HR: 15:10h
AN: S53C-07    [Abstracts]
TI: A New P-wave Frequency Dependent Magnitude Estimation Technique
AU: * Veith, K F
EM: karl.veith@itt.com
AF: ITT Industries - AES, 2560 Huntington Avenue, Alexandria, VA 22303 United States
AU: Rivers, W
EM: wilmer@multimax.com
AF: Multimax, Inc., 1441 McCormick Drive, Largo, MD 20774 United States
AU: Wagner, R
EM: wagner@multimax.com
AF: Multimax, Inc., 1441 McCormick Drive, Largo, MD 20774 United States
AB: A new procedure for estimating Mb is suggested which is analogous to the new procedure being proposed by Russell and Bonner (2005) for the estimation of surface wave magnitudes. The measurement process involves the use of narrow pass band Butterworth filters on broad band station data that isolate the amplitude of the P waves at each particular frequency. The amplitude-period data are then used to estimate magnitudes with corrections for both the filtering process and frequency dependent attenuation. The magnitudes generally vary smoothly with frequency and the maximum value is selected for each station's Mb. The technique offers a number of advantages over tradition Mb measurement procedures. These include an inherently increasing window length with increasing period. This allows the technique to utilize longer period data for large events. In selecting the maximum Mb from the frequency-magnitude data the effects of the corner frequency on the event magnitude are also avoided. New work by Veith (2005) defines both the frequency dependent attenuation for P waves and an improved worldwide regional magnitude correction curve. While the need for region specific correction curves is evident, the worldwide average curve together with the frequency dependent attenuation corrections offers significantly improved regional Mb estimates, particularly when combined with this new analysis technique.
DE: 7200 SEISMOLOGY
DE: 7203 Body waves
DE: 7215 Earthquake source observations (1240)
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005