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.

Zakharova, O., Hainzl, S., Lange, Dietrich and Enescu, B. (2017) 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. Pure and Applied Geophysics, 174 (1). pp. 77-102. DOI 10.1007/s00024-016-1408-7.

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Abstract

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.

Document Type: Article
Research affiliation: GFZ
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00024-016-1408-7
ISSN: 0033-4553
Projects: GeoSim
Date Deposited: 05 Dec 2016 09:17
Last Modified: 01 Feb 2019 15:06
URI: http://oceanrep.geomar.de/id/eprint/35022

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