Affiliation:
1. 1Department of Geophysics, Stanford University, Stanford, California, U.S.A.
Abstract
ABSTRACTWe determine the seismic moment and corner frequency of earthquakes using narrowband, time-domain measurements of the maximum shear-wave displacement amplitude. Each S wave is passed through a set of one-octave band-pass filters between 0.25 and 32 Hz to measure the peak amplitude on the horizontal components. Following the development of Richter (1935) local magnitude scale, we derive a functional form of maximum amplitude versus distance, but separately for each frequency band, and use them to estimate wave attenuation as a function of frequency and distance. Attenuation is a strong function of frequency, approximately proportional to 1/f, with path averaged Q increasing (attenuation decreasing) with propagation distance. We use these empirical attenuation curves to correct the time-domain peak amplitudes to a reference distance of 10 km to recover the source spectrum. We find that the spectral shape is consistent with the Brune model, showing a well-defined plateau at low frequency and a decay at high frequency proportional to ω−2. We use the median spectrum for stations at distances up to 120 km for each event to measure the moment and corner frequency. This time-domain method provides a reliable and efficient way to accurately measure earthquake source parameters.
Publisher
Seismological Society of America (SSA)
Subject
Geochemistry and Petrology,Geophysics
Reference31 articles.
1. Scaling law of seismic spectrum;Aki;J. Geophys. Res.,1967
2. Empirical and synthetic approaches to the calibration of the local magnitude scale, ML, in southern Kansas;Al-Ismail;Bull. Seismol. Soc. Am.,2020
3. Local magnitudes, seismic moments, and coda durations for earthquakes near Oroville, California;Bakun;Bull. Seismol. Soc. Am.,1977
4. A spectral theory for circular seismic sources; simple estimates of source dimension, dynamic stress drop, and radiated seismic energy;Boatwright;Bull. Seismol. Soc. Am.,1980
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