| Volumes and Issues Contents of Issue 5 |
www.nat-hazards-earth-syst-sci.net/8/1139/2008/
doi:10.5194/nhess-8-1139-2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
Ground vibrations and airborne sounds generated by motion of rock in a river bed
1Department of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan, Taiwan
2Monitoring and Management Division, Soil and Water Conservation Bureau, Council of Agriculture, Nantou, Taiwan
Abstract. This study investigates how ground vibrations (underground sounds) and airborne sounds that are produced by rocks in a river bed differ from each other. Airborne and underground sounds were simultaneously received at three microphones and three geophones, respectively. These sound signals were then analyzed using both the Fast Fourier Transform and the Gabor Transform to represent them in both the frequency and time-frequency domains. Experimental data indicate that the frequency of both airborne and underground sounds produced by the impact of rocks against the river bed is in the range 10–150 Hz. Furthermore, the high-frequency band of underground sounds decays much more rapidly than that of airborne sounds. The spatial decay rate of airborne sounds was also determined and compared with theoretical values. The lower spatial decay rate of airborne sounds than that of underground sounds suggests that monitoring of airborne sounds may be more efficient in the detection of debris flows or other natural hazards that generate both airborne and underground sounds.
Full Article (PDF, 718 KB)
Citation: Huang, C.-J., Yeh, C.-H., Chen, C.-Y., and Chang, S.-T.: Ground vibrations and airborne sounds generated by motion of rock in a river bed, Nat. Hazards Earth Syst. Sci., 8, 1139-1147, doi:10.5194/nhess-8-1139-2008, 2008. Bibtex EndNote Reference Manager XML
