Earthquake early-warning system are automatic devices able to detect the occurence of an earthquake as soon as possible and to broadcast a regional alert before the arrival of strong seismic waves. Conventional system uses the difference between p-waves and s-waves. The deformation caused by an earthquake induces quasi-instantaneous changes in the Earth’s gravitational field, thus a gravity-based warning would be much faster with respect to conventional systems.
This thesis will focus on the search of an instantaneous gravity signal from the Tohoku 2011 earthquake, in the data recorded by a superconducting gravimeter at Kamioka (Japan) and the japanese network of broadband seismometers Fnet. We will also characterize the transient gravity signals through numerical computations based on e.g normal-mode method. Finally, we will study the feasibility of a gravity-based earthquake early warning system.