Since 2001, the Soil and WaterConservation Bureau, Council of Agriculture, Taiwan, has established 13 debris flow monitoring stations in debris flow potential areas. In each monitoring station, several observation instruments including rain gauges, CCD cameras, wire sensors, geophones, and water level meters were installed to collect the dynamic debris flow information. In this study, the ground vibrations generated by debris flows were detected using geophones and were analyzed to determine the characteristics. The time-domain signals of the debris flow ground vibrations were converted into frequency domain by the Fast Fourier Transform (FFT) and into time-frequency domain using the Gabor Transform. The results show that the ground vibration frequencies of debris flows are less than 150 Hz and they mainly fall between 5 to 100 Hz with multiple peak values. Following Gabor Transform analysis, the ground vibration spectrum distribution of debris flow reveals the phenomenon of the boulders gathering in the front surge of debris flows. The average velocity of debris flow surge was about 13.3 m/s as acquired from the measurements of the serial geophones. Besides, the location of the geophones has considerable influence on the signal intensity of the ground vibration caused by debris flows.