CTBT seismic monitoring using coherent and incoherent array processing

Abstract The detection and location capability of the International Monitoring System for small seismic events in continental oceanic regions surrounding Sea Japan is determined mainly by three primary arrays: USRK, KSRS, MJAR. Body wave arrivals are coherent on USRK KSRS up to frequencies around 4 Hz classical array processing methods can detect extract features most regional signals these stations. We demonstrate how empirical matched field (EMFP), a generalization frequency-wavenumber or f-k analysis, contribute calibrated direction estimates which mitigate bias resulting from near-station geological structure. It does this comparing narrowband phase shifts between different sensors, observed at given time, with corresponding measurements historical events. EMFP statistic usually evaluated as function source rather than slowness space size geographical footprint valid templates affected geometry, available signal bandwidth, Earth structure over propagation path. MJAR arrayhas similar dimensions but sited far more complex geology results poor parameter analysis all lacking energy 1 below. mitigates incoherence some degree template very small. Spectrogram beamforming provides robust algorithm high-frequency aperture large enough that performed continuous AR-AIC functions, calculated optimally bandpass-filtered sites, provide P-waves. Given significantly higher SNR S-phases horizontal components 3-component site MJAR, we would expect incoherent estimation improve sensors sites. diversity IMS stations, optimal station, advocate development pipelines process highly heterogeneous inputs help associate characteristics incoming physical