Journal
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
Volume 119, Issue 4, Pages 3678-3699Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1002/2013JB010347
Keywords
-
Categories
Funding
- UK Natural Environment Research Council (NERC) through the FaultLab project [NE/I028017/1]
- Centre for Observation and Modelling of Earthquakes and Tectonics (COMET)
- Natural Environment Research Council [NE/I028017/1, NE/J01978X/1, NE/K010867/1, come30001] Funding Source: researchfish
- NERC [come30001, NE/J01978X/1, NE/I028017/1, NE/K010867/1] Funding Source: UKRI
Ask authors/readers for more resources
GPS data before and after the 1999 Izmit/Duzce earthquakes on the North Anatolian Fault Zone (Turkey) reveal a preseismic strain localization within about 25 km of the fault and a rapid postseismic transient. Using 3-D finite element calculations of the earthquake cycle in an idealized model of the crust, comprising elastic above Maxwell viscoelastic layers, we show that spatially varying viscosity in the crust can explain these observations. Depth-dependent viscosity without lateral variations can reproduce some of the observations but cannot explain the proximity to the fault of maximum postseismic velocities. A localized weak zone beneath the faulted elastic lid satisfactorily explains the observations if the weak zone extends down to midcrustal depths, and the ratio of relaxation time to earthquake repeat time ranges from similar to 0.005 to similar to 0.01 (for weak-zone widths of similar to 24 and 40 km, respectively) in the weakened domain and greater than similar to 1.0 elsewhere, corresponding to viscosities of similar to 10(18 +/- 0.3) Pa s and greater than similar to 10(20) Pa s. Models with sharp weak-zone boundaries fit the data better than those with a smooth viscosity increase away from the fault, implying that the weak zone may be bounded by a relatively abrupt change in material properties. Such a change might result from lithological contrast, grain size reduction, fabric development, or water content, in addition to any effects from shear heating. Our models also imply that viscosities inferred from postseismic studies primarily reflect the rheology of the weak zone and should not be used to infer the mechanical properties of normal crust.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available