Abstract
To evaluate the porosity profile within the Chelungpu Fault, which slipped during the 1999 Taiwan Chi-Chi Earthquake, we performed X-ray computed tomography imaging of core samples from Hole B of the Taiwan Chelungpu Fault Drilling Project. We established the relationship between the degree of X-ray attenuation and wet bulk density and obtained a porosity profile through the major fault zone at 1,136 m depth. The shear zones within the fault zone generally showed high porosity, and the porosity of the shear in the black gouge zone, which previous research suggests was the slip plane for the 1999 earthquake, was deduced to be 33.0%. This high porosity might indicate dilative shear deformation during the earthquake.
