Attenuation of High-Frequency P and S Waves in the Crust of Choongchung Provinces, Central South Korea

Recently Choongchung provinces in central South Korea have received increasing attention because a new administrative capital will be constructed there. In this area, we installed the seismic network of the Korea National University of Education in December 1997. We have analyzed Qp^-1 and Qs^-1 by the extended coda normalization method based on 114 events recorded by the four stations of the network. To compensate for insufficient data, we added data from 94 events observed by two stations of the network of the Korea Institute of Geoscience and Mineral Resources. Estimates of Qp^-1 and Qs^-1 are frequency dependent and decrease from (3.6 (plusminus) 4.2) x 10^-3 and (2.2 (plus-minus) 4.4) x 10-3 at 1.5 Hz to (6.3 (plus-minus) 0.1) x 10^-4 and (6.5 (plus-minus) 0.1) x 10^-4 at 24 Hz, respectively. If we fit a frequency-dependent power law to the data, the best fits for Qp^-1 and Qs^-1 are (3.0 (plus-minus) 0.1) x 10-3f -0.54(plus-minus)0.01 and (3.0 (plus-minus) 0.1) x 10^-3f^ -0.42(plus-minus)0.02, respectively. These values correspond to those of seismically stable regions and are slightly less dependent on frequency than those of southeastern Korea, due to high Q-1 values at high frequency. Further observations are required in central South Korea to evaluate the difference of Q-1 between central and southeastern South Korea.