S012-0020
Volcano monitoring and structural investigation with Distributed Acoustic Sensing at Mount Etna, Italy.
Volcano monitoring and structural investigation with Distributed Acoustic Sensing at Mount Etna, Italy.
Tuesday, 8 December 2020
Poster
Abstract:
Distributed Acoustic Sensing (DAS) technology has the ability to revolutionize volcanic processes monitoring and studies. Mount Etna is a complex volcanic structure where volcano-tectonic processes interact. We applied DAS to monitor and explore faults at several locations around Mount Etna volcano in 2018 and 2019.
Here, we focus on the analysis of strain rate records along a 1.3 km-long fibre optic cable deployed in Piano delle Concazze. This area is affected by several North-South trending faults and fractures, which accommodate extension of the nearby North-East Rift zone, where magmatic intrusions often occur. Segments of these faults and fractures are hidden by lava flows and volcano-clastic deposits produced by effusive and explosive Etna activity.
We identify and characterize volcano-related dynamic strain changes at an unprecedented high spatial (2 m) and temporal (1 kHz) sampling over a broad frequency range using DAS record analysis. The validation of the iDAS response is performed using dense network of conventional sensors (comprising 5 broadband seismometers, 15 short-period geophone and two arrays of 3 infrasound sensors) deployed along the fibre optic cable. We find excellent agreement, thus demonstrating for the first time the capability of DAS technology in sensing seismic waves generated by volcanic events.
The frequent and diverse Etna activity during the acquisition period (30 August - 16 September 2018) allowed us to record a wide variety of signals and, hence, to test the response of iDAS to several volcanic processes. We focus the analysis on the signals recorded during a small explosive event on 5 September 2018 from the New South-East Crater (NSEC). This explosive event generated both seismic waves propagating in the ground, and acoustic pressure signals propagating in the atmosphere. We show that the DAS records catch both, as confirmed by the conventional sensors records, with seismic and acoustic frequency bands being 0.5-10 Hz and 18-25 Hz respectively. The amplitude and frequency response of the ground to the arrival and propagation of the seismo-acoustic wave along the fibre reveal spatial characteristic patterns that reflect local geological structures.
Here, we focus on the analysis of strain rate records along a 1.3 km-long fibre optic cable deployed in Piano delle Concazze. This area is affected by several North-South trending faults and fractures, which accommodate extension of the nearby North-East Rift zone, where magmatic intrusions often occur. Segments of these faults and fractures are hidden by lava flows and volcano-clastic deposits produced by effusive and explosive Etna activity.
We identify and characterize volcano-related dynamic strain changes at an unprecedented high spatial (2 m) and temporal (1 kHz) sampling over a broad frequency range using DAS record analysis. The validation of the iDAS response is performed using dense network of conventional sensors (comprising 5 broadband seismometers, 15 short-period geophone and two arrays of 3 infrasound sensors) deployed along the fibre optic cable. We find excellent agreement, thus demonstrating for the first time the capability of DAS technology in sensing seismic waves generated by volcanic events.
The frequent and diverse Etna activity during the acquisition period (30 August - 16 September 2018) allowed us to record a wide variety of signals and, hence, to test the response of iDAS to several volcanic processes. We focus the analysis on the signals recorded during a small explosive event on 5 September 2018 from the New South-East Crater (NSEC). This explosive event generated both seismic waves propagating in the ground, and acoustic pressure signals propagating in the atmosphere. We show that the DAS records catch both, as confirmed by the conventional sensors records, with seismic and acoustic frequency bands being 0.5-10 Hz and 18-25 Hz respectively. The amplitude and frequency response of the ground to the arrival and propagation of the seismo-acoustic wave along the fibre reveal spatial characteristic patterns that reflect local geological structures.