That's an interesting link, between earthquake tremors and rockfalls in the region generally, and the "Scylla & Charybdis" descriptions. Where did Mark F. post this, Kefalas? I'll go looking myself, but I am new here and may not find his posting easily in the forum structure, so I'd appreciate your pointer.
I am a San Francisco native, and I've spent a lot of time in "earthquake country" in various places -- Guatemala, Nicaragua, Japan, Greece -- and so I can attest: "fear of falling rocks" plays a large subconscious role in everything that goes on, in such places, including the imagery used in local literatures. Most San Francisco writers work the theme in, somewhere; most in the other places do too, I would guess.
In Strabo's case much depends on his precise description, if the link to Paliki is to be made -- anything too general could be located anywhere in the Mediterranean. But in the book's Strabo chapter (#6, p. 48ff) his accuracy about remote Britain is pointed out, implying accuracy elsewhere, and he seems very precise in describing the location of his "channel": "Where [Kefalonia] is narrowest it forms an isthmus so low-lying that it is often submerged from sea to sea" (p.52) -- seems little doubt he meant Paliki.
does it get, on Kefalonia in the summertime? I'd like to see that Myrtos beach you describe here, someday, but my wife doesn't like hot weather...