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Periodic Report Summary 1 - GTRACE (Dynamics of Terrestrial Gravity Perturbations)

The main objective of GTrace was to improve models of terrestrial gravity fluctuations in the frequency range 10mHz to 30Hz. More specifically, the goals were to (1) analytically and numerically investigate gravity noise in gravitational-wave detectors, and how to mitigate it, and (2) to calculate accurate models of gravity perturbations from earthquakes.

The researcher has published as first author of two papers the analytical computation of gravity perturbations from fault ruptures in full-space and also in half-space in Geophysical Journal International. In recognition of his leading position in the field, the researcher has been invited to write a review article on terrestrial gravity perturbations, published on Living Reviews of Relativity. The review includes new calculations of gravity perturbations from turbulence, the effect of seismic scattering on gravity noise, and new insight in cancellation of gravity noise in gravitational-wave detectors.

In collaboration with a team constructing the atom-interferometric detector MIGA, the researcher improved models of gravity perturbations at low frequencies, i.e., between 10mHz and 1Hz. The result is that such detectors will be strongly limited by atmospheric gravity noise even when constructed underground.

The work on gravity perturbations from earthquakes led to a publication, where the observation of the gravity change from the Tohoku-Oki earthquake within a few tens of seconds after the onset of a fault rupture was reported. Observed gravity changes are consistent with theoretical predictions. This paper also serves as proof-of-principle that gravity sensors with improved sensitivity can in the future be used in earthquake-early-warning systems.

Reported by

Universita' degli Studi di Urbino Carlo Bo


Life Sciences
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