Remotely sensed survey of landslide clusters: Case study of Itaoca, Brazil

摘要

In January 2014, severe rainfall triggered landslides that buried 92 buildings and claimed 27 lives in the City of Itaoca (3000 inhabitants) in Brazil. The investigation of remotely sensed imagery and a ground-based weather radar shows a landslide cluster with 365 landslide scars over a quite uniformly vegetated background. The devastated area covers 33 km(2) with hillslopes ranging from 300 m to 1200 m in elevation, where intense rainfall reached 50 mm-170 mm within 2-6 h. The landslide slopes (median value at 26 degrees) are in general steeper for low rainfall intensities and longer rainstorm durations. Landslide clusters behave in response both to rainfall spatial distribution and land slopes. The total scar area of landslide clusters of given median slope exhibits a peak curve with maximum at the overall median slope. The individual scar areas exceedance probability follows a log-gamma distribution and the scar surface area increases with slide slopes.