Explosions detectionDifferentiating Earthquake from Underground Explosion

Published 9 August 2019

Sandia National Laboratories researchers, as part of a group of National Nuclear Security Administration scientists, have wrapped up years of field experiments to improve the United States’ ability to differentiate earthquakes from underground explosions, key knowledge needed to advance the nation’s monitoring and verification capabilities for detecting underground nuclear explosions.

Sandia National Laboratories researchers, as part of a group of National Nuclear Security Administration scientists, have wrapped up years of field experiments to improve the United States’ ability to differentiate earthquakes from underground explosions, key knowledge needed to advance the nation’s monitoring and verification capabilities for detecting underground nuclear explosions.

The nine-year project, the Source Physics Experiments, was a series of underground chemical high-explosive detonations at various yields and different depths to improve understanding of seismic activity around the globe. These NNSA-sponsored experiments were conducted by Sandia, Los Alamos National Laboratory and Lawrence Livermore National Laboratory and Mission Support and Test Services LLC, which manages operations at the Nevada National Security Site. The Defense Threat Reduction Agency, the University of Nevada, Reno, and several other laboratories and research organizations participated on various aspects of the program.

Researchers think recorded data and computer modeling from the experiments could make the world safer because underground explosives testing would not be mistaken for earthquakes. The results will be analyzed and made available to many institutions, said Sandia principal investigator and geophysicist Rob Abbott.

The dataset is massive. “It’s been called the finest explosion dataset of this type in the world,” Abbott said. “We put a lot of effort into doing this correctly.”

The final underground explosion in the series took place June 22.

Experiments Explored Differences Between Explosions in Hard, Soft Rock
Sandia Lab says that Phase 1 of SPE consisted of six underground tests in granite between 2010 and 2016. Phase 2 consisted of four underground tests in dry alluvium geology, or soft rock, in 2018 and 2019. The results from both phases will be analyzed to help determine how subsurface detonations in dry alluvium compare to those in hard rock. Additionally, the SPE data can be measured against data collected from historic underground nuclear tests that were conducted at the former Nevada Test Site.