Date of Completion
nuclear discrimination, statistical seismic scattering, crustal seismic attenuation
Dr. Vernon Cormier
Dr. Lanbo Liu
Dr. Timothy Byrnes
Field of Study
Doctor of Philosophy
Monitoring the Comprehensive Nuclear Test Ban Treaty requires analysts to discriminate seismic signals generated by earthquakes vs nuclear explosions. Seismologists are generally able to discriminate large energy events (> 5 mb) at teleseismic distances (greater than about 1,000 km). However, lower energy events need to be analyzed at regional distances because the energy attenuates with distance. At regional distances (< 1,000 km), the seismic energy travels primarily through the Earth’s crust and can be affected by large- and small-scale crustal structures. This can have the effect of making earthquakes look more like explosions and vice versa and is very dependent on the region through which the energy travels. Therefore new methods are needed to assist in the discrimination of events recorded at regional distances.
The work discussed here uses a new computer code to model the combined effects of known 3-D relatively large (deterministic) Earth structures and relatively small (statistical) structures to generate improved structural models and evaluate the performance of yield estimators and discriminants at selected seismic stations in Eurasia. This is accomplished by synthesizing seismograms using a radiative transport technique to predict the high frequency coda (>2-5 Hz) of regional seismic phases at stations having known relatively large, three-dimensional structure, combined with experiments to estimate the effects of multiple-scattering from unknown smaller structures.
Fitzpatrick, Michele, "Discrimination of Problem Seismic Events by Modeling the Combined Effects of Deterministic and Statistical Structure on Regional Seismograms" (2015). Doctoral Dissertations. 758.