Earthquake source scaling relationships from -1 to 5 ML using seismograms record at 2.5-km depth
Lin, Yen-Yu
Abstract
The three important parameters, seismic moment(M0), corner frequency(fc) and t* value are estimated from seismogram. After investigating them, we can estimate magnitude, fault radius and attenuation value of the earthquake. The scaling relationships of earthquake sources less then about magnitude 3 have been the subject of considerable controversy over the last two decades. Studies of such events have shown a tendency for the constant stress drop, self similarity of larger earthquakes to breakdown at small magnitudes, and an apparent minimum source dimension of about 100m has been observed. Source parameters are calculated by Brune ω-2 (n=2) model. In model 1, n=2 is fixed, and Q of P and S waves is determined to be 912 and 1078, respectively. In model 2, Qp=Qs=1000 is assumed and n is allowed to vary. In model 3, Qp=Qs=1000 is also assumed and ω-2 is constrained, and in model 4, attenuation is ignored and n is allowed to vary. The radio between radiated seismic energy and seismic moment appears to decrease gradually with decreasing moment in the magnitude range -1 to 7. This is not incompatible with a constant stress drop but could result form errors in calculating energy. To collect lots of data, seismic energy is distributed across a wide frequency band.
Reference
Abercrombie, R. E., Earthquake source scaling relationships from -1 to 5 ML using seismograms recorded at 2.5-km depth, J. Geophys. Res., 100, 24015-24036, 1995.
(Abstract) (Full text)
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