ABSTRACT
Abstract-The worldwide catalogs ISC and NEIC (total amount of events from 1966 is more than 200000) were used in a search of spatial and temporal distribution of earthquakes (EQ). The distributions of the events between Northern and Southern parts of the Pacific region are different for various magnitude levels (4 ~ Mb < 4.5; 4.5 ~ Mb < 5; 5 ~ Mb < 5.5; 5.5 ~ Mb < 6.0; 6 ~ Mb < 6.5; 6.5 ~ Mb). The distribution-free test (run test with significant level 1%) was used for existence proof of the non-random component into time sequences. The time sequences of EQ switching between the Northern and Southern parts of the Pacific region contain a statistically significant non-random component for the events with 4.0 ~ Mb < 6.0. Then time sequences for each magnitude level were subdivided into several subintervals. The statistical validity of nonrandom component existence into subintervals remains for the most of magnitude levels. The digital model (superposition of random processes and a periodic process) was proposed. A set of calculating experiments using this model was carried out and the conditions for statistical validity of the periodic component in compound process were defined. It was found that the statistical validity of the periodic component according to the run test depends on the ratio frequency of the periodic component and the size of the sample sequence. Then data in each magnitude range were subdivided in two groups: deep earthquakes (H > 70 km) and shallow earthquakes (H ~ 70 km). It was found that the non-random component does not exist in deep earthquakes. In contrast, it is clearly manifested in time distribution of the shallow events. The calculating experiments enable us to comprehend a particular feature of the observation data: absence of the non-random component for the magnitude level Mb > 6; disappearance of the non-random component after subdividing into subintervals (with duration 4 and 2 years) for some magnitude levels. The obtained results indicate that external periodical factors can influence the process of earthquake generation.
