Earthquakes within Earthquakes: Patterns in Rupture Complexity

Abstract

<p>Earthquake source time functions carry information about the complexity of seismic rupture. We explore databases of source time functions of earthquakes and find that source time functions are composed of distinct peaks that we call subevents. We observe that earthquake complexity, as represented by the number of subevents, grows with earthquake magnitude. We find that subevent magnitudes are nearly proportional to their corresponding main event magnitude. We show that the main event magnitude can be estimated after observing only the first few subevents.</p>

Resolving Complicated Faulting Process Using Multi‐Point‐Source Representation: Iterative Inversion Algorithm Improvement and Application to Recent Complex Earthquakes

“…The trend of these reference curves indicates the rupture concentration, with rupture at the top left corner corresponding to higher concentration (lower b ‐value). Danré et al () analyze source time functions of earthquakes of different scales and used stripping method to decompose STFs into subevents. They find a systematic complexity growth with earthquake magnitude.…”

A probabilistic view on rupture predictability: all earthquakes evolve similarly

“…Other models also suggest early predictability, but only after several seconds. For example, Melgar & Hayes (2017) argue that ruptures of large events propagate as self-healing pulses, and that pulse properties allow identification of very large events after ∼15 s. Support for such theories has been provided by the analysis of, e.g., waveform onsets (Ellsworth & Beroza, 1995), moment rate functions (Danré et al, 2019), and early ground motion parameters (Colombelli et al, 2020).…”

“…While reaching contradicting conclusions, predictability studies often follow the same principle: analyzing correspondences between earthquake size and real time observables (Ellsworth & Beroza, 1995;Danré et al, 2019;Colombelli et al, 2020;Meier et al, 2017;Ide, 2019;Trugman et al, 2019). Earthquake size is commonly quantified by seismic moment/moment magnitude, as large, high quality catalogs thereof are openly available (Ekström et al, 2012).…”

“…A cross section view of the three different options at fixed time is shown in Figure S2a. common practice is calculating parametric fits between magnitude and observables, and assessing at which time they become significant using standard deviations (Melgar & Hayes, 2017;Danré et al, 2019;Colombelli et al, 2020;Meier et al, 2017;Olson & Allen, 2005;Noda & Ellsworth, 2016;Zollo et al, 2006). However, this point-estimator approach hides the residual distribution and thereby potentially obscures distinct modes of rupture predictability, especially when distributions are non-Gaussian (see Figure S1 for a toy example illustrating the importance of this restriction).…”

The 2019 MW 5.7 Changning Earthquake, Sichuan Basin, China: A Shallow Doublet With Different Faulting Styles

“…Earthquake doublets provide clues for understanding complex fault systems (e.g., Danré et al, ; Hicks & Rietbrock, ; Lay et al, ). Particularly challenging are closely spaced doublets whose subevents have unequal focal mechanisms, separated just by a few kilometers and a few seconds, intuitively suggesting a causal relationship between the involved faults.…”