The scaling of seismic energy with moment: Simple models compared with observations
Abstract
The scaling between small and large earthquakes remains an unresolved issue in seismology. The predominant hypothesis is the rupture process is self-similar, leading to predictions that source parameters such as apparent stress are the same for all earthquakes. As digital broadband data has become widely available, a number of published empirical studies have challenged self-similarity, though the evidence remains mixed. Using simple point source models in the time and frequency domains, we review the predicted scaling behavior of earthquake energy and other source parameters, under self- and non-self-similar assumptions. The models show self-similar scaling leads to some testable hypotheses, including the constancy of apparent stress and the invariance of spectral shape under a particular frequency transformation, regardless of the true (and perhaps unknown) source time function. We also review the problems posed by measurement errors in determining seismic energy and the limited magnitude ranges of events within given studies to answering the scaling question. To address these problems we apply multiple techniques to the 1999 Hector Mine California earthquake sequence. For two regional wave types, direct Lg and scattered coda waves, we examine spectral scaling using both seismic energy, and source shape invariance. The results show the Hector Mine sequence exhibits non-self-similar scaling with apparent stress increasing with moment approximately as Mo 0.14. Finally we briefly present four general scaling models, one self-similar with high variance, the others non-self-similar, which appear to be consistent with the earthquake apparent stress behavior that has been observed to date.
- Publication:
-
Geophysical Monograph Series
- Pub Date:
- 2006
- DOI:
- 10.1029/170GM05
- Bibcode:
- 2006GMS...170...25W