Estimations of the S-wave velocity (⁠|${V}_{S}$|⁠) and attenuation strength (⁠|${B}$|⁠) based on the wave propagation pattern. Each red dot shows the results from different events. The dashed curves are contours of the quality factor (⁠|${Q}_{S}$|⁠) from 100 to 1000. A dominant frequency of 5 Hz was assumed. The acceptable ranges of |${V}_{S}$| and |${B}$| are highlighted in pale blue.