Periodic or quasiperiodic earthquake recurrence on individual faults, as predicted by the elastic rebound model, is not common in nature. Instead, most earthquake sequences are complex and variable, and often show clusters of events separated by long but irregular intervals of quiescence. Such temporal patterns are especially common for large earthquakes in complex fault zones or regional and global fault networks. Mathematically described as the Devil’s Staircase, such temporal patterns are a fractal property of nonlinear complex systems, in which a change of any part (e.g., rupture of a fault or fault segment) could affect the behavior of the whole system. We found that the lengths of the quiescent intervals between clusters are inversely related to tectonic-loading rates, whereas earthquake clustering can be attributed to many factors, including earthquake-induced viscoelastic relaxation and fault interaction. Whereas the underlying causes of the characteristics of earthquake sequences are not fully known, we attempted to statistically characterize these sequences. We found that most earthquake sequences are burstier than the Poisson model commonly used in probabilistic seismic hazard analysis, implying a higher probability of repeating events soon after a large earthquake.
At 3:42 a.m. (UTC+8) on July 28, 1976, a magnitude (M s ) 7.8 earthquake hit Tangshan, an industrial city in North China just 150 km east of Beijing, causing a surface rupture >47-km long (Figure 1) (Guo et al., 2017). About 15 h later, a second shock, of M s 7.1, occurred ∼40 km to the east-northeast on a different fault and ruptured surface >6-km long (Guo et al., 2017). These two events, together referred to as the Great Tangshan earthquake, obliterated the city of Tangshan and killed >240,000 people, making it the deadliest earthquake of the 20th century (Chen et al., 1988). More than 40 years have passed, but the memory of the devastation remains fresh. Thus, a series of moderate (M ≥ 4.5) earthquakes in recent years near the 1976 Tangshan earthquake rupture zone, including an M s 5.1 event on July 12, 2020, have raised social concern and scientific debate: are these events aftershocks of the Great Tangshan earthquake? Or are they indicators of stress buildup for future large earthquakes in Tangshan or somewhere in North China? North China, or the geologically defined North China block, includes the North China Plain and the mountain ranges and the Ordos Plateau to the west. It is an Archean craton that was reactivated during the
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.