NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.
Support for this study was provided by Award No. DE-AF01-97NN20001 between the National Academy of Sciences and the Department of Energy’s Office of Non-Proliferation and National Security.
Copies of this report are available from
Board on Earth Sciences and Resources
National Research Council
National Academy of Sciences
2101 Constitution Avenue, NW
Washington, DC 20418
Cover: Video image taken 6.300 seconds into a large cast shot at the Black Thunder coal mine in Wyoming. Superimposed on the image are traces of the radial (R), transverse (T), and vertical (Z) velocities recorded 5 km from the blast. The vertical bar at the right side of the traces is at 6.3 seconds after the beginning of the shot. The three-component particle velocity is represented in the lower right-hand corner. Figure courtesy of Brian Stump and David Anderson, both at Southern Methodist University, Dallas, Texas.
Copyright 1998 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America