Frictional Control on Accelerating Creep During the Slow‐To‐Fast Transition of Rainfall‐Induced Catastrophic Landslides

• Published in: Journal of geophysical research. Earth surface 2024-01, Vol.129 (1), p.n/a
• Main Authors: Paul, Krishnendu, Bhattacharya, Pathikrit, Misra, Santanu
• Format: Article
• Language: English
• Subjects: Acceleration; Approximation; Catastrophe theory; Catastrophic failure analysis; Clay; Clay soils; Constitutive equations; Constitutive relationships; Extreme weather; Frequency variation; Gravity; Laboratory experimentation; Laboratory experiments; Landslides; Landslides & mudslides; Mathematical models; Parameter sensitivity; Parameters; Pore pressure; Pore water pressure; Precipitation; Pressure; Pressure changes; Pressure variations; Rainfall; Rigid blocks; Seasonal variation; Seasonal variations; Shear; Shear strength; Sliding; Slumping; Snowmelt; Soil; Soils; Solifluction; Velocity
• ISSN: 2169-9003; 2169-9011
• DOI: 10.1029/2023JF007213

Slow moving landslides regulated by precipitation/snowmelt induced subsurface pore‐pressure transients can sometimes accelerate to catastrophic failure causing loss of infrastructure and lives. Yet, unified theories of the transition of slow landslides into ultimately catastrophic ones in response to pore‐pressure changes remain relatively unexplored. Here, we use a simple gravity‐driven block‐slider model governed by laboratory‐derived rate‐and‐state friction (RSF) equations with velocity‐weakening parameters to analyze the mechanical progression of initially creeping landslides toward runaway acceleration. The rigid‐block approximation allows for exact or semi‐analytical estimates of the timescales over which such, potentially unstable, creeping landslides can be expected to transition to runaway acceleration in response to idealized pore‐pressure perturbation histories. We demonstrate that the duration of creep preceding catastrophic failure is critically sensitive to the RSF parameters, pore‐pressure variation amplitude and frequency, and background shear‐load and pore‐pressure levels through a set of non‐dimensional numbers. Our model predicts that slow landslides within velocity‐weakening clay‐rich soils can potentially creep for years to decades before transitioning to runaway failure when regulated by typical seasonal pore‐pressure transients. Remarkably, for much larger and rapid pore‐pressure changes, the same landslides can evolve to runaway failure over days to few tens of minutes. Being dependent purely on soil parameters that can be inferred from routine laboratory experiments, our model provides a theoretical framework that might be practically useful to understand the non‐linear and hysteretic response of landslide motion to pore‐pressure transients. Plain Language Summary Landslides, especially within clay‐rich soils, can creep for years before accelerating to catastrophic failure in response to subsurface pore‐pressure changes. While we now know slow landslides are common and occasionally evolve into fast ones, the details of this slow‐to‐fast transition remains poorly understood. Here, we explore the transition from slow to fast motion in creeping landslides using a theoretical model that assumes the landslide‐mass as a rigid block sliding under gravitational forces on a slope. The shear resistance to sliding is assumed to be determined by changes in soil pore‐pressure due to rainfall coupled to variable frictional strength governed by e