Forecasting and mitigating natural hazards with remote and in-situ monitoring

Fast disasters happen slowly. Two of the most notorious “rapid-onset” disasters – earthquakes and landslides – have a common dependency on a single determining parameter known as the Gruntfest number. Deep-seated landslides, seemingly rapid-onset to the naked eye, have historically been monitored with in-situ monitors and borehole sampling to understand conditions within the shear band. These in-situ monitoring techniques, however, are high-cost and labor-intensive. As satellite data and resources expand, remote sensing has become a more cost-effective and realistic option for monitoring gradual ground deformation caused by the creep of a deep-seated landslide. Differential interferometric synthetic aperture radar (InSAR), specifically, can be used to measure displacements on the Earth’s surface with precision to a few centimeters or less. Here we use InSAR and pre-existing borehole data for the Canillo landslide in Andorra to characterize the evolution of temperature and thereby the Gruntfest number from August 2018-December 2021. Our results reinforce the characteristic models for deep-seated landslides in Segui et. al (2020), suggesting that there exists a critical Gruntfest value where the landslide is catastrophically unstable. Given the anticipated increase in extreme climate with climate change, we expect it to become more frequent for landslides to reach this critical Gruntfest value, therefore necessitating a more robust analysis of the evolution of the Gruntfest number and the overall destabilization process for future work.