Accession Number : ADA516371


Title :   Advanced Waveform Simulation for Seismic Monitoring


Descriptive Note : Conference paper


Corporate Author : CALIFORNIA INST OF TECH PASADENA


Personal Author(s) : Helmberger, Donald V ; Rodgers, Arthur J ; Ni, Sidao ; Wei, Shengji ; Tromp, Jeroen


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a516371.pdf


Report Date : Sep 2008


Pagination or Media Count : 12


Abstract : Earthquake source parameters underpin several aspects of nuclear explosion monitoring. Such aspects are: calibration of moment magnitudes (including coda magnitudes) and magnitude and distance amplitude corrections (MDAC); source depths; discrimination by isotropic moment tensor components; and waveform modeling for structure (including waveform tomography). This project seeks to improve methods for and broaden the applicability of estimating source parameters from broadband waveforms using the Cut-and-Paste (CAP) methodology. The CAP method uses a library of Green's functions for a one-dimensional (1D, depth-varying) seismic velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and radial components) and Love (transverse component). Source parameters are estimated by grid search over strike, dip, rake and depth and seismic moment or equivalently moment magnitude, MW, are adjusted to fit the amplitudes. Key to the CAP method is allowing the synthetic seismograms to shift in time relative to the data in order to account for path-propagation errors (delays) in the 1D seismic velocity model used to compute the Green's functions. The CAP method has been shown to improve estimates of source parameters, especially when delay and amplitude biases are calibrated using high signal-to-noise data from moderate earthquakes, CAP+.


Descriptors :   *NUCLEAR EXPLOSIONS , *SIMULATION , *SEISMIC WAVES , *WAVEFORMS , PARAMETERS , SIGNAL TO NOISE RATIO , GREENS FUNCTIONS , MOMENTS , AMPLITUDE , CALIBRATION , CORRECTIONS , GROUND BASED , EARTHQUAKES , RANGE(DISTANCE) , MONITORING , SYMPOSIA , TOMOGRAPHY


Subject Categories : Seismology
      Radiofrequency Wave Propagation


Distribution Statement : APPROVED FOR PUBLIC RELEASE