given element in two dimensions. The right hand side terms account for changes in
storage of fluid mass due to change in hydraulic head and addition or removal of fluid or
pressure. When initial conditions, boundary conditions and the controlling hydrologic
parameters are known, Equation (1) can be solved for head at any point in a two-
dimensional field at any given time. The equations present here are changes made to
those in Chapter 3. For a complete explanation of the model equations refer to the
"Model Equations" in chapter 3.
Model Dimensions, Boundary Conditions, and Initial Conditions
The cross-section model consists of four zones: the upper hemipelagics that form
the wedge, the decollement, the turbidites and the underthrust hemipelagic sequence
(Figure 4-2). The properties for the four hydrogeologic units were assigned based on
geological observations and laboratory measurements. The model domain was
discretized into finite element grid consisting 8100 nodes and 7920 quadrilateral elements
(Figure 4-2). Horizontally the model extends to a maximum of 50 km arcward of the
deformation front during the total simulation time. Vertically the model extends from the
seafloor to a maximum depth of 3 km at full growth. At the deformation front the
incoming sediment sequence was divided into 470 m of underthrust sediments, 15 m of
decollement zone and 173 m of accreted sediments. Values of no (0.7) and b (8 x 10-4 m
1) for hemipelagic sediments were obtained from Screaton and Ge (1997) while for
turbidites (no=0.6, b = 7 x 10-4 m-1), the porosity-depth relationship of Bekins and Dreiss
(1992) was used. The no and b values used for turbidites were similar to those values
used by Screaton and Ge (1997) for Barbados sediments south of Tiburon Rise, as these
sediments are rich in turbidites.