Rockslides are among the most hazardous events, yet their hypermobility remains unclear (Wang, 2017). Friction-heating mechanisms — thermal pressurization, melting, and decomposition — have received wide attention (Goren et al., 2010). A key debate concerns the temperature required: melting and decomposition invoke T >1000°C, but experiments on landslide gouges seldom record T above several hundred degrees Celsius (Wang et al., 2017), implying high T may not be essential.
We conducted high-velocity friction tests on water-saturated gouge from the Dabanqiao rockslide (>3×10⁷ m³). Tests at 1.31 m/s, 4 MPa normal stress, and up to ~11 m shear displacement simulated basal shear zone dynamics.
μ dropped in transient spikes from ~0.4 to ~0.1 (<0.5 s) with dilation (Sps. in Fig. 1A–1B). Bubbles (Fig. 1C) noticed at shear displacement reached ~4 m, coinciding with T >100°C and spikes, suggest vaporization contributed to weakening.
The spikes are consistent with thermal pressurization: frictional heating drives vaporization, generating excess pore pressure that reduces normal stress and causes weakening. Rapid μ recovery suggests episodic fluid trap (Yao et al., 2023). Our tests demonstrate that thermal pressurization induced frictional weakening can be reached in saturated rockslide gouge at normal stress of 4 MPa and shear displacement of ~4 m. Meanwhile, the maximum T did not exceed 170°C (Fig. 1B). This indicates that thermal pressurization is a common weakening mechanism in water-rich, large rockslides.

thermal pressurization,frictional weakening,high-velocity friction tests,large rockslides,water-saturated gouge