I'm interested in - the origin, - the measurement of hysteretic energy dissipated under stress - and its role in material damage.

Since the 1800s, Lagrangian mechanics has associated hysteresis with energy dissipation, but the formalism used is at best consistent with observations at very high strain rates, when explosive stresses are reached. Under these conditions, hysteresis no longer exists. Hysteresis only occurs at lower strain rates and is due to extended defects. The measurement of hysteresis involves the study of pre-seismic phenomena, when defects are annihilated by deformation, temperature rise and very high energy electromagnetic emissions. These emissions are at the origin of the ionospheric disturbances observed after earthquakes. These processes are described by an equation of state, which has the advantage of predicting material ageing kinetics and lifetime. The experimental technique of measuring hysteretic energy allows the factors of the equation of state to be measured and the factors of an explosion probability law to be derived.

Before this approach can be applied to earthquake prediction, its likelihood of detecting all known pre-seismic and seismic effects, such as the effect of plate velocities on earthquake frequency and magnitude, must be assessed.

Claude Le Gressus