These latest results, according to Barker et al., indicate “high confidence” that the network being set up to monitor the CTBT can indeed verify small nuclear explosions. Concerns over the effectiveness of the monitoring network have made it extremely difficult for supporters of the treaty to have it ratified by the US congress. Only two of the five ‘official’ nuclear states – France and the UK- and 19 other countries have ratified the CTBT^*. Another 129 countries have signed but have yet to ratify the treaty.

When it is completed, the monitoring network will consist of 321 stations that will be capable of registering shock waves emanating from a nuclear explosion underground, in the sea or in the air, as well as detecting the radioactive particles released into the atmosphere. Only 61% of the seismic stations were operational at the time of the Indian and Pakistani tests. However, Barker et al. point out that the system automatically recognised the nuclear explosions on May 11, 28 and 30 among a total of 70000 seismic events. Later refinements of the data enabled them to produce a map pinpointing the locations of the explosions to within 10 km.

As the network was unable to detect India’s sub-kiloton tests on May 13, the scientists suggest that the explosions must have been 500 times smaller than the estimated 16 kiloton event on May 11. Such small explosions are unlikely to be nuclear denotations. And although the monitoring stations did not pick up two explosions on May 11, the fact that the seismic data clearly demonstrated a nuclear denotation signal shows, according to Barker et al., that the CTBT monitoring network was “remarkably successful”

*The 21 States that have ratified the Treaty are: Australia, Austria, Brazil, Czech Republic, El Salvador, Fiji, France, Germany, Grenada, Japan, Jordan, Micronesia (Federated States of), Mongolia, Peru, Qatar, Slovakia, Spain, Tajikistan, Turkmenistan, United Kingdom, and Uzbekistan.