Statistical test of the Load-Unload Response Ratio (LURR) signals using the Lattice Solid Model (LSM): implication to tidal triggering and earthquake prediction

Following from previous simulations of LURR using the Lattice Solid Model, statistical tests of LURR signals are carried in order to verify statistical robustness. In each test, 24 samples with the same macroscopic parameters but different random arrangements of particles are studied. Results of uniaxial compression experiments show that before the normalized time of catastrophic failure, the ensemble average LURR value rises significantly. In shearing tests, a dimensionless parameter (size of peak “tidal ” perturbation rate relative to rate of “tectonic ” loading) is found to control the correlation between earthquake occurrence and tidal stress. When this parameter is very small, nearly no correlation is found. However, when it becomes larger, the peak in the earthquake frequency probability density function shifts from being correlated with the peak in stress rate towards the peak in stress of the tidal perturbation. After removing the average triggering effect, statistics of LURR signals in shearing tests suggest that the larger events are more likely to occur when LURR is high than the smaller events, supporting the LURR hypothesis