Gravity and crustal dynamics in Italy
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EARTH’S GRAVITY FIELD AND EARTH SCIENCES
Gravity and crustal dynamics in Italy Federica Riguzzi1 · Carlo Doglioni1,2 Received: 7 November 2019 / Accepted: 22 January 2020 © Accademia Nazionale dei Lincei 2020
Abstract Mapping the static gravity field in the Italian area is fundamental to identify the main lithospheric structures, to delineate the main geological elements at regional level and to infer the regional geodynamic setting. The ongoing tectonic processes highlight nevertheless the need to measure and model the time-variable gravity field, namely the dynamic gravity field, which requires increased accuracy and long time series of observations to separate the secular from the short-term variable components. The first, with a minor impact in Italy, are due to variations of ice mass balance (the viscoelastic response of the Earth to past changes in ice mass loading, and the elastic response of the Earth to present-day deglaciation), and the sealevel rise; the second are due to space/time variations of underground mass distributions, such as those related to seismic deformations, volcanic dynamics/eruptions and water transfer. Local-scale gravity studies along seismogenic faults may provide useful hints to study the seismic cycle and to unravel those areas more prone to seismic release by studying if the crustal volume is undergoing dilatancy (gravity decrease) or overpressure (gravity increase) before earthquake occurrence. This process, however, is accompanied by possible fluid migration, which can be revealed by other geophysical measurements, for example, by magnetotelluric and geoelectrical surveys. In this short paper, we briefly summarize the main sources of gravity variation providing on the same time orders of magnitude, spatial and temporal scales of their effects. Keywords Italian area · Geodynamics · Static gravity field · Deformations · Dynamic gravity field
1 Introduction Gravimetry measures the spatial and temporal variation of the Earth’s gravity field. This is useful in physical geodesy to define the Earth’s figure in size, shape and orientation, the geoid, a conventional equipotential surface of the gravity field providing the Earth’s reference models of heights. Gravimetry highlights the spatial distribution of mass in the inner Earth for geophysics and the temporal variation of mass distribution for geodynamic purposes.
This peer-reviewed paper is a contribution originated from presentations at the International Conference “Earth’s Gravity Field and Earth Sciences” held on March 22, 2019, at Accademia Nazinale dei Lincei in Rome. * Federica Riguzzi [email protected] 1
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italy
Dipartimento di Scienze della Terra, Sapienza Università, p.le Aldo Moro 5, 00185 Roma, Italy
2
The Earth’s gravity acceleration measured on the Earth’s surface undergoes small changes over space and time. An observer located on the Earth’s surface would measure gravity differences up to 5·10–3 g, due to his diffe
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