Relationship Between the Deceleration of Earth's Rotation and Earthquakes that Occurred before the Ms 8.0 Wenchuan Earthquake

For earthquakes (M-L >= 2.5) that occurred from January 1990 to April 2008 around the M-s 8.0 Wenchuan earthquake, we investigated the correlation between the phase of Earth's rotation and the occurrence of earthquakes via Schuster's test to determine the signals that triggered earthquakes before the M-s 8.0 Wenchuan earthquake. We statistically investigated the correlation between the occurrence of earthquakes and Earth's rotation. The results were evaluated based on the P value where a smaller P value corresponded to a higher correlation between the occurrence of an earthquake and Earth's rotation. We analyzed the temporal evolution of P values for earthquakes and found that some lower P values, i.e., significant correlation, were calculated for earthquakes that occurred before the M-s 8.0 Wenchuan earthquake. Furthermore, we investigated the spatial distribution of P values along the Longmenshan fault and obtained a result exhibiting a considerably lower P value region in the northeastern part of the study area on the edge of which the epicenter of the M-s 8.0 Wenchuan earthquake was located. Among the earthquakes with lower P values, a vast majority of them occurred during the deceleration of Earth's rotation. The lower P value obtained in this study reveals Earth's rotation-triggered earthquakes within the rupture region prior to the occurrence of the M-s 8.0 Wenchuan earthquake.