Low Frequency Electro Magnetic Signatures for Detecting&Discriminating Nuclear/non-nuclear Underground Tests

ISL in Phase 1 will calculate electromagnetic source signatures for both nuclear and non-nuclear underground tests (UGTs). We will also establish methods and computer algorithms for calculating the electromagnetic pulse (EMP) caused by the detonation, at any receiver location, as it propagates through varied subsurface geology. We currently have in-house code for calculating dipolar E and B sources, for layered media, and we also have access to 3D calculation code via the CEMI consortium. We plan to apply these codes, which are for harmonic sources, to the problem of EMP calculation via Fourier decomposition and re-combination. In Phase 1 we will validate these codes for this procedure, and will then use them to create a realistic geologic test-bed for nuclear EMP propagation. We will use this test-bed to determine the accuracy, reliability, and stability of the propagation algorithm, for a range of complex earth geometries, including land-ocean interfaces. We will also calibrate and test the sources and pulse propagation by modeling known historical events and comparing the output to known observations, and identify candidate signal processing algorithms for detection, estimation, and discrimination of features of UGT-generated EMP signals. The goal is to work towards an eventual library of signatures.