Law-giver and orator simile
Unca imagines having the respect and attention of the island-dwellers, saying "whilst like a law-giver, I uttered precepts, and, like an orator inculcated them with a voice magnified almost to the loudness of thunder." She uses this simile to emphasize the power she would like to have, using the terms "law-giver" and "orator" as they are familiar to the reader.
Earthquake metaphor
The earthquake is metaphorically described as shaking the island, which makes it seem powerful and threatening. In this metaphor, the earthquake is personified, which intensifies this sense of threat, making it seem more immediate.
