Shuang Yi (1), Nico Sneeuw (1), James Foster (1), Yuanjin Pan (2)

1) Institute of Geodesy, University of Stuttgart, Stuttgart, Germany

2) School of Geodesy and Geomatics, Wuhan University, Wuhan, China

Groundwater has recently been hypothesized to have triggered the 2018 Hawaiian volcanic eruption, but the causality is controversial. Here, using observations of spaceborne gravimetry and ground deformation, we show that magma accumulation beneath Hawai’i appears to be modulated by significant groundwater changes. We find that a severe drought of -9.9 km3 occurred from 2009 to 2014, coupled with vanished ground swelling in Mauna Loa Caldera and extensive rebound deformation; rapid groundwater recovery from 2015 to 2017 was accompanied by resumed inflation in Mauna Loa and Kilauea calderas. Strain analyses indicate that the drought promoted contraction of magmatic pathways below 20 km and the recovery facilitated magma upwelling. Enhanced magma accumulation since 2015 ultimately led to the 2018 Kilauea eruption. This study reveals detailed correlations between groundwater changes and magmatic activities in Hawai’i and contributes to the understanding of magma dynamics on decadal timescales.