Scientists ready to have a blast near Cedarville

Published September 10, 2004
in the Klamath Falls Herald and News

By JEAN BILODEAUX

CEDARVILLE - Researchers from Stanford University will use a carefully timed set of explosions next week to study what scientists call the "extension paradox" that has been found in northern Nevada.

Scientists and graduate students from the university will set off six simultaneous explosions along a line stretching from north-central Nevada to the Modoc National Forest near Cedarville.

Seismic waves generated by the explosions will be recorded by more than 1,000 portable seismographs and geophones.

The extension paradox refers to variations in the thickness and structure of the earth's crust. As the crust is stretched it becomes thinner and, usually, lower in elevation. But that's not the case in some sections of northern Nevada. Scientists hope to find out why.

Stanford University obtained permits from the Bureau of Land Management's Surprise and Winnemucca field offices to set off the series of explosions.

The explosions, tentatively scheduled for next Wednesday or Thursday, will occur at night to reduce interference from background noise from other human activity in the region. Before the detonations, areas will be cleared for safety.

Visual and audio alarms will be used to signal the impending explosions. Noise from each shot will be a muffled thud sometimes accompanied by a sharp crack similar to a rifle shot. The shots may be heard up to a mile away.

Earth shaking from the detonations will not be felt beyond a few hundred feet.

Measurements of the time it takes for the waves from each location to reach the recording instruments will be used to create an accurate picture of the different rock types and structures present deep in the earth's crust.

Tests will use six boreholes drilled along a roughly east-west line in remote areas north of the Black Rock Desert in northwestern Nevada and into Modoc County's Surprise Valley.

All activities will be conducted in areas where the ground has already been disturbed, such as along roadways and within a gravel pit.

The recording devices will also be placed along existing roads. The data recorders will be retrieved following the detonations and the data transferred to a central computer.

All data gathered will be archived and publicly released through an Earthscope data center. Earthscope is a National Science Foundation program that is also providing the latest technology and equipment for the project.

Stanford will use the project to train a group of its undergraduate students in geologic and geophysical techniques required to study the continents. The goal of the project is to increase public appreciation of local geology and expand knowledge of the earth's crust to help scientists better understand the earthquake hazard in the region.

Correspondent Jean Bilodeaux covers Surprise Valley. She can be reached at (530) 279-2031, or at P.O. Box 5, Cedarville, CA 96104, or by sending an e-mail to jeanb@hdo.net