Spatial Variations of Aftershock Parameters and their Relation to Geodetic Slip Models for the 2010 Mw8.8 Maule and the 2011 Mw9.0 Tohoku-oki Earthquakes
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- 作者：O. Zakharova ; S. Hainzl ; D. Lange ; B. Enescu
- 刊名：Pure and Applied Geophysics
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：174
- 期：1
- 页码：77-102
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Geophysics/Geodesy;
- 出版者：Springer International Publishing
- ISSN：1420-9136
- 卷排序：174
文摘
Recent development in analysis tools and deployments of the geodetic and seismic instruments give an opportunity to investigate aftershock sequences at local scales, which is important for the seismic hazard assessment. In particular, we study the dependencies between aftershock sequences properties and deformational/geological data on a scale of the rupture extension of megathrust earthquakes. For this goal we use, on one hand, published models of inter-, co- and postseismic slip and geological information and, on the other hand, aftershock parameters, obtained by fitting a modified Epidemic Type Aftershock Sequence (ETAS) model. The altered ETAS model takes into account the mainshock rupture extension and it distinguishes between primary and the secondary aftershock triggering involved in the total seismicity rate. We estimate the Spearman correlation coefficients between the spatially distributed aftershock parameters estimated by the modified ETAS model and crustal physical properties for the Maule 2010 Mw8.8 and the Tohoku-oki 2011 Mw9.0 aftershock sequences. We find that: (1) modified ETAS model outperforms the classical one, when the mainshock rupture extension cannot be neglected and represented as a point source; (2) anomalous aftershock parameters occur in the areas of the reactivated fault systems; (3) aftershocks, regardless of their generation, tend to occur in the areas of high coseismic slip gradient, afterslip and interseismic coupling; (4) aftershock seismic moment releases preferentially in regions of large coseismic slip, coseismic slip gradient and interseismically locked areas; (5) b value tends to be smaller in interseismically locked regions.