7 May 2021
The March 2011 landslides in Antonina and Morretes, Brazil
Jefferson de Lima Picanço and Dave Petley
On 10 and 11 March 2011 unusually intense rainfall affected the Paraná State coast at Antonina and Morretes in Brazil. This rainfall event killed four people and left two other missing, as well another 221 people injured.
The rainfall triggered large numbers of landslides, including translational slides on steep slopes, rotational slides and mudflows. Downstream there was extensive flooding and large volumes of sediment were deposited. The images below show of the landslides triggered by this event:-
These landslides were translational slides on the interface between bedrock and regolith in stepp upland catchments. Note how they have been channelised to form flows that appear to have eroded large volumes of sediment out of the channels.
Unsurprisingly the effects on the channels downstream were profound:-
Landslides also occurred on smaller slopes close to houses, causing substantial levels of damage:
In the lowland areas, the sediment released by the landslides caused extensive damage through inundation and deposition: