Analýza vulkanického tremoru během erupce sopky Fagradalsfjall, 2021

Sova, František

Volcanic tremors are low frequency seismic events, occurring prior to or during eruptions and are believed to be caused by the movement of magma. The study of those events can reveal subsurface processes during volcanic activity, furthermore it can help to reconstruct eruptions, which cannot be observed directly. The presented study describes the volcanic tremor during the 2021 Fagradals- fjall eruption in Iceland. Seismic data from several stations were processed to produce a half-year record of volcanic activity. Additionally, the tremor ampli- tude attenuation was investigated. The seismic record was marked by a reoccurring tremor signal in the fre- quency band 1-10 Hz, which temporally matched with the different phases of effusive eruption. Its amplitudes varied in time, showing three distinct pat- terns. The weak continuous tremor in the first weeks of eruption transitioned into regular pulses, lasting several minutes, and later into a different pulsation with a 1.5-day period. Those variations might reflect the changes in geometry and magma flow of the underground magmatic system. 1

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