May 14, 2003 — UNIVERSITY OF UTAH NEWS ADVISORY

The news release below, about earthquake research by University of Utah hydrogeologist Craig Forster, was adapted from the American Geophysical Union’s AGU Journal Highlights dated May 13, 2003. Contact information and the dates of online and journal publication have been added.

Rock samples taken from a tunnel that runs through an active fault zone in Japan have provided evidence to indicate the structure and hydrogeology of the fault.

University of Utah hydrogeologist Craig Forster and colleagues examined rocks from boreholes deep within the Active Fault Survey Tunnel in Japan and used data from the fault’s fluid content to infer the permeability and porosity within the Mozumi-Sukenobu fault.

Such measurements, including a chlorofluorocarbon analysis to estimate the age of the water entering the tunnel through the zone’s porous rocks, can help researchers better understand the fault’s hydraulic structure and estimate the conditions leading up to an earthquake.

Their results support the hypothesis of a fluid-saturated fault zone model that contains an interlayered sequence of low-velocity porous and non-porous rocks that weakens seismic waves generated by earthquakes.

The study was printed in the journal Geophysical Research Letters, published by the American Geophysical Union.

Title: Hydrologic properties and structure of the Mozumi Fault, central Japan

Authors:
— Craig B. Forster, University of Utah, Salt Lake City, Utah
— James P. Evans and Ronald Jeffreys, Utah State University, Logan, Utah.
— Hidemi Tanaka, University of Tokyo, Tokyo, Japan.
— Tsuyoshi Nohara, Japan Nuclear Cycle Development Institute,
Jorinji, Izumi, Tokishi Gifu, Japan.

Publication dates: Geophysical Research Letters (GRL) online March 18, 2003 and in the yet-to-be issued print version that will be dated March 15, 2003.