Time-scale invariances in preseismic electromagnetic radiation, magnetization and damage evolution of rocks

Y. Kawada, H. Nagahama, N. Nakamura
2007 Natural Hazards and Earth System Sciences  
<p><strong>Abstract.</strong> We investigate the time-scale invariant changes in electromagnetic and mechanical energy releases prior to a rock failure or a large earthquake. The energy release processes are caused by damage evolutions such as crack propagation, motion of charged dislocation, area-enlargement of sheared asperities and repetitive creep-rate changes. Damage mechanics can be used to represent the time-scale invariant evolutions of both brittle and plastic damages. Irreversible
more » ... modynamics applied to the damage mechanics reveals that the damage evolution produces the variations in charge, dipole and electromagnetic signals in addition to mechanical energy release, and yields the time-scale invariant patterns of Benioff electromagnetic radiation and cumulative Benioff strain-release. The irreversible thermodynamic framework of damage mechanics is also applicable to the seismo-magnetic effect, and the time-scale invariance is recognized in the remanent magnetization change associated with damage evolution prior to a rock failure.</p>
doi:10.5194/nhess-7-599-2007 fatcat:mqq3q72ugnb5jbbtup7r7nrvum