|Title||Analysis of earthquake body wave spectra for potency and magnitude values: implications for magnitude scaling relations|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Ross Z.E, Ben-Zion Y., White M.C, Vernon FL|
|Journal||Geophysical Journal International|
|Type of Article||Article|
|Keywords||attenuation; Body waves; coefficients; deep borehole recordings; depth; Earthquake source observations; fault; models; moment-magnitude; Seismicity and tectonics; seismograms; southern california; statistical seismology; stress|
We develop a simple methodology for reliable automated estimation of the low-frequency asymptote in seismic body wave spectra of small to moderate local earthquakes. The procedure corrects individual P- and S-wave spectra for propagation and site effects and estimates the seismic potency from a stacked spectrum. The method is applied to > 11 000 earthquakes with local magnitudes 0 < M-L < 4 that occurred in the Southern California plate-boundary region around the San Jacinto fault zone during 2013. Moment magnitude M-w values, derived from the spectra and the scaling relation of Hanks & Kanamori, follow a Gutenberg-Richter distribution with a larger b-value (1.22) from that associated with the M-L values (0.93) for the same earthquakes. The completeness magnitude for the M-w values is 1.6 while for M-L it is 1.0. The quantity (M-w - M-L) linearly increases in the analysed magnitude range as M-L decreases. An average earthquake with M-L = 0 in the study area has an M-w of about 0.9. The developed methodology and results have important implications for earthquake source studies and statistical seismology.