Robert Shumway, professor of statistics at the University of California, Davis, has been studying how to detect nuclear tests since the 1960s. He can discuss how nuclear tests are detected, measured, and distinguished from earthquakes, mining explosions and other events. Detecting, locating and identifying large explosions is central to the Comprehensive Nuclear Test-Ban Treaty (CTBT), signed by the United States in 1996. Underground nuclear explosions generate patterns of seismic waves different from those created by earthquakes, while atmospheric tests generate low-frequency sound waves, or infrasound, that travel long distances through the air, as well as radioactive fission products that can be detected by air sampling. Underwater earthquakes and explosions, as well as some on land, generate hydroacoustic sound waves in the ocean. A worldwide network of sensors measures these events and sends the data to the International Data Center in Vienna, Austria. For example, scientists were able to monitor nuclear tests by India and Pakistan in 1998, showing that the explosions had lower yields than claimed. Shumway's research is supported by the U.S. Air Force Technical Applications Center through the Department of Defense. He recently co-edited a volume of the journal Pure and Applied Geophysics on the theme "Monitoring the Comprehensive Nuclear Test-Ban Treaty."