davis et al, 2021) and radial dikes that bifurcated outside the caldera area (2018 eruption at Fernandina; Galetto et al,2023b). In this study, I investigate with Interferometric Synthetic Aperture Radar data (InSAR) data and geodetic modelling the pre-and syn-eruptive deformation of the January 2020 circumferential eruption occurred at Fernandina volcano (Galápagos).…”

“…In this study, I investigate with Interferometric Synthetic Aperture Radar data (InSAR) data and geodetic modelling the pre-and syn-eruptive deformation of the January 2020 circumferential eruption occurred at Fernandina volcano (Galápagos). I limited the analysis of the pre-eruptive period to the time span from January 2019 to January 2020, since deformations occurred before this time have already been analysed by Galetto et al, (2023b). Results show a pre-eruptive in ow of new magma in the magma reservoirs of Fernandina.…”