The famous 1906 San Francisco Earthquake in North California was affected more by the fires than the earthquake itself.

From wiki:

"It has been estimated that up to 90% of the total destruction was the result of the subsequent fires.Within three days, over 30 fires, caused by ruptured gas mains, destroyed approximately 25,000 buildings…"

https://en.wikipedia.org/wiki/1906_San_Francisco_earthquake#Fires