[SCG62-P08] Temporal variation in Coda Q in the northeastern part of Niigata-Kobe Tectonic Zone in 2009-2014
Keywords:the 2011 Tohoku earthquake, high strain rate zone
We have analyzed 646 events in the period I and 2194 events in the period II in the northeastern part of the NKTZ. Those magnitudes are greater than 1.8 and the depths shallower than 30 km. For each station, we select events of which epicentral distance are within 30 km for the analysis of coda Q. We applied the single back-scattering model (Aki and Chouet 1975) for the estimation of coda Q.
We compare the obtained coda Q between the periods I and II. The change in log (coda Q-1) is smaller than 13% between the periods I and II. We investigate the spatial variation of the change between the periods I and II. Spatial distributions of increase log (coda Q-1) variation at 1-2 and 2-4 Hz frequency bands is volcanic area and it is difficult to find a distinct pattern of the spatial distribution of log (coda Q-1) variation at 4-8, 8-16, and 16-32 Hz frequency bands that is related closely to the fault zones, volcanic area, or the high strain rate zone. We apply t tests to analyze the significance of these temporal variations and find that little variations are statistically significant. These facts imply that the temporal variation in coda Q caused by the 2011 Tohoku earthquake is not significant in this study area.