Hydrologic Properties and Structure of the Mozumi Fault, Central Japan

Authors

Craig B. Forster, University of Utah
James P. Evans, Utah State UniversityFollow
Hidemi Tanaka, University of Tokyo
Ronald Jeffreys, Utah State University
Tsuyoshi Nohara

Document Type

Article

Journal/Book Title/Conference

Geophysical Research Letters

Volume

30

Issue

6

Publisher

American Geophysical Union

Publication Date

2003

First Page

8010

Abstract

Analyses of rocks from the Active Fault Survey Tunnel (AFST) provides insight into the structure and hydrogeology of the northeast-trending Mozumi-Sukenobu fault, an active strike-slip fault with 125 to 500 m of right-lateral slip in central Japan. Interlayered regions of sub-vertical permeability zones formed by cataclasis and slip on clay-rich foliated zones. Core samples range from 10⁻¹⁹ m² to almost 10⁻¹³ m². CFC analyses of waters from the fault zone show that water entering the tunnel is 27–36 years old, yielding a bulk fault permeability of 10⁻¹⁴ to 10⁻¹⁵ m². The data support a fault zone model of a fluid-saturated, low-velocity zone with a sharp velocity contrasting with the protolith. Pore-fluid pressures could build and dissipate in isolated high permeability pods 10's–100's m in dimension.

Comments

Originally published by American Geophysical Union. Publisher's PDF available through Geophysical Research Letters.

Recommended Citation

Forster, C. B., Evans, J. P., Tanaka, H., Wantanabe, K., Jeffreys, R., and Nohara, T., 2003, Near-surface hydrologic structure of an Active Fault: The Mozumi Fault, Japan, Geophysical Research Letters. 30 (6), 8010, doi:10.1029/2002GL014904.