Abstract
Structure and dynamics of fault systems can be investigated using repeating earthquakes as repeatable seismic sources, alongside ground deformation measurements. Here we utilise a dataset of repeating earthquakes which occurred between 2000 and 2019 along the transtensive Pernicana fault system on the northeast flank of Mount Etna, Italy, to investigate the fault structure, as well as the triggering mechanisms of the seismicity. By grouping the repeating earthquakes into families and integrating the seismic data with GPS measurements of ground deformation, we identify four distinct portions of the fault. Each portion shows a different behaviour in terms of seismicity, repeating earthquakes and ground deformation, which we attribute to structural differences including a segmentation of the fault plane at depth. The recurrence intervals of repeating earthquake families display a low degree of regularity which suggests an episodic triggering mechanism, such as magma intrusion, rather than displacement under a constant stress.
Highlights
Structure and dynamics of fault systems can be investigated using repeating earthquakes as repeatable seismic sources, alongside ground deformation measurements
We calculated the coefficient of variation, defined as the standard deviation divided by the mean and showing the probabilistic behavior of a random variable, to quantify the variability within the repeating earthquake families[4]
Etna during 2000–2019 allowed us to identify an extraordinary wealth of families of repeating earthquakes generated by the PF, an ~E–Wtrending 18-km-long transtensive structure accommodating the seaward sliding of the volcano’s eastern flank
Summary
Structure and dynamics of fault systems can be investigated using repeating earthquakes as repeatable seismic sources, alongside ground deformation measurements. By grouping the repeating earthquakes into families and integrating the seismic data with GPS measurements of ground deformation, we identify four distinct portions of the fault. Each portion shows a different behaviour in terms of seismicity, repeating earthquakes and ground deformation, which we attribute to structural differences including a segmentation of the fault plane at depth. Repeating earthquakes can be triggered by repeated ruptures of a fault patch driven to failure by aseismic creep on the surrounding fault plane[4,5] They can be identified by constraining the source areas and/or analyzing the waveform characteristics[6]. It has been suggested that flank sliding can facilitate the passive rise of magma[33]
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