The Comprehensive Test Ban Treaty

The Comprehensive Test Ban Treaty (CTBT) was signed on September 24, 1996 by President Clinton and other world leaders in an effort to end nuclear testing. With the CTBT and the means to enforce it in place nuclear weapons testing will, at least theoretically, be a thing of the past. The first legislation of this type was passed in 1974 as the Threshold Test Ban Treaty,this treaty had no provisions for the exchange of seismic calibration data and fell short of its goals. The CTBT, however, calls for a complete end to testing and is backed up by seismic and hydroacoustic monitoring and on-site test inspections.

Nuclear testing with the seismometer

Nuclear explosions send out seismic vibrations that can be recorded by seismometers. This is one of the primary ways nuclear weapon testing can be monitored. The explosions are always shallow in the earth's crust and have relatively low magnitudes.

The Global Seismic Network, which consists of 50 primary and 120 auxiliary seismic stations, serves as the mainstay of the CTBT International Monitoring System (IMS). This system requires a detection threshold of magnitude 4.25 and hopes to pinpoint possible nuclear seismic occurrences to within 1000 km2.

The United States National Data Center (NDC), through the U.S. Department of Energy, has recieved research funding to monitor nuclear events. Using both natural and man-made events, the NDC is compiling data for several regions of the world to distinguish between natural and nuclear seismic disturbances. Western China and the Middle East/North Africa regions are the main areas on which the NDC has been focusing. By pinpointing fairly small regions, the NDC hopes to create a full range of helpful data based on the region's geological, geophysical, cultural, and meteorological characteristics. Using the data compiled for these two regions, the NDC hopes to gather enough information to create algorithms which will aid in detecting, pinpointing locations, estimating the depth, identifying, and characterizing the different types of seismic events. The information gathered will also aid in creating physical models for which the IMS can follow when determining whether a seismic event was natural or the result of a nuclear weapons test.

For more information regarding nuclear testing and seismic recordings of nuclear tests please consult: