Some Aspects of the Seismic Scaling and the Strong Ground Motion of the Eastern Missouri Earthquake of January 12, 1984

Strong-motion records from a velocity meter were recorded at an epicentral distance of 4.5 km from the January 12, 1984 eastern Missouri earthquake of m_b = 3.0. Peak values of ground velocity, associated with only one or two wave cycles, are: transverse component, 0.18 cm/sec; radial component, 0.16 cm/sec; vertical component, 0.12 cm/sec. The levels of the sustained motion, which extends from the onset of S to about 0.4 sec later, are: transverse component, 0.064 cm/sec; radial component, 0.061 cm/sec; vertical component, 0.061 cm/sec. The data are consistent with a spectral scaling relation assuming either a 3.5 or 4.0 slope of the logarithm of the seismic moment versus the logarithm of the corner frequency, but cannot be used to choose between the two relations.