Landslide subsurface slip geometry inferred from 3‐D surface displacement fields

Abstract

The stability of many large landslides is determined in part by deformation along buried, often inaccessible, slip surfaces. Factors such as infiltrating rainfall on the slip surface lead to stability changes. Yet characterizing the depth and shape of this slip surface is challenging. Here we examine the hypothesis that the subsurface slip geometry can be constrained by ground surface displacements in concert with two, mechanically distinct, forward models. We estimate a 3-D ground displacement field for the slow-moving Cleveland Corral landslide in California using repeat terrestrial laser scanner data. We test the efficacy of two models to estimate slip depth and slip magnitude of the slide-a 2-D balanced cross-section method and an elastic dislocation model. The estimated slip surface depth using both methods matches in situ observations from shear rods installed in the slide within the ±0.45 m misfit indicating that these are valuable approaches for investigating landslide geometry and slip behavior.

Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides

“…However, elastic deformation can be significant for small displacement and strain over short timescales. Several studies have accounted for these effects to quantify key features of landslides, including landslide depth (17) and incipient motion (15,16). Because our model simulations describe small displacements and gradients in slip rate over short distances, the incorporation of elastic effects is both reasonable and appropriate.…”

“…a free surface). Although it is generally accepted that the weathered rock and soil that overlies the landslide slip surface does not behave elastically over long timescales or for large displacements, elastic deformation can be significant for small displacement and strain over short timescales (i.e., transient motion) (15)(16)(17).…”

Combining InSAR and GPS to Determine Transient Movement and Thickness of a Seasonally Active Low‐Gradient Translational Landslide

“…Existing noncontact methods for determining failure surface geometry and landslide volume, such as the balanced cross-section method (e.g., Aryal et al, 2015;Bishop, 1999), the dislocation model (e.g., Aryal et al, 2015;Nikolaeva et al, 2014), and the mass conservation approach (Booth et al, 2013;Delbridge et al, 2016;Huang et al, 2017), require only an analysis of 3D displacement maps. However, these methods vary in their accuracy based on the underlying model assumptions: the balanced cross-section method considers multiple cross sections independently without taking adjacent bodies into account, and the dislocation model largely simplifies the landslide geometrically and physically, employing a linear elastic model and a single rectangle planar basal surface (Nikolaeva et al, 2014).…”

Transient Reactivation of a Deep‐Seated Landslide by Undrained Loading Captured With Repeat Airborne and Terrestrial Lidar

“…Repeat topographic data have highlighted details of landslide kinematics (Corsini et al, 2007;Stumpf et al, 2015;Ventura et al, 2011), but these data are rarely capitalized on to infer landslide dynamics. Vertical changes or horizontal displacements can provide information about sediment budgets (DeLong et al, 2012), but three-dimensional (3-D) surface changes are generally needed to quantitatively infer subsurface characteristics of a landslide, where frictional processes govern its motion (Aryal et al, 2015;Booth et al, 2013). Furthermore, obtaining complete coverage of a landslide's surface displacement field at high resolution can be challenging because of heterogeneous displacements and erosion or deposition, which inhibit automated feature tracking.…”