Geoscience Reference
In-Depth Information
In order to defi ne the number of station that should be added into a deformation
network or which sites should be used for that purpose is directly concerned with the
phenomenon understanding fault mechanics. Gerasimenko et al. (2000) conceived a
model for this purpose using a simple strike-slip fault model in which the deforma-
tions are parallel to the fault trace, in order to facilitate the solution. A one-dimensional
fault model with two parameters standard strike-slip model of dislocation theory in an
elastic half-space can be formulated as:
V
π
x
H
⎛
⎜
⎞
⎟
()
=−
dx
arctan
where x is the distance perpendicular to the fault, and the fault plane extends from the
surface of the half space to infinite depth, locked from the surface to H km, and freely
slipping below this depth V millimeter per year. The method suggested by Blewitt
(2000) leads to exact analytical solutions for the ideal transform fault locked down to
depth D. According to this method, to resolve the depth of locking D and the location
of the fault simultaneously, optimal station locations are at D/√3 from the a priori fault
plane. The seismogenic zone which is obtained as 12 km, derived from earthquake
depths using the information taken from KOERI earthquake catalogs (2008). In other
words, geodetic sites which are chosen and established are around 7 km away from the
fault trace. On the other hand, analysis of slip partitioning in two-fault system shows
that the resolution is optimized by including a station between faults. If the distance
between faults is greater than 2D which is approximately 30 km the resolution is lim-
ited. Design is also suitable for precise leveling on short baselines of the network in
order to increase the vertical component accuracy of position by using precise leveling
technique.
According to the optimization strategies, performed experiments, and collected
information stated above, a geodetic network has been designed in order to monitor
TF and its vicinity and interpretation strategies are discussed.
The network was designed based on the information from existing control points
and the fault trace geometry. Some additional stations were established in order to
defi ne the locking depth and slip rate of the fault trace according to the conclusions
defi ned above. Moreover, because of the possibility of the extension of the study area,
other active faults were taken into consideration in the design process. The station
names are identifi ed using four character Turkish National Fundamental GPS Network
(TNFGN) station names.
After discussions with the local administrations, 14 control stations were selected
for the network from among hundreds of possible sites. Numerous station points have
been established throughout the region, especially in last 3 years for cadastre projects.
Figure 5 shows the locations of the sites and an approximate trace of Tuzla and
Seferihisar faults (SFs). Stations are distributed both on the fault trace and some 20 km
away from the fault. The stations are close to each other along the south segment of
TF because the fault has a very complex and sectional structure in that area. This com-
plexity, named the Cumali segment, is a zone of several faults that are parallel to each
