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Research Letter
Large air pressure changes triggered by P-SV ground motion in a cave in northern Taiwan
Chieh-Hung Chen
China University of Geosciences
Corresponding Author
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A barometer in the cave of the SBCB station records an unusual phenomenon of larger amplitudes in air pressure changes inside than those at the Xinwu station (outside). Accordingly, the comparison between the recorded data at the SBCB and Xinwu station can drive investigations of potential sources of the unusual phenomenon. Analytical results of phase angle differences reveal that the air pressure outside the cave at the Xinwu station often leads air pressure changes inside at the SBCB station at relatively low frequency bands. In contrast, the larger pressure changes at frequencies > 2×10-4 Hz inside the cave at the SBCB station lead smaller changes outside at the Xinwu station. To expose causal mechanisms of the unusual phenomenon, continuous seismic waveforms recorded inside the cave at the SBCB station are further conducted for examination. When the horizontal and vertical ground velocities of ground motion yield a difference in the phase angle close to 90°, amplitudes of the air pressure changes at the SBCB station are amplified accordingly. This suggests that the pressure-shear vertical ground motion can drive air pressure changes. Meanwhile, the results shed light on investigating the existence of acoustic waves near the Earth’s surface using a partially confined space underground due to that the assumptions of the waves can propagate upward in the atmosphere driving changes in the ionosphere.
Keywords
Air pressure, Pressure-Shear vertical waves, Acoustic waves
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This is a preprint. It has not completed peer review.
Research Letter
Large air pressure changes triggered by P-SV ground motion in a cave in northern Taiwan
Chieh-Hung Chen
China University of Geosciences
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 2
Posted 05 Jan, 2021
No community comments so far
No comments provided
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Geophysics
License:
This work is licensed under a CC BY 4.0 License. Read Full License
A barometer in the cave of the SBCB station records an unusual phenomenon of larger amplitudes in air pressure changes inside than those at the Xinwu station (outside). Accordingly, the comparison between the recorded data at the SBCB and Xinwu station can drive investigations of potential sources of the unusual phenomenon. Analytical results of phase angle differences reveal that the air pressure outside the cave at the Xinwu station often leads air pressure changes inside at the SBCB station at relatively low frequency bands. In contrast, the larger pressure changes at frequencies > 2×10-4 Hz inside the cave at the SBCB station lead smaller changes outside at the Xinwu station. To expose causal mechanisms of the unusual phenomenon, continuous seismic waveforms recorded inside the cave at the SBCB station are further conducted for examination. When the horizontal and vertical ground velocities of ground motion yield a difference in the phase angle close to 90°, amplitudes of the air pressure changes at the SBCB station are amplified accordingly. This suggests that the pressure-shear vertical ground motion can drive air pressure changes. Meanwhile, the results shed light on investigating the existence of acoustic waves near the Earth’s surface using a partially confined space underground due to that the assumptions of the waves can propagate upward in the atmosphere driving changes in the ionosphere.
Figure 1
Figure 2
Figure 3