GEOPHYSICAL RESEARCH, 2018, vol. 19, no. 1, pp. 30-48. https://doi.org/10.21455/gr2018.1-3

UDC 550.347.097

Abstract  References   Full text (in Russian)

STATION CORRECTIONS FOR THE KNET SEISMOLOGICAL NETWORK ESTIMATED FROM H/V SPECTRAL RATIO OF SEISMIC NOISE AND LOCAL EARTHQUAKES

N.A. Sycheva, A.N. Mansurov

Research Station RAS in Bishkek city, Kyrgyzstan

Abstract. Station corrections are computed for ten stations of KNET seismological network to consider site effects due to a thin low-density layer underneath the stations. This layer may amplify seismic signal at certain frequencies and cause resonance effects. Station corrections are obtained on the basis of H/V spectral ratio calculations. S-wave records of 90 local earthquakes and 5000 of 60-second fragments of ambient seismic noise were analyzed. We compared site amplifications estimated from ambient noise and earthquakes; generally they are consistent. At certain segments within the considered frequencies from 1 to 20 Hz, some differences are observed in shape of corrections depended on frequency; the amplitude range of site amplification differs at AAK, AML, and KZA stations. Strong resonance features are absent at all stations in the frequency range considered. Stations AAK, AML, KBK, and TKM2 display significant resonance features at certain frequencies, whereas at stations CHM, EKS, KZA, UCH, ULHL, and USP, site amplification is close to unity and can be neglected. The values of site amplification can be utilized in computation of source spectra of earthquakes.

Keywords: site effect, site amplification, resonance, seismic station, seismogram, spectrum, seismic noise, earthquake.

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