by
Prof.Carlo Doglioni(Presidente INGV e "La Sapienza")
→
Europe/Rome
Aula Conversi (Dipartimento di Fisica - Ed. G. Marconi)
Aula Conversi
Dipartimento di Fisica - Ed. G. Marconi
Description
The mechanisms governing plate motion are still unsolved. Bottom up or top down thermal Rayleigh-Bénard convection models are usually assumed to drive geodynamics. However, there are a several inconsistencies, and plate boundaries show a systematic asymmetry that appears to be controlled by Earth’s rotation and tidal drag. Seismicity is concentrated in the shallow crust and at plate boundaries. It decreases toward polar areas indicating an astronomical tuning in its development. The usual assumption is that earthquakes nucleate when the static friction over a surface is overtaken by the differential stress generated by elastic energy. This model also suggests regularity in earthquake occurrence, that is the basis for the seismic hazard maps based on the probabilistic approach. In reality we see that the bit of earthquakes is much more random and the recurrence time may be an elusive concept.
