CARACAS, Venezuela — In the wooded neighborhood of La Boyera, at the feet of a mountain known as “the volcano,” Elena Berti was sleeping deeply early Saturday when everything began shaking so violently that the head of her bed frame toppled down on her.

Berti, 78, recalled rising from her bed, rosary beads in hand, and looking outside at a scene that seemed incomprehensible: The woods beyond her back patio were on fire.