Petrolia is located near the Mendocino Triple Junction, where three fault lines meet, and experiences frequent earthquake activity. The last large earthquake to affect the area was a magnitude 7.1 earthquake in 1992, which resulted in a fire that destroyed the Petrolia General Store. The store was rebuilt but lacks the charm of the 100-year-old landmark that it replaced. Two of the remaining landmarks in Petrolia are a small wooden church dating from 1912--St. Patrick's Catholic Church--and the Petrolia Pioneer Cemetery, which has the graves of original residents of Petrolia dating from November 1857.