We have been monitoring the slope streaks on this hill for several years. There are definitive changes between this September 2018 image and a previous one in December 2016. Earlier streaks have since faded and new, darker streaks are visible. These streaks are tens of meters wide.
These features are small avalanches of dust and sand from the hillsides. The surface dust is lighter in color, but when it avalanches away, it reveals underlying larger-grained sand particles that are much darker. Over time, the dust slowly rains down from the atmosphere and the streaks fade as they are coated with dust.