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Tobyáš, Vladimír

doi:10.1023/a:1023305810018

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…The vibrating platform is an ideal tool to characterize the dynamic behavior of the mechanical components of gravity instruments (Tobyáš et al 1999;Aliod et al 2003). We calibrated the spring gravimeters by analyzing their response to controlled harmonic accelerations exerted by the vibrating platform.…”

Section: Ground Vibrations and Gravimeter Responsementioning

confidence: 99%

Characterization of the response of spring-based relative gravimeters during paroxysmal eruptions at Etna volcano

et al. 2014

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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 the instrumental effects due to ground vibrations such as those that accompany explosive activity. We simulated the performances of relative gravimeters with 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 (Lafayette, CO, USA) and the Scintrex CG-3 M#9310234 (Concord, ON, Canada). The experiment results highlight that the vibrations resembling the seismic waves propagated during paroxysmal events cause an amplitude response in the gravity readings on the order of several hundred microgals (μGal). Generally, the relationship between the vibrations and the gravimeter response is nonlinear, with a fairly complex dependence on the frequencies and amplitudes of the signals acting on the gravimeters.

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Section: Ground Vibrations and Gravimeter Responsementioning

confidence: 99%

Characterization of the response of spring-based relative gravimeters during paroxysmal eruptions at Etna volcano

et al. 2014

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Balancing bulk gas accumulation and gas output before and during lava fountaining episodes at Mt. Etna

Carbone

Zuccarello

Messina

et al. 2015

Sci Rep

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We focus on a sequence of 9 lava fountains from Etna that occurred in 2011, separated by intervals of 5 to 10 days. Continuous measurements allowed to discover the occurrence of gravity decreases before the onset of most fountaining episodes. We propose that the gravity changes are due to the pre-fountaining accumulation of a foam layer at shallow levels in the plumbing system of the volcano. Relying on the relationship between amount of gas trapped in the foam and amount of gas emitted during each episode, we develop a conceptual model of the mechanism controlling the passage from Strombolian to lava fountaining activity. Gas leakage from the foam layer during the late stages of its accumulation increases the gas volume fraction at upper levels, thus inducing a decrease of the magma-static pressure in the trapping zone and a further growth of the foam. This feedback mechanism eventually leads to the collapse of the foam layer and to the onset of lava fountaining. The possibility to detect the development of a foam layer at depth and to set quantitative constraints on the amount of trapped gas is important because of the implications for forecasting explosive eruptions and predicting their intensity.

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Detection of Long Period Seismic Events by Using a Portable Gravity Meter, gPhone

Lee¹,

Seo²,

Eom³

et al. 2015

Geophysics and Geophysical Exploration

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Cited by 3 publications

References 5 publications

Characterization of the response of spring-based relative gravimeters during paroxysmal eruptions at Etna volcano

Characterization of the response of spring-based relative gravimeters during paroxysmal eruptions at Etna volcano

Balancing bulk gas accumulation and gas output before and during lava fountaining episodes at Mt. Etna

Detection of Long Period Seismic Events by Using a Portable Gravity Meter, gPhone

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