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Abstract:
The impact of faults on the contemporary stress
field in the upper crust has been discussed in various studies.
Data and models clearly show that there is an effect, but so
far, a systematic study quantifying the impact as a function of
distance from the fault is lacking. In the absence of data, here
we use a series of generic 3-D models to investigate which
component of the stress tensor is affected at which distance
from the fault. Our study concentrates on the far field, lo-
cated hundreds of metres from the fault zone. The models
assess various techniques to represent faults, different mate-
rial properties, different boundary conditions, variable orien-
tation, and the fault’s size. The study findings indicate that
most of the factors tested do not have an influence on ei-
ther the stress tensor orientation or principal stress magni-
tudes in the far field beyond 1000 m from the fault. Only in
the case of oblique faults with a low static friction coeffi-
cient of μ = 0.1 can noteworthy stress perturbations be seen
up to 2000 m from the fault. However, the changes that we
detected are generally small and of the order of lateral stress
variability due to rock property variability. Furthermore, only
in the first hundreds of metres to the fault are variations large
enough to be theoretically detected by borehole-based stress
data when considering their inherent uncertainties. This find-
ing agrees with robust stress magnitude measurements and
stress orientation data. Thus, in areas where high-quality and
high-resolution data show gradual and continuous stress ten-
sor rotations of > 20◦ observed over lateral spatial scales of
10 km or more, we infer that these rotations cannot be at-
tributed to faults. We hypothesize that most stress orienta-
tion changes attributed to faults may originate from different
sources such as density and strength contrasts.
