is so low that only a very small amount of water needs to escape to drastically to lower

the pore pressure (Byerlee, 1990). However, it is difficult to confirm flow in the arcward

direction based on the results of this study.

 The results of the base run has k* values lower than the results of Bekins et al.

(1995) by 0.1 at the deformation front, while having k* values 0.2-0.3 higher 50 km

arcward from the deformation front. These differences are caused by the different

parameters (permeability-porosity relationships in the decollement and turbidite unit)

used in the two simulations.

 The k* values of the base run provides the upper limit values of k* within the

decollement and the underthrust sediments because the sediments in the decollement and

underthrust would not lose fluid to the prism sediments above. Based on the estimated k*

values from the base run, the k* values does not reach lithostatic during 2.7 million years

of prism growth, and thus does not meet the criteria for horizontal hydrofracture in the

decollement (k* = 1). However, it should be noted that it may be possible that at greater

depths, addition of pressure due to smectite dehydration might be important, and may

even increase pore pressures above lithostatic.

 Based on the results of the base run it was not possible to reach lithostatic pore

pressures resulting in horizontal hydrofracture in the decollement. However, according

to the criteria given by Behrmann (1991), the X* values needed for vertical hydrofracture

is less than 1. Furthermore, vertical focusing of flow has been observed by 3-D seismic

images, which shows normal faults extending upward within the turbidite unit (Zhao and

Moore, 1998). If vertical hydrofracture could increase pore pressures in the decollement

then it is possible for the pressures in the decollement to reach lithostatic. To simulate