DOI QR코드

DOI QR Code

근거리 지진관측자료의 S파를 이용한 지진규모 평가 연구

A Study on Estimating Earthquake Magnitudes Based on the Observed S-Wave Seismograms at the Near-Source Region

  • 연관희 (한전전력연구원 구조건설연구실) ;
  • 최신규 (한전전력연구원 구조건설연구실) ;
  • 이강렬 (한전전력연구원 구조건설연구실)
  • Yun, Kwan-Hee (Structural & Construction Tech. Group, Korea Electric Power Corporation (KEPCO) Research Institute) ;
  • Choi, Shin-Kyu (Structural & Construction Tech. Group, KEPCO Research Institute) ;
  • Lee, Kang-Ryel (Structural & Construction Tech. Group, KEPCO Research Institute)
  • 투고 : 2023.12.21
  • 심사 : 2024.01.23
  • 발행 : 2024.05.01

초록

There are growing concerns that the recently implemented Earthquake Early Warning service is overestimating the rapidly provided earthquake magnitudes (M). As a result, the predicted damages unnecessarily activate earthquake protection systems for critical facilities and lifeline infrastructures that are far away. This study is conducted to improve the estimation accuracy of M by incorporating the observed S-wave seismograms in the near source region after removing the site effects of the seismograms in real time by filtering in the time domain. The ensemble of horizontal S-wave spectra from at least five seismograms without site effects is calculated and normalized to a hypocentric target distance (21.54 km) by using the distance attenuation model of Q(f)=348f0.52 and a cross-over distance of 50 km. The natural logarithmic mean of the S-wave ensemble spectra is then fitted to Brune's source spectrum to obtain the best estimates for M and stress drop (SD) with the fitting weight of 1/standard deviation. The proposed methodology was tested on the 18 recent inland earthquakes in South Korea, and the condition of at least five records for the near-source region is sufficiently fulfilled at an epicentral distance of 30 km. The natural logarithmic standard deviation of the observed S-wave spectra of the ensemble was calculated to be 0.53 using records near the source for 1~10 Hz, compared to 0.42 using whole records. The result shows that the root-mean-square error of M and ln(SD) is approximately 0.17 and 0.6, respectively. This accuracy can provide a confidence interval of 0.4~2.3 of Peak Ground Acceleration values in the distant range.

키워드

과제정보

본 논문은 한전 전력연구원의 『변전소 지진관측정보 자동 품질평가 기술개발(R22SA03)』 연구 일환으로 수행되었음.

참고문헌

  1. Korea Meteorological Administration. Documentation for the second half of year 2023 Earthquake․ Tsunami and Volcanic activity Council of Observation Agencies; c2023. 59 p. (in Korean).
  2. NECIS (National Earthquake Comprehensive Information System) of Korea Meteorological Administration [Internet]. [cited 2024 Apr] Available from: https://necis.kma.go.kr.
  3. Cho CS. Personal Communication; c2023.
  4. Atkinson GM, Hanks TC. A high-frequency magnitude scale. Bull Seismol Soc Am. 1995 Jun;85(3):825-833. https://doi.org/10.1785/BSSA0850030825
  5. Hanks TC, Kanamori H. A moment magnitude scale. J Geophys Res. 1979 May;84(B5):2348-2350. https://doi.org/10.1029/JB084iB05p02348
  6. Boore DM. Simulation of ground motion using the stochastic method. Pure Appl Geophys. 2003 Mar;160:635-676. https://doi.org/10.1007/PL00012553
  7. Lior I, Ziv A. The relation between ground motion, earthquake source parameters and attenuation: Implications for source parameter inversion and ground motion prediction equations. J Geophys Res. 2018 Jul;123(7):5886-5901. https://doi.org/10.1029/2018JB015504
  8. Lior I, Ziv A. Generic source parameter determination and ground-Motion prediction for earthquake early warning. Bull Seismol Soc Am. 2020 Jan;110(1):345-356. https://doi.org/10.1785/0120190140
  9. Yun KH, Park DH. Method of estimating the Ground-Motion Intensity Measures at a nearby site by using the Time-domain Transformation of Site Response. Korean Society of Earth and Exploration Geophysicists. 2010 Aug;13(2):219-226 (in Korean).
  10. Yun KH. Two-dimensional Q tomography inversion for the southern part of the Korean Peninsula. Ph. D. Dissertation. Seoul National University; c2007 (in Korean).
  11. Yun KH, Silva W, Park DH, Chang CJ. Inversion of stochastic earthquake model parameters using the modified Levenberg-Marquardt's method in Korea. Proceedings of EESK Conference. 2002 Mar 1; Seoul; c2002. p. 20-27 (in Korean).
  12. Brune JN. Tectonic stress and the spectra of seismic shear waves from earthquakes. J Geophys Res. 1970 Sep;75(26):4997-5009. https://doi.org/10.1029/JB075i026p04997
  13. Brune JN. Correction. J Geophys Res. 1971 Jul;76(20):5002.