Deformations and Morphology Changes Associated with the 2016–2017 Eruption Sequence at Bezymianny Volcano, Kamchatka

Abstract

Lava domes grow by extrusions and intrusions of viscous magma often initiating froma central volcanic vent, and they are frequently defining the source region of hazardous explosiveeruptions and pyroclastic density currents. Thus, close monitoring of dome building processesis crucial, but often limited to low data resolution, hazardous access, and poor visibility. Here,we investigated the 2016–2017 eruptive sequence of the dome building Bezymianny volcano,Kamchatka, with spot-mode TerraSAR-X acquisitions, and complement the analysis with webcamimagery and seismic data. Our results reveal clear morphometric changes preceding eruptions that areassociated with intrusions and extrusions. Pixel offset measurements show>7 months of precursoryplug extrusion, being locally defined and exceeding 30 m of deformation, chiefly without detectedseismicity. After a short explosion, three months of lava dome evolution were characterised byextrusions and intrusion. Our data suggest that the growth mechanisms were significantly governedby magma supply rate and shallow upper conduit solidification that deflected magmatic intrusionsinto the uppermost parts of the dome. The integrated approach contributes significantly to a betterunderstanding of precursory activity and complex growth interactions at dome building volcanoes,and shows that intrusive and extrusive growth is acting in chorus at Bezymianny volcano.