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Figure 8 | Earth, Planets and Space

Figure 8

From: Characteristics of dilatational infrasonic pulses accompanying low-frequency earthquakes at Miyakejima Volcano, Japan

Figure 8

Seismic signals and corresponding infrasonic pulses. (a) Seismic signals for the LF earthquake recorded on 29 October 2005 at 04:32 local time. The shaded bar indicates the uncertain onset of the seismic waveform. All waveforms are normalized relative to the maximum amplitude. The vertical axis corresponds to the epicentral distance of the stations from the vent in the caldera. The apparent seismic wave velocity was approximately 2.0 km/s. (b) Corresponding infrasonic pulses for the same earthquake. The shaded bar is the same as in (a). Note that high-frequency noise due to ground motion is superimposed on the signal before the onset of the pulse. The oblique dashed line, which connects the onset of the infrasonic pulse at each station, shows that the mean velocity was approximately 340 m/s. The arrow indicates the time of infrasonic excitation indicated by the source calculation. In both (a) and (b), the distance from the main vent with the topographical correction is shown on the vertical axis. Station codes are shown to the right of the traces.

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