A global monitoring system for a nuclear test ban treaty

Abstract

The rolling text of Conference on Disarmament’s Nuclear Test Ban Treaty requires monitoring by 169 seismic, 11 hydroacoustic, 60 infrasonic, and 50 radionuclide stations. Stations will continuously transmit data to a center for real-time processing. Processing will detect, measure, and classify signals, then it will associate signals at different stations and locate sources. Results will be reviewed by analysis. To prepare, the Center for Monitoring Research participates in a seismic monitoring experiment, which is being broadened to other technologies. Continuous data from hydrophones at Point Sur and Wake Island have been received and processed at CMR since late 1995. Data from additional hydroacoustic stations are imminent. Software for processing seismic data will be adapted for hydroacoustics; real-time detection and feature measurement are underway. Visual review found signals from 30% of shallow, Pacific-region seismic sources in CMR’s bulletin, but the rate varied widely by source region. Among mb≳4.2, h<100 km earthquakes, detection was independent of magnitude and earthquake depth. Ocean depth near the epicenter may control hydroacoustic detection. Differences between visually selected onset times and times predicted from seismic locations and propagation modeling vary widely by region, and are often larger than differences predicted from seismic location uncertainty.