Dark area on Saunders Island

In the satellite image from 24th August 2015 a dark patch appears around the summit area of Mount Michael along with a dark strip which appears to originate from the dark patch and ending at the eastern side of the island. Although most of the dark patch could be the shadow from the peak, it looks as though something was happening and I wouldn't rule out an eruption.

Ash emission on 24th August 2015: SOURCE: NASA.