The deadly cliff collapse in Encinitas last week raised questions about the stability of large swaths of the state that are lined by bluffs, many of which support houses or offer enticing patches of shade for families relaxing on the beach. Friday’s collapse, which killed three people, was a tragic consequence of sea cliffs’ natural erosion process, experts say. Chunks of bluffs regularly fall off to create the beach below, so all beach bluffs should be considered unstable, said Brian Ketterer, coastal division chief for California State Parks.