A significant event has occurred in Inca City. The layer of seasonal ice has started to develop long cracks . This is visible in the orange-colored band adjacent to the araneiforms. Fans of dust are emerging from long linear cracks. The cracks form when large plates of ice have no easily ruptured weak spots to release the pressure from gas building up underneath, so the ice simply cracks.
There are also more fans on the ridge at the top of the image, and more have appeared in between the araneiforms. We do not have any analogous processes occurring naturally on Earth: this is truly Martian.
Written by: Candy Hansen (13 November 2014)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_038299_0985
Image: NASA/JPL/University of Arizona