Seismic Science and Nonproliferation
WHEN it comes to the nation’s nuclear security, Lawrence Livermore is best known for its responsibilities for the U.S. nuclear arsenal. But since the 1960s, Livermore scientists have also supported the efforts of U.S. policy makers to contain the nuclear arms race and limit nuclear proliferation by developing the means to verify disarmament and nonproliferation treaties. Today, Livermore and other Department of Energy national laboratories continue to press ahead with research on many fronts that enhance U.S. capabilities to monitor and limit proliferation.
For example, as the article Sleuthing Seismic Signals describes, Livermore is addressing the challenge of identifying and locating small nuclear explosions through seismic monitoring. In fact, one Laboratory mission is to better predict seismic signals and improve our ability to distinguish nuclear tests in the continuous stream of signals emitted by Earth’s ongoing tectonic activity, such as earthquakes and volcanoes, as well as the occasional man-made event. The seismic signature that results from a nuclear test differs from that of an earthquake or other natural event, but Earth alters the signal in ways that can be challenging to decipher.
A small, low-yield nuclear test can be particularly difficult to pick out from other seismic activity. North Korea’s small nuclear test in 2006 offered data that Livermore experts have since incorporated in new simulation tools with the potential to vastly improve the ability to quickly and accurately distinguish a small nuclear event and pinpoint its location. Three-dimensional models of Earth’s interior, tomographic analysis techniques, and applications that run on high-performance computing assets such as BlueGene/L will continue to play key roles in developing improved methodologies to detect and characterize nuclear events.
We are entering a new era in nuclear test monitoring capability, as signs appear that U.S. nonproliferation policy may rely more heavily on the Comprehensive Nuclear Test Ban Treaty. Since the treaty was open for signature in 1996, 180 states have signed it, and 148 states have ratified it. However, it will only go into force after all 44 nuclear-capable states have ratified it. Nine such countries, including the U.S., have yet to do so. President Barack Obama has promised to encourage the U.S. Senate to ratify the treaty and to work through diplomatic efforts to bring other nuclear-capable states on board. A decision about ratification may well depend on the nation’s ability to verify compliance through seismic monitoring.