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Journal of Geophysical Research – Solid Earth
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Supporting Information for
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Intraplate rotational deformation induced by faults
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Neta Dembo1,2, Yariv Hamiel2, Roi Granot1
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1Department
of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel,
2Geological Survey of Israel, Jerusalem, Israel.
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Contents of this file
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Introduction
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The supporting information presented in Text S1 discusses the robustness of our elastic
modeling approach Text S2 provides a detailed description of the interseismic modeling
parameters and results.
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Figure S1 provides a comparison between the rotational patterns predicted by an elastic halfspace solution to those of both elastic and elasto-plastic finite element models.
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Figure S2 provides the same figures as in figure 2a-b in the main article, but for a right lateral
strike-slip fault.
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Figure S3 provides 40Ar/39Ar step heating results used to determine basalt ages. Dating
measurements and analysis were performed by the New Mexico Geochronological Research
Laboratory at the New Mexico Institute of Mining and Technology.
Text S1 and S2
Figures S1 to S3
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Text S1.
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To assess the viability of our elastic modeling approach we compared the results of the long-
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term rotational patterns predicted by an elastic half-space solution to the results of both elastic
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and elasto-plastic finite element models.
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We modeled a synthetic left-lateral strike slip fault extending to a length of 100 km using a slip
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rate of 2.5 mm/yr. The elastic half-space solution was modeled using a Poisson ratio of 0.25
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and given a fault extending from the surface downwards to a depth of 1000 km (in order to
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mimic infinite fault width). The finite element modeling is done using COMSOL commercial
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software. The computational domain that mimics the lithosphere used for the finite element
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models has a size of 200 x 200 x 100 km3 with element length of ~2 km near fault and
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increasing towards the block boundaries. Boundary conditions include tangential
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displacements at the outermost lateral boundaries, which are parallel to the fault, and zero
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displacement at the bottom of the block. A Poisson ratio of 0.25 and a Young’s modulus of 75
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Mpa are used for the elastic finite element model. The same elastic moduli are used in the
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elasto-plastic model until a yield stress of 150 MPa. After this yield stress an effective Young’s
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modulus of 25 Mpa is defined.
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Comparison between the deformation fields predicted by the three models resulted in similar
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rotation patterns (Figure S1). Therefore, the results from our synthetic modeling suggest that
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our approach using an elastic half-space dislocation model can be used to simulate patterns of
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permanent deformation near faults.
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Text S2.
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rate of 4.9 mm/yr (in the range of 3.8-4.9 mm/yr) and locking depth of 15.9 km (in the range of
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14.1-15.9 km) along the DSF segment found south of the junction with the CGFS (Figure 8) to a
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slip rate of 3.8 mm/yr (in the range of 3.8-4.9 mm/yr) and locking depth of 14.1 km (in the range
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of 14.1-15.9 km) along the DSF segment north of this junction. Due to small number of GPS
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stations in the eastern side of this junction, we cannot point to an exact location where this
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change in slip occurs, also we cannot rule out the idea that this transition is gradual.
Our best fitting interseismic model for the DSF in northern Israel shows a decrease from a slip
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Our study confirms Sadeh et al. [2012] slip rate of 1.1±0.4 mm/yr along the Carmel Fault, which
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is also consistent with the decrease in slip along the DSF (slip direction is in azimuth of ~6˚). We
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infer a best fitted locking depth of 5 km (in the range of 5-15 km) for this fault. The model also
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indicates a locking depth of 5 km (in the range of 5-15 km) along the Gilboa Fault together with
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a slip rate of 0.75±0.75 mm/yr (slip direction in azimuth of ~31˚), which is in agreement with
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geological slip rates reported for this fault by Hatzor and Reches [1990].
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Based on our modeling, interseismic rotations are relatively insensitive to locking depths
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confined between 5 and 16 km and to the range of examined slip rates along the DSF (3.8-4.9
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mm/yr) and CGFS (up to 1.5 mm/yr). However, the RMS value of the best fitting model of the
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DSF fault alone is still higher than the RMS of the model including both DSF and CFS faults.
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This indicates that by adding the CFS faults to the model the fit to the GPS data improves,
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which also strengthens the theory of slip portioning from the DSF to CGFS.
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Figure S1. Rotation rates predicted by: (a) elastic half space model, (b) elastic finite element
model, (c) elasto-plastic finite element model. A detailed description of the models setup is
found in Text S1 of the auxiliary material.
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Figure S2. Surface vertical axis rotation rates caused in response to motion of synthetic faults.
(a) An interseismic model of a vertical right-lateral strike slip fault locked to 15 km depth. (b) A
total deformation slip model of a vertical right-lateral strike slip fault that slips up to the
surface. Both faults were arbitrary set to a length of 200 km using a slip rate of 5 mm/yr. The
parameters were chosen to best reflect and emphasize the differences between the different
styles of deformation.
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Figure S3. 40Ar/39Ar step heating of Neogenic basalts. Arrows show the steps included by the
plateau age calculation. Dating measurements and analysis were performed by the New
Mexico Geochronological Research Laboratory at the New Mexico Institute of Mining and
Technology. MSWD stands for the mean sum weighted deviates.
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