Seismic attenuation parameters of seismic stations in the Korean Peninsula: Kappa and quality factor
Abstract
Kappa (κ) and quality factor (Q) are parameters describing attenuation of ground motions by characteristics of media in propagation path; Q indicates anelastic attenuation along whole propagation path, and κ means decay of high-frequency amplitude due to subsurface geological conditions. These parameters can be used to consider attenuation of ground motions in the stochastic ground-motion simulation . Accelerograms recorded at seismic stations administered by Korea Meteorological Administration and Korea Institute of Geoscience and Mineral Resources from 2003 to 2019 were used to estimate site-specific κ (κ0) and distance-dependency of κ (κR) of each station. Data were corrected for the and trend, and then the instrumental responses were deconvolved. We applied 5% Hanning taper at ends of them, and transferred to a spectrum using fast Fourier transform. We measured κ by dividing slope of decay in natural-log amplitude spectrum of an event at a station into -π. κ0 and κR of the station were estimated by linear regression of all κ values on hypocentral distances. The stochastic ground-motion simulation was performed using estimated κ0 for three earthquakes (MW 5.1, 5.5, and 4.4) occurred in Gyeongju in 2016. The simulated ground motions using site-specific κ0 apparently look closer to observed ground motions at the stations than a case using uniform κ0 value (0.023 sec) in the simulations. Some underestimated results are found in closer hypocentral distance. It might indicate that a set of path parameters used in the simulation is inappropriate to describe characteristics of attenuation for the Korean Peninsula. Meanwhile, Q can be estimated from relation between κR and Q. We checked and verified the attenuation models of Korea using the high-frequency decay parameter (κR).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMS002.0026A
- Keywords:
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- 7299 General or miscellaneous;
- SEISMOLOGY