Publication Date:
2020-05-29
Description:
Gravity time sequences collected at Etna volcano by continuously recording spring-based relative gravimeters showed significant variations in temporal correspondence with paroxysmal eruptions. Since the observed gravity variations can only be partially related to subsurface mass redistribution phenomena, we investigated on the instrumental effects due to the ground vibrations as those accompanying explosive activity. We simulated the performances of relative gravimeters through laboratory experiments to estimate their response to vertical and horizontal excitations. Laboratory tests were carried out using a vibrating platform capable of accelerating the instruments with intensities and frequencies, in both the vertical and horizontal directions, observed in the ground vibrations associated with paroxysmal events. The seismic signals recorded at Etna volcano during the 10 April 2011 lava fountain were analyzed to retrieve the parameters used to drive the vibration platform. We tested two gravimeters used for Etna volcano monitoring: the LaCoste & Romberg D#185 and the Scintrex CG-3M#9310234. The experimental results highlight that vibrations, resembling the seismic waves propagated during paroxysmal events, cause an amplitude response in the gravity readings of the order of several hundred of microGals. Generally the relationship between the vibrations and the gravimeter response is non-linear with a fairly complex dependence on the frequencies and amplitude of the signals acting on the gravimeters.
Description:
Published
Description:
44
Description:
2V. Dinamiche di unrest e scenari pre-eruttivi
Description:
JCR Journal
Description:
open
Keywords:
Spring-based relative gravimeter
;
Vibrating platform
;
Volcano monitoring
;
Explosive eruptions
;
Gravity changes
;
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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