Volcano (1997)

Continuity mistake: When the female nurse is in her 4x4 vehicle, she looks in her mirror and sees two fire trucks. In the far away shot the first fire engine overtakes her, then when it cuts back to her it's overtaking her again. (00:34:30)

Amy: Sometimes magma can find one of those fissures and rise up through it.
Roark: What's magma?
Rachel: Lava.
Roark: Lava? Right here in L.A?
Amy: It is one of the possibilities.
Roark: We have a history of that here in the downtown area?
Rachel: Paricutin... 1943, a Mexican farmer sees smoke coming out of the middle of his cornfield. A week later there's a volcano a thousand feet high. There's no history of anything until it happens. Then there is.

Trivia: The lava was primarily made of methylcellulose, the thickening agent used in fast-food milkshakes, and the ash was made mostly of ground newspaper.