Ring Fault Slip Reversal at Baroarbunga Volcano, Iceland: Seismicity During Caldera Collapse and Re-Inflation 2014-2018

Microearthquakes reveal the kinematics of the Baroarbunga caldera ring fault; during the 2014-2015 rifting event and gradual caldera collapse, and its subsequent, ongoing re-inflation. Tightly constrained focal mechanisms during re-inflation have reversed phase arrival polarities from events during the caldera collapse. Thus, the inner side of the steeply dipping northern caldera faults (averaging 81 +/- 8 degrees) has been moving upwards during the post-eruptive period. Both precise relative relocations of the seismicity and fault plane solutions confirm that this is due to slip reversal on the same ring fault structure.

Automated summary

Microearthquakes provide insight into the movement of the Baroarbunga caldera ring fault, including the 2014-2015 rifting event, gradual caldera collapse, and ongoing re-inflation. The research indicates that during the post-eruptive period, the inner side of the steeply dipping northern caldera faults has been moving upwards due to slip reversal on the same ring fault structure.