- Volume 17 Issue 3
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Discrimination between Earthquakes and Explosions Recorded by the KSRS Seismic Array in Wonju, Korea
원주 KSRS 지진 관측망에 기록된 지진과 폭발 식별 연구
- Jeong, Seong Ju (Earthquake Research Center, Geological Research Division, Korea Institute of Geoscience and Mineral Resources) ;
- Che, Il-Young (Earthquake Research Center, Geological Research Division, Korea Institute of Geoscience and Mineral Resources) ;
- Kang, Tae-Seob (Department of Earth and Environmental Sciences, Pukyong National University)
- Received : 2014.06.23
- Accepted : 2014.07.24
- Published : 2014.08.31
This study presents a procedure for discrimination of artificial events from earthquakes occurred in and around the Korean Peninsula using data set in the Wonju KSRS seismograph network, Korea. Two training sets representing natural and artificial earthquakes were constructed with 150 and 56 events, respectively, with high signal to noise ratio. A frequency band, Pg(4-6 Hz)/Lg(5-7 Hz), which is optimal for the discrimination of seismic sources was derived from the two-dimensional grid of Pg/Lg spectral amplitude ratio. The corrections for the effects of earthquake magnitude and hypocentral distance were carried out for improvement of discrimination capability. For correcting the effect of magnitude dependence due to the inverse proportionality of corner frequency to seismic moment, the Brune's source spectrum was subtracted from the observation spectrum. The spectrum was corrected using the optimal damping coefficient to remove damping effect with the hypocentral distance. The effect of locally varying spectrum ratio was cancelled correcting variation of wave propagation along the ray path. The performance in discrimination between training sets of natural and artificial events was compared using the Mahalanobis distance in each step of correction. The procedure of magnitude, distance, and path corrections show clear improvements of the discrimination results with increasing Mahalanobis distance, from 1.98 to 3.01, between two training sets.
Supported by : 한국지질자원연구원
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