Conversation so far:
what is the town of centralia pennsylvania famous for
Centralia, Pennsylvania was once a bustling mining center, but a hidden, underground fire has turned it into a smoldering ghost town.
what kind of fire is happening underground in centralia, pennsylvania
The Centralia mine fire is a coal-seam fire that has been burning underneath the borough of Centralia, Pennsylvania,

Question: How deep
Self-contained rewrite: how deep is the centralia mine fire