Observing Southern California Landslides Using UAVSAR: La Conchita as a
Case Study
Abstract
The La Conchita Landslide is infamous for its repeated devastation of
the coastal community in Southern California. The landslide caused
severe damage and loss of life once in 1995 and 2005. In this study we
use UAVSAR interferograms of the La Conchita area to identify any
residual motion or slope instability associated with the landslides.
UAVSAR is NASA’s airborne interferometric synthetic aperture radar
(InSAR) platform and is useful for imaging changes in the Earth’s
surface. UAVSAR repeat pass interferometry products show disturbances in
the image pairs that may correlate with landslides, including where the
La Conchita landslides had previously occurred. We used UAVSAR to
compare different line-of-sight velocity profiles of the landslide to a
stable area to the northeast. UAVSAR pairs show ongoing motion of up to
-0.14 cm/day average velocity years after the landslides occurred. More
stable areas show less than -0.06 cm/day maximum average velocity. The
results imply that damaged rock and soil of a landslide continue to move
relative to the surrounding more stable area. UAVSAR image pairs may be
useful for identifying unstable areas on slopes that may be associated
with landslides or other disturbances.