SEISMOLOGYCOMPREHENSIVE TEST BAN TREATYBecause earthquake monitoring methods are also useful for monitoring massive explosions, seismic research may play an important role in preventing nuclear escalation and warfare. The Comprehensive Test Ban Treaty, drafted in 1996 and signed by many countries including the U.S. and Russia, implies that signatory nations, even as they await its ratification, will not undertake nuclear testing with devices corresponding to seismic magnitudes larger than about 3.0. Many nations are unwilling to sign or ratify the treaty unless there are methods to monitor small seismic events, at least in politically sensitive regions. Most current methods locate events by comparing the travel times of seismic phases arriving at several monitoring stations. Unfortunately, explosions with magnitudes as small as 3.0 are often recorded by only one or two stations and go unreported. To address this problem, UTIG scientists are currently developing methods that use seismic waveforms to more accurately locate earthquakes or explosions with data from a single broadband digital station. Whereas conventional seismic analysis focuses on phase arrivals only, this approach exploits the informational wealth of the entire waveform, against which the scientists attempt to match synthetic waveforms generated by sophisticated models. |