Spatiotemporal Symmetry and Trend Assessment of Ms≥7.0 Earthquakes in the Sichuan-Yunnan Region of China

Commensurability information, a butterfly diagram and a commensurability structure system were used to analyse the spatiotemporal symmetry and to assess the trends of Ms≥7.0 earthquakes in the Sichuan-Yunnan region of China. The results show that the next earthquake may occur in 2020 or 2021, as seismic signals are strong. Analysing the characteristics of epicentre spatial migration, there is a significant synchrony and symmetry between the latitudinal and longitudinal epicentre migrations. The symmetry axis is 30°N in latitude and 101.5°E in longitude. There is a northeast–southwest strike symmetry axis, and the next epicentre may migrate toward the southwest (i.e., south of 30°N and west of 101.5°E); the calculated strike symmetry axis is Y=3.5X-329. By grouping earthquake disaster events, the spatial migration pathways of the epicentres regularly exhibit jump-migration and sequential-migration. The migration distributions over the symmetry axis quadrants are ‘uniform-discrete’ and ‘concentrated-dispersion’.