The recent natural avalanche is under the hanging cornice on the south ridge of Mt. Magog. It was likely triggered by natural cornice fall sometime in the last few days. The initial warmup causes large cornices to buckle and sag, and sometimes fail. Looks like a large piece fell off and triggered the avalanche on a drifted slope below. From a distance it appears to have failed on a buried persistent weak layer, most likely facets above a rain-crust from late January or early February.

Sorry about the poor quality photos, but they do show the avalanche if you look closely.