A laboratory perspective on earthquakes: from the nano to the magathrust scale – vendredi 22 mars, 14h30 Amphi D
Reliable estimations of the seismic hazard in a region requires the prediction of the size, location and magnitude of future earthquake events. However, such prediction is hindered by limited constraints on the real earthquakes physics, which is governed by the interplay of friction, healing, stress perturbations and strain events on faults operating at different spatial and temporal scales. Not all these evolving variables are directly accessible from either seismological, geodetic observations or filed survey so that laboratory investigations are becoming increasingly relevant to provide a ready access to the experimental seismic source.
At INGV (Rome, IT) we avail of SHIVA (Slow to HIgh Velocity Apparatus), the most powerful rotary shear apparatus installed worldwide able to apply close to natural earthquake deformation conditions (slip velocities of up to 10 m/s, accelerations of 65 m/s2, a nominally infinite slip and normal stresses larger than 30 MPa) on fault rock samples (50 mm of diameter) under a variety of environmental setup (e.g. room humidity, vacuum, fluid pressure). We simulate the entire seismic cycle on fault materials either form outcrops, cores exhumed from deep drilling projects (e.g. IODP JRSO expedition 362 Sumatra seismogenic zone) or selected lithologies ( e.g. Carrara marble, 99% calcite).
Our investigations spans from the nanoscale to the large scale of megathrusts availing of integrated geological, experimental and numerical approaches. Our aim is twofold in discussing the micro-physics of laboratory earthquakes – that intimately govern natural fault rocks behavior – and in deepening our previous knowledge of fault stability heavily challenged by the unexpected behaviour of recent tsuamigenic events like the 2004 Sumatra and 2011 Tohoku earthquakes.