Abstract
A seismic coda wave from local earthquakes is an indication of heterogeneity in the crust and upper mantle, and codaQ (Q c ) is the parameter defining the temporal decay of the coda wave. ButQ c estimates obtained with the conventional least-square method are not based on any solid statistical background, assuming the Gaussian distributiona priori. In this study, we propose a statistically reliable estimation method of estimatingQ c using the maximum likelihood method, and show its validity and usefulness with the data from the 1986 Joint Seismological Research in the western Nagano Prefecture. We found first that theQ c estimation with the maximum likelihood method is statistically valid and its reliability can be checked with the χ-square test. Next,Q c around Ohtaki village, within the studied area, is estimated using the maximum likelihood method. The averageQ c value at low frequencies (up to 2 Hz) is one of the lowest in the world, which is in harmony with the geological setting of the site condition directly above an active fault.
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Takahara, M., Yomogida, K. Estimation of codaQ using the maximum likelihood method. PAGEOPH 139, 255–268 (1992). https://doi.org/10.1007/BF00876330
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DOI: https://doi.org/10.1007/BF00876330