Sand Avalanches in Meroe Patera
Science Theme: Aeolian Processes
Our image shows that sand dunes are massing at the base of the crater wall. The frost-coated crater wall reveals a surprise sand dune accumulation at the base of the CO2 coated walls. 
What caused These slumps?
Dry ice, which is thought to cause flows in some gullies and the North polar dunes, appear to be the leading candidates for these dry flows.
They are far larger than the avalanches commonly seen on sand dunes here on Earth. This lower part of the wall image, might have been triggered by a Mars-quake or an unusually strong wind.

Acquisition date:         03 February 2015
Local Mars time:         14:33
Range to target site from satellite:    279.2 km (174.5 miles)
Original image scale range:   27.9 cm/pixel so objects ~84 cm across are resolved
North is up
Sun about 41° above the horizon
Northern Winter