Abstract:

In 2021, the eruption in Geldingadalir valley exhibited a very variable eruptive behavior. The initially continous eruption transitioned to minute-long episodes in early May and, by mid-July, changed to hour-long episodes. Before the transition, on 2 July 2021, the lava pond in the crater drained completely for the first time. Approximately an hour later, several dark plumes with different intensities emerged from the crater and parts of the crater wall collapsed into the crater. These observations were accompanied by small seismic and acoustic signals. We analyse these signals jointly with webcam footage and orthophotos. We test different source models to explain the seismic signals through probabilistic source inversion. We also speculate on the role of these crater shape-changing events on the eruptive behaviour.

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