Fig. 4: Mechanism of correlated displacements in the Western Galápagos.

a Cumulative intrusive volume in the Western Galápagos from 2000 to 2022 (modified from ref. ⁵⁶), with periods of correlated displacements annotated (this study, and modified from ref. ¹⁷). Each coloured area corresponds to a different volcanic system, while the coloured vertical bars denote the observed evidence of related displacement (e.g., during an eruption, or volcanic unrest)—eruptions that occurred, but did not result in observed related displacements are faintly marked. The grey area marks periods where there was a lack of enough satellite data to perform modelling (“Methods”). The embedded pie charts show the cumulative distribution of magma at each volcano, first for the period from 2000 to 2010 (modified from ref. ⁵⁶) and second for the from 2017 to 2022 (i.e., not including volumes from 2000 to 2010). Alcedo is not included as it subsided over this period, and neither are volumes lost during an eruption (e.g., those that were removed in Fig. 3). b Schematic diagram of a proposed mechanism of correlated uplift. Neighbouring volcanic systems are supplied from the same deeper source; periodic changes in magma supply from this source cause these volcanoes to uplift simultaneously. These systems may be hydraulically connected at some depth to facilitate correlated displacements during an eruption. c Schematic diagram of a proposed mechanism of correlated subsidence. As magma supply wanes, cooling and crystallisation dominate, decreasing reservoir volume and allowing neighbouring volcanic systems to deform simultaneously. d Schematic diagram of a proposed mechanism of negatively correlated unrest. One of these then erupts while the other continues to inflate, causing subsidence, while the neighbour continues to inflate. e Negatively correlated displacement due to a change in magma supply.