As Aron Ralston learned the hard way when his arm got pinned by a shifting rock while canyoneering in Utah, "Geology Happens". Notice the large boulders under the bluff in this location. They've all fallen from that bluff and one, towards the south end of this section, fell within the last five years! Some town folks both heard and felt it. The lichen/moss covered ones near ground zero have been here a long time and are in a relatively safe area. So have fun, grab the cache, but don't venture into the area south of here.
Getting accurate coordinates in the shadow of this bluff proved difficult so use the hint and your geo-sense to make the grab
And the "First To Find" HONOR goes to Arthur & Trillian