Landslide seismic signal recognition and mobility for an earthquake-induced rockslide in Tsaoling, Taiwan

• We recognize the Tsaoling landslide signal from Chi-Chi earthquake seismic record.
• We identify the initiation, slide, and landing times of landslide from a seismic signal.
• High frequency, 30–70 Hz, corresponds to rockslide initiation and sliding process.
• Results of sliding block analysis are consistent with the seismic signal processed.
• High sliding velocity of rock was enough to carry the mass across the valley.

Landslide seismic signal processing and the Newmark's sliding block analysis are used in this research to analyze the initiation time and mobility of the Tsaoling rockslide triggered by the 1999 Chi-Chi Earthquake in Central Taiwan. A new technique, the time–frequency spectrum analysis, is employed to identify the rockslide initiation and landing times from four real time seismic records of strong ground motion stations. The results suggest that higher frequencies ranging from 30 to 70 Hz correspond to the rockslide initiation and sliding process, which are opposed to the low signal frequency of earthquake. The landslide began at 32.5 s, the sliding block sped up at 37.5 s, and impacted on the opposite riverbank at 76 s on the seismic time record. The mobile scenario of Tsaoling rockslide induced by Chi-Chi Earthquake is simulated using Newmark's sliding block analysis. The maximum sliding velocity reaches approximately 75.1 m/s. Despite being a simple conceptual model, the Newmark's sliding block analysis provides consistent results with the real time seismic signal analysis and details of the rockslide kinematics.