A new analysis of satellite data from the late 1990s documents for the first time the “uplift” of ground above a site of underground nuclear testing, providing researchers a potential new tool for analyzing the strength of detonation.
The study has just been published in Geophysical Research Letters.
Lead author Paul Vincent, a geophysicist at Oregon State University, cautions that the findings won’t lead to dramatic new ability to detect secret nuclear explosions because of the time lag between the test and the uplift signature, as well as geophysical requirements of the underlying terrain. However, he said, it does “provide another forensic tool for evaluation, especially for the potential explosive yield estimates.”
“In the past, satellites have been used to look at surface subsidence as a signal for nuclear testing,” said Vincent, an associate professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “This is the first time uplift of the ground has correlated to a nuclear test site. The conditions have to be just right and this won’t work in every location.
“But it is rather interesting,” he added. “It took four years for the source of the uplift signal – a thermal groundwater plume – to reach the surface.”
The focus of the study was Lop Nor, a nuclear testing site in China where three tests were conducted – May 21, 1992; May 15, 1995; and Aug. 17, 1995. Vincent and his colleagues analyzed interferometric synthetic aperture radar (InSAR) images from 1996-99 and detected a change in the surface beginning four years after the tests.
Though the uplift was less than two inches, it corresponds to known surface locations above past tests within the Lop Nor test site.
From past studies, the researchers knew that heat from underground detonation of nuclear devices propagates slowly toward the surface. At most sites – including the Nevada National Security Site – that heat signal dissipates laterally when it reaches the water table, which is usually deep beneath the surface.
At Lop Nor, however, the water table is only about three meters below the surface, and the heated groundwater plume took four years to reach that high, lifting the ground above the detonation site slightly – but enough to be detected through InSAR images.
Lop Nor also is characterized by a hard granite subsurface, which helps pipe the heated water vertically and prevents the subsidence frequently found at other testing sites.
A past study by Vincent, published in 2003, first shed light on how subsidence can manifest itself in different ways – from the force of the explosion creating a crater, to more subtle effects of “chimneying,” in which the blast opens up a chimney of sorts and draws material downward, creating a dimple at the ground surface.
Before joining the OSU faculty in 2007, Vincent spent several years as a physicist at the Lawrence Livermore National Laboratory.
Vincent said the analysis of nuclear explosions has become a specialized field. Seismology technology can provide an initial estimate of the energy of the explosion, but that data is only good if the seismic waves accurately reflect coupling to the connecting ground in a natural way, he explained. Efforts are sometimes made to “decouple” the explosive device from the ground by creating specializing testing chambers that can give off a false signal, potentially masking the true power of a test.
“Subsidence data combined with seismic data have helped narrow the margin of error in estimating the explosive yield,” Vincent noted, “and now there is the potential to use test-related thermal expansion as another forensic tool.”
Co-authors on the paper with Vincent include Sean Buckley of the Jet Propulsion Laboratory, Dochul Yang, the University of Texas-Austin, and Steve Carle, of Lawrence Livermore National Laboratory.
About the OSU College of Oceanic and Atmospheric Sciences: COAS is internationally recognized for its faculty, research and facilities, including state-of-the-art computing infrastructure to support real-time ocean/atmosphere observation and prediction. The college is a leader in the study of the Earth as an integrated system, providing scientific understanding to address complex environmental challenges.
Paul Vincent | EurekAlert!
Algorithm provides early warning system for tracking groundwater contamination
14.08.2018 | DOE/Lawrence Berkeley National Laboratory
Artificial Glaciers in Response to Climate Change?
10.08.2018 | Universität Heidelberg
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
14.08.2018 | Information Technology
14.08.2018 | Life Sciences
14.08.2018 | Life Sciences