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

Abstract

For earthquakes (ML ≥ 2.5) that occurred from January 1990 to April 2008 around the Ms 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 Ms 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 Ms 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 Ms 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 Ms 8.0 Wenchuan earthquake.