Strategies in the processing and analysis of continuous gravity record in active volcanic areas: the case of Mt. Vesuvius

U. Riccardi, G. Berrino, G. Corrado, J. Hinderer

Abstract


This research is intended to describe new strategies in the processing and analysis of continuous gravity records
collected in active volcanic areas and to assess how permanent gravity stations can improve the geophysical
monitoring of a volcano. The experience of 15 years in continuous gravity monitoring on Mt. Vesuvius is discussed.
Several geodynamic phenomena can produce temporal gravity changes. An eruption, for instance, is associated
with the ascent of magma producing changes in the density distribution at depth, and leading to ground
deformation and gravity changes The amplitude of such gravity variations is often quite small, in the order of
10-102 nms-2, so their detection requires high quality data and a rigorous procedure to isolate from the records
those weak gravity signals coming from different sources. Ideally we need gravity signals free of all effects
which are not of volcanic origin. Therefore solid Earth tide, ocean and atmospheric loading, instrumental drift
or any kind of disturbances other than due to the volcano dynamics have to be removed. The state of the art on
the modelling of the solid Earth tide is reviewed. The atmospheric dynamics is one of the main sources precluding
the detection of small gravity signals. The most advanced methods to reduce the atmospheric effects on gravity
are presented. As the variations of the calibration factors can prevent the repeatability of high-precision measurements,
new approaches to model the instrumental response of mechanical gravimeters are proposed too.
Moreover, a strategy for an accurate modelling of the instrumental drift and to distinguish it from longterm gravity
changes is suggested.

Keywords


time gravity changes;gravity record;volcanic processes;air pressure admittance

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References


DOI: https://doi.org/10.4401/ag-3039

Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X