Studies on Aftershocks in Taiwan: A Review

  • The studies of aftershocks of thirty M>5 Taiwan's earthquakes are reviewed
  • The studies about ten issues are presented
  • Some results are obviously different from the conventional concepts

We reviewed studies on aftershocks in Taiwan for the following topics: the spatial-temporal distributions and focal-plane solutions of aftershocks fromof thirty larger earthquakes with magnitudes > 5; the correlations between the mainshock and the largest aftershock based on dependence of the differences in magnitudes (ΔM), occurrence times (ΔT), epicenters (ΔH), and focal depths (ΔD) upon the mainshock magnitude, Mm; magnitude-dependence of p-value of Omori’s law of aftershocks; the correlation between the b-value of the Gutenberg-Richter’s frequency-magnitude law and the p-value; application of the epidemic-type aftershock sequences (ETAS) model to describe the aftershock sequence; the mechanisms of triggering aftershocks; and dynamic modeling of aftershocks. The main results are: (1) The spatial distribution of aftershocks for some earthquakes is consistent with the recognized fault; (2) Unlike Båth’s law, ΔM slightly increases with Mm; (3) ΔT does not correlate with Mm; (4) ΔD does not correlate with Mm; (5) ΔT somewhat increases with ΔD; (6) The p-value slightly increases with Mm; (7) There is a negative correlation between the b- and p-values. (8) There was seismic quiescence over a broader region of Taiwan before the 1999 Chi-Chi earthquake; (9) Both the static and dynamic stress changes trigger aftershocks; and (10) Dynamic modeling shows that a decrease in elastic modulus is a significant factor in triggering aftershocks.


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