Crustal monitoring through ambiental seismic noise – induced seismicity in the Castanhão – CE Dam and siemisicity in the San Peter e Saint Paul archipelago
Interferometry; passive monitoring; Castanhão Dam; seismic noise.
Seismogenic regions constantly suffer from the variation of stress and the generalized predominance of fractures caused during earthquakes. This fracture, as well as the hydromechanical factors, end up creating areas of low velocity during the earthquake, in which we can use as an evaluation parameter in seismological monitoring. In addition, the seismic velocity change reveals relevant information about the seismic effect, such as the process of relaxation (healing) of the medium. Since stable, the seismic noise wavefield can be used in monitoring these structural changes. Through interferometry it is possible to recover signals that contain the structural response of
the medium (Green Function) from cross-correlations of noise between two stations. In addition, autocorrelations of the noise wavefield recorded in a single station can also be used to monitor media changes. In this way, the present research proposes to use the signal interferometry tool in the recovery of the Green 's empirical function as an
alternative for the crustal monitoring of seismogenic regions, initially aiming to establish a relation between the hydromechanical factors and the seismicity induced by the Castanhão - CE reservoir such as the quantification of the relaxation rate after erthquakes of magnitudes above 4.0ML, in this case, to a more detailed study for events occurring in the mid-oceanic ridge for the San Peter e Saint Paul archipelago.