Rissc Lab - Seismic source

Seismic Source

Seismic source

A seismic signal that propagates from an earthquake source to a specific seismic recorder carries with it coded information on the source and the propagation medium. To understand the physical processes of the source, there is thus the need for accurate knowledge of the propagation. At large distances with respect to the dimensions of a fault, the coherent information on the source is averaged, and a few parameters are sufficient to characterize it, such as the moment and the location of the hypocenter. Records near the source allow, instead, an investigation of its details. Two descriptions of the rupture process are possible. Kinematic models cannot describe the physical processes of the fracture, but they use a few macroscopic parameters for the interpretation of the data, such as the rupture velocity, the slip and the rise-time. The dynamic models of the source, instead, interpret the fracture process through an energy balance.

In this sector, the RISSC is involved in the following activities:

Development of determination techniques in real-time for the magnitude and the focal mechanism, for early warning applications;
Development of non-linear motion-inversion techniques of a source, like the multiscale technique with genetic algorithms and the isocrone technique;
Use of kinematic/dynamic source models for deterministic studies of ground-motion scenarios following a large earthquake, for seismic hazard evaluation;
Development of the numerical technique of the spectral elements, for the simulation of dynamic propagation of seismic rupture;
Use of numerical methods of dynamic propagation of a fracture for the interpretation of physical phenomena, such as the role of geometry in rupture dynamics and in seismic radiation, and analysis of the correlation between seismic propagation in the first seconds from the rupture and the final size of the rupture itself.