The new IMGC-02 transportable absolute gravimeter: measurement apparatus and applications in geophysics and volcanology

G. D’Agostino, S. Desogus, A. Germak, C. Origlia, D. Quagliotti, G. Berrino, G. Corrado, V. D’errico, G. Ricciardi


The research carried out at the Istituto Nazionale di Ricerca Metrologica (formerly Istituto di Metrologia «G.
Colonnetti») aiming to develop a transportable ballistic absolute gravimeter ended with a new version of the instrument,
called the IMGC-02. It uses laser interferometry to measure the symmetrical free rising and falling
motion of a test mass in the gravity field. Providing the same accuracy achieved with previous versions, the instrumental
improvements mainly concern size, weight, data processing algorithms and operational simplicity.
An uncertainty of 9 ?Gal (1 ?Gal=1×108 m·s?2) can be achieved within a single observation session, lasting
about 12 h, while the time series of several observation sessions show a reproducibility of 4 ?Gal. At this level,
gravity measurements provide useful information in Geophysics and Volcanology. A wide set of dynamic
phenomena, i.e. seismicity and volcanic activity, can produce temporal gravity changes, often quite small, with
an amplitude ranging from a few to hundreds of microgals. Therefore the IMGC absolute gravimeter has been
employed since 1986 in surveying the Italian active volcanoes. A brief history of the gravimeter and the description
of the new apparatus, together with the main results of ongoing applications in Geophysics and Volcanology
are presented.


gravity;absolute gravimeter;measurements;geophysics;volcanology

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