Monochromatic infrasound waves observed during the 2014–2015 eruption of Aso volcano, Japan
| Autor: | Takahiro Ohkura, Keehoon Kim, Kyoka Ishii, Akihiko Yokoo |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
The 2014-2015 eruption
010504 meteorology & atmospheric sciences Infrasound lcsh:Geodesy 010502 geochemistry & geophysics 01 natural sciences Seismic wave The 2014–2015 eruption Electrical conduit Impact crater Air resonance in the conduit Waveform 0105 earth and related environmental sciences lcsh:QB275-343 geography geography.geographical_feature_category lcsh:QE1-996.5 lcsh:Geography. Anthropology. Recreation Geology Monochromatic infrasound wave Strombolian eruption Aso volcano in Japan lcsh:Geology lcsh:G Volcano Space and Planetary Science Monochromatic color Seismology |
| Zdroj: | Earth, Planets and Space, Vol 71, Iss 1, Pp 1-14 (2019) |
| ISSN: | 1880-5981 |
| DOI: | 10.1186/s40623-019-0993-y |
| Popis: | Monochromatic infrasound waves are scarcely reported volcanic infrasound signals. These waves have the potential to provide constraints on the conduit geometry of a volcano. However, to further investigate the waves scientifically, such as how the conduit shape modulates the waveforms, we still need to examine many more examples. In this paper, we provide the most detailed descriptions of these monochromatic infrasound waves observed at Aso volcano in Japan. At Aso volcano, a 160-day-long magmatic eruption occurred in 2014–2015 after a 20-year quiescent period. This eruption was the first event that we could monitor well using our infrasound network deployed around the crater. Throughout the entire eruption period, when both ash venting and Strombolian explosions occurred, monochromatic infrasound waves were observed nearly every day. Although the peak frequency of the signals (0.4–0.7 Hz) changed over time, the frequency exhibited no reasonable correlation with the eruption style. The source location of the signals estimated by considering topographic effects and atmospheric conditions was highly stable at the active vent. Based on the findings, we speculate that these signals were related to the resonant frequencies of an open space in the conduit: the uppermost part inside the vent. Based on finite-difference time-domain modeling using 3-D topographic data of the crater during the eruption (March 2015), we calculated the propagation of infrasound waves from the conduit. Assuming that the shape of the conduit was a simple pipe, the peak frequency of the observed waveforms was well reproduced by the calculation. The length of the pipe markedly defined the peak frequency. By replicating the observed waveform, we concluded that the gas exhalation with a gas velocity of 18 m/s occurred at 120 m depth in the conduit. However, further analysis from a different perspective, such as an analysis of the time difference between the arrivals of infrasound and seismic waves, is required to more accurately determine the conduit parameters based on observational data. |
| Databáze: | OpenAIRE |
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