Evidence of Earthquake Triggering by the Solid Earth Tide based on Global Data

Abstract:

Abstract:The correlation between the earth tide and earthquake occurrence has been analyzed using the largest global earthquake catalog available (the NEIC catalog with magnitude 4 or larger from 1900 to 2014). The results show that the number of earthquakes, which occurred around the extreme value point of the earth tide, is larger than that occurred on other phases. The phase selectivity parameter (p) evaluated based on the Schuster’s method varies inversely as the significant level of the correlation between the earth tide and earthquake occurrence. First, the earthquakes are classified in to three types by magnitude: type a (M≥6.0), type b (5.0≤M＜6.0) and type c (4.0≤M<5.0). The values of p are 30.22%, 24.2% and 10.5% for type a, b, and c, respectively. Second, the earthquakes of type c are divided into two subgroups by depth of the earthquakes, and their values of p for shallow (depth＜70 km) and deep (depth≥70 km) earthquakes are 6.5% and 95.67%, respectively. These results suggest that the shallow (<70km) and small (M<5.0) earthquakes correlate better with the earth tide than the deep and large earthquakes do.

Key words: earth tide, earthquake, triggering