Fig. 6.
From: Detection of seismic events triggered by P-waves from the 2011 Tohoku-Oki earthquake
The Kolmogorov-Smirnov two-sample test showing the two-sided probability of exceeding the difference of two samples calculated under the null hypothesis of equal distributions. Two samples refer to the spectral ratios in a local specific region and a large region. The probability is substituted for its complementary probability if the difference between the empirical cumulative distribution function of the local sample minus that of the regional sample is positive. The high probabilities in red show regions for which the spectral ratios are significantly large and the low probabilities in blue show regions for which the spectral ratios are significantly small.