A Study of response Spectrums and characteristics of Time-Frequency Domain of Microearthquakes in the Central Part of South Korea

남한 중부지역 미소지진들의 응답 스펙트럼 및 시간-주파수 영역에서의 특성에 관한 연구

The microearthquake and explosion events recorded in the seismic KNUE(Korea National University of Education) network were analyzed. The seismic data were recorded from Dec. 1997 to Dec. 1998. Total of 118 records consisted of 24 earthquake and 4 explosion events were instrumented at 6 stations. Spectral values increases as magnitude increases and the predominant frequency band expands to low frequency. zone as magnitude increases. Three-dimensional spectrograms(time frequency. amplitude) were also synthesized in order to discriminate microearthquakes and artificial underground explosions. The waves from microearthquakes show that frequency content of dominant amplitude appeared above 10 Hz and the discrimination can be performed in almost all the frequency domain of 3-d spectrogram.