Figure 4 - Pore pressure change versus strain for natural sandy sediment from the Mallik 2L-38 well drilled in the Mackenzie Delta, NWT, Canada. Tests GH058, GH059, and GH060 did not contain gas hydrate at the time of shear, whereas GH062 did contain natural gas hydrate during the shear phase. All samples exhibit dilatant behavior as illustrated by the generation of negative (related to the beginning of shear) pore pressure. Contrast this behavior with the positive pore pressure response in Fig. 3C.