EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Rain and small earthquakes maintain a slow-moving landslide in a persistent critical state

Noélie Bontemps1, Eric Larose1, Pascal Lacroix1, Jorge Jara2, and Edu Taipe3
Noélie Bontemps et al.
  • 1Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD,IFSTTAR, ISTerre, Grenoble, France (
  • 2Laboratoire de Géologie, École Normale Supérieure, PSL Research University, Paris, France (
  • 3INGEMMET, Arequipa, Peru (

In tectonically active mountain belts, landslides contribute significantly to erosion. Statistical analysis of regional inventories of earthquake-triggered-landslides after large earthquakes (Mw>5.5) reveal a complex interaction between seismic shaking, landslide material, and rainfall. However, the contributions of each component have never been quantified due to a lack of in-situ data for active landslides. We exploited a 3-year geodetic and seismic dataset for a slow-moving landslide in Peru affected by local earthquakes and seasonal rainfalls. Here we show that in combination, they cause greater landslide motion than either force alone. We also show the rigidity of the landslide’s bulk clearly decreasing during Ml≥5 earthquakes. The recovery is affected by rainfall and small earthquakes (Ml<3.6), which prevent the soil from healing, highlighting the importance of the timing between forcings. These new quantitative insights into the mechanics of landslides open new perspectives for the study of the mass balance of earthquakes.

How to cite: Bontemps, N., Larose, E., Lacroix, P., Jara, J., and Taipe, E.: Rain and small earthquakes maintain a slow-moving landslide in a persistent critical state, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4464,, 2020

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