Accession Number : ADA264101


Title :   Attenuation and Source Studies in Northern Eurasia


Descriptive Note : Semi-annual rept. 9 Jul 92-8 Jan 93,


Corporate Author : SAINT LOUIS UNIV MO


Personal Author(s) : Xie, J K ; Mitchell, B J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a264101.pdf


Report Date : 28 Apr 1993


Pagination or Media Count : 34


Abstract : A non-linear method is developed for the simultaneous inversion of Lg source spectra and path Q. The method is applicable to both earthquakes and explosions. The unknowns are the source corner frequency and seismic moment, as well as Lg Q sub O and Ti values (Lg Q at 1 Hz and its power-law frequency dependence) along the paths to the recording stations. The inverse algorithm determines different Q sub O and n values for each of the several paths, it is event-based, and it is suitable for real-time processing. The algorithm is further characterized by an exhaustive, non-linear search for source parameters and linear searches for Q sub O and n values. The search process is implemented in successive, increasingly refined steps, designed to accelerate the computation. With these characteristics, the inverse algorithm requires neither a starting model, nor a priori information on the source and Q; it thus avoids convergence to local minima, and is fast enough to be mini-computer based. The method is applied to three underground nuclear explosions in eastern Kazakhstan. The resulting seismic moment (M sub O) and corner frequency (F sub c) for the largest (JVE) event are 1.3 (+ or - O.l) x 10(exp 23) dyne-cm and 0.56 (+ or - O.02) Hz, respectively. These values are consistent with previous estimates using other methods and phases, as well as the source scaling relationships developed for NTS explosions.


Descriptors :   *ALGORITHMS , *NUCLEAR EXPLOSIONS , *REAL TIME , *MODELS , FREQUENCY , PROCESSING , EXPLOSIONS , PHASE , TIME , UNDERGROUND , STARTING , EARTHQUAKES , VALUE , POWER , INVERSION , CONVERGENCE , SPECTRA , ESTIMATES , MOMENTS , PATHS , PARAMETERS , STATIONS , COMPUTERS , COMPUTATIONS


Subject Categories : Numerical Mathematics
      Computer Systems
      Test Facilities, Equipment and Methods
      Nuclear Explosions and Devices(non-military)


Distribution Statement : APPROVED FOR PUBLIC RELEASE