Comment to Shreve and Delgado (2023)—“Trapdoor Fault Activation: A Step Toward Caldera Collapse at Sierra Negra, Galapagos, Ecuador”

In their article entitled “Trapdoor Fault Activation: A Step Toward Caldera Collapse at Sierra Negra, Galapagos, Ecuador” Shreve and Delgado (2023, https://doi.org/10.1029/2023jb026437) examine co-eruptive deformation during the 2018 eruption of Sierra Negra Volcano. One of their major conclusions is that the 2018 eruption, and specifically co-eruptive faulting, represents the initial stages of caldera collapse. They reach this conclusion because they focus their analysis solely on co-eruptive deformation, and do not investigate the total (net) deformation for the 2005 to 2018 eruption cycle. Bell, La Famina, et al. (2021, https://doi.org/10.1038/s41467-021-21596-4) investigated both the pre- and co-eruptive phases of the 2018 eruption and showed that net deformation was one of caldera resurgence, not subsidence. In this comment, we demonstrate that the conclusion of collapse, or even initiation of collapse, is attributable to not accounting for pre-eruptive deformation on the intra-caldera Trapdoor Fault system and incorrectly assuming that the volcano-tectonic dynamics of Sierra Negra mimic those of other basaltic calderas.