There are several examples of large boulders having moved / fallen, found immediately following earthquakes. The one in this photograph is one example, which fell 15 m down the descent line of an entrance pitch just over 2 years ago (and was widely reported, including in Descent). I am aware of at least one caver fatality due to a falling boulder which is very likely to have been loosened by an earthquake a few days beforehand.
Cavers need to take these events seriously.