The Earth's rotation-triggered earthquakes preceding the occurrence of the 2019 M7.1 Ridgecrest earthquake

Abstract

For earthquakes (M ≥ 2.0) occurring in and around the aftershock zone of the M7.1 Ridgecrest earthquake between January 2000 and June 2019, we analyzed the correlation between the phase of Earth's rotation and the occurrence of earthquakes. The Schuster's test and the two-rate Poisson model were used to statistically examine the correlation between the phase of Earth's rotation and the occurrence of earthquakes. For the Schuster's test, the results were judged based on the P-value. When the P-value is smaller, the correlation is higher. In general, if P ≤ 5%, the correlation is significant. For the two-rate Poisson model, the results were evaluated by R. When the 95% confidence lower limit on R (RL ) is over one, earthquakes could be non-random. We calculated the temporal variation on the P-value for earthquakes that occurred in the study region and found lower P-values, corresponding to significant correlation for earthquakes (2.0 ≤ M ≤ 2.4) occurring before the M7.1 event. When the P-value reached to the lowest, the earthquake nucleated when the Earth's acceleration of rotation is increasing or near the peak acceleration. This correlation is also confirmed by the two-rate Poisson model. The spacial distribution of the P-values for earthquakes (2.0 ≤ M ≤ 2.4) occurring from Jul. 2013 to Jun. 2019 shows that areas of low P-value were located mainly in and around the northwest segment of the aftershock zone of the M7.1 Ridgecrest earthquake. The lower P-value obtained in this study emphasises that the Earth's rotation can triggered earthquakes in and around the aftershock zone prior to the M7.1 Ridgecrest earthquake and hence it may be considered as one of the precursors.