Other mistake: Roark burns his hand on a hot frying pan and drops it to the floor. The dog then immediately wanders in to eat the spilled food. The pan should still be scorching hot after a short time, and yet the dog licks it without burning its tongue. (00:03:30)
Other mistake: The subway scene shown at the beginning of the movie during the opening credits is also used just prior to the big earthquake. (00:01:25)
Other mistake: During the first major tremor, the city suffers a complete blackout with no lights showing. The city goes completely dark but there are suddenly no car headlights visible either... (00:26:30)
Other mistake: Just before the lava begins to flow, the glass in a building shatters and falls on Roark and the doctor but neither suffer so much as a cut. (00:38:15)
Other mistake: When they are trying to find a way to stop the lava from going in to the museum, Tommy Lee Jones has an idea to push a bus up against the museum to divert the lava. The plan works but the lava does not melt the bus like it melted Tommy Lee Jones' car or the fire truck.
Answer: Lava is extremely hot. It heats the air above and around it to such a degree that it can reach the flash point of various items.
Greg Dwyer