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Figure 11 | Earth, Planets and Space

Figure 11

From: Active monitoring at an active volcano: amplitude-distance dependence of ACROSS at Sakurajima Volcano, Japan

Figure 11

Comparison between predicted and observed amplitude decay of ACROSS signal in Sakurajima. Plots of amplitudes are the same as in Figure 4, except for the single sinusoid at 10.01 Hz, which are converted to the equivalent value for the mean amplitude of FM operation between 10 and 15 Hz. The left panel shows the amplitude at each seismic station averaged over the receiver components. The right panel shows the amplitude averaged over the source excitations. Red and black curves are the predicted amplitudes estimated in this study. The red curve is calculated using the amplitude data of the shot experiment on Sakurajima Island only, and the black curves use all the amplitude data on and off Sakurajima Island. The source intensity for the curves is equivalent to that of the FM operation at 10 to 15 Hz, which is the operation frequency at Sakurajima. The source intensity is converted from that of ACROSS at Toyohasi, which is operated with frequency modulation at 10 to 20 Hz, based on the force-frequency relationship of centrifugal force.

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