Stress Field and Seismicity at Campi Flegrei Caldera

Abstract

Aim of this work is the study of the stress field in the Campi Flegrei caldera during the bradyseismic crisis of 1982-1984. n the first part of the work has been analysed old cretaceous and digital seismic datasets relative to 70th years, and the bradyseismic crisis of 1982-1984 where has been recorded the earthquakes linked to uplifts that interested Campi flegrei caldera during 1969-72 and 1982-84. The seismicity dataset has been used to made some analysis as location and focal mechanisms generation. The focal mechanisms are than analysed using two software to determine the principal state of stress that was predominant in that period. Then, starting from ground deformation data, relative to 1100 optical levelling measure done during the bradyseismic crisis, has been use the inversion method to modelling the source of the deformation. Has been used many model as the Mogi model, the penny shaped-crack, and the rectangular crack of Okada. Consequently, a joint inversion was applicate on ground deformation data and seismicity together to better understand the dynamic of the stress in the area.In the last part of the work, has been determined the excess of pore pressure in the Flegrean area, using focal mechanisms to study the influence of fluid pore pressure on change in the Coulomb stress of the area. Has been used the Coulomb-Navier criterion and Terakawa method (2010) to estimate the excess of pore pressure. Finally, in order to evaluate the reliability of the calculated pore pressures, was done thermo-fluid dynamic simulation and analysed the hydrothermal system of Campi Flegrei caldera. So, has been performed a series of simulation thermo-fluid dynamic injecting a flow in the system varying temperature, pressure and injection rate to model the Campi Flegrei caldera during the unrest.