The 2005 West Off Fukuoka Seismic Sequence

Location map of 20 earthquakes for the West Off Fukuoka seismic sequence and the 4 stations used in this study. Red, orange, and black circles indicate the main event, the largest aftershock, and other aftershocks, respectively. Four F-net broadband stations are indicated with black triangles. The numbers in the parentheses represent the epicentral distance from the main event. Inset shows the focal mechanisms of the sequence.

Examples of the spectral ratio curves for coda-waves (red lines) and direct P-waves (gray lines). Two red and gray lines indicate ± 1 standard deviations of averaged ratios for four stations. Blue inverted triangles, red diamonds, gray triangles represent estimated corner frequencies from coda source spectrum, coda spectral ratio, spectral ratio of direct P-wave, respectively. Upper and lower black horizontal lines indicate low and high frequency asymptotes predicted by the self-similar omega-square source model by Brune (p=2), respectively. Dashed gray lines indicate high frequency asymptotes with high frequency decay rate p=1.5.

(a)  Corner frequency versus seismic moment for the Fukuoka sequence. Blue squares represent the corner frequencies and seismic moments determined from coda source spectrum method. Vertical and horizontal error bars represent 1 standard deviation for four stations. Orange squares represent the results obtained from coda spectral ratio mehtod. Red and black lines indicate the best fit regressions calculated from bootstrap test for blue and orange squares, respectively. For references, the grey lines for constant apparent stresses of 0.01, 0.1, 1, and 10 MPa are plotted. (b) Scaled energy versus seismic moment for the sequence. Scaled energy varies with seismic moment and a linear increment occurs between about Mw 4.0 and 5.0. Vertical and horizontal error bars represent 1 standard deviation for four stations.

References

Seung-Hoon Yoo, Junkee Rhie, Hoseon Choi, and Kevin Mayeda (2010), Evidence for non-self-similarity and transitional increment of scaled energy in the 2005 West Off Fukuoka seismic sequence, Journal of Geophysical Research-Solid Earth, 115, B08308. [PDF]