Skip to content

Modelling landslide dynamics of the pore-pressure induced 2012 Te Maari debris avalanche.

Juliette Vicente , Stuart Mead.

Abstract

Pore-fluid pressure plays a crucial role in initiating volcanic landslide and influencing material rheology during runout. A companion study (Vicente et al, in review) investigating the preparatory and triggering factors of the 2012 debris avalanche at Te Maari (Tongariro, New Zealand) suggests that the failure was likely initiated by a pore-pressure increase in the upper layers, resulting from fluid infiltration at depth. Based on this study, we explore the impacts of such initiation processes on flow dynamics and emplacement through numerical modelling. Unlike conventional dam-break models which assume an instantaneous and finite initial force imbalance to trigger landslide motion, D-Claw employs a statically balanced initial state. Motion is triggered by gradual changes, such as a basal pore-fluid pressure increase, progressively reducing the effective frictional resistance of the slope. This approach offers a more realistic simulation of natural landslides, typically triggered by rainfall, snowmelt or groundwater flow. We use D-Claw to simulate the complex flow dynamics of the Te Maari pore-pressure-induced landslide and compare the results with field data and other depth-averaged mass-flow models, including the single-phase Voellmy-Salm model and models that account for granular-fluid interactions, such as those by Pitman and Le (2005) and Pudasaini (2012). Similar to previous applications of D-Claw, such as the Oso landslide simulations (Iverson et al., 2015, Iverson and George, 2016), the Te Maari simulations demonstrate that landslide mobility is largely affected by the evolution of pore pressure during the flow, which is strongly dependent on initial conditions (e.g. initial solid volume fraction, permeability).