On January 10, 1976 a natural gas explosion and subsequent fire killed 20 people in Fremont, Nebraska, and destroyed a hotel and six adjacent buildings. The exact cause of the explosion is unknown, but the natural gas leak that preceded the explosion was caused by an underground pipe separation. The odor of the natural gas was first detected about four hours before the explosion, however, hotel employees were unable to reach gas company personnel for nearly two hours, even though they used emergency telephone numbers.
After the explosion, gas company personnel dug down into the ground and found a 2-inch plastic gas main had separated by about one quarter inch from a compression coupling. Investigation officials of the NTSB theorized that the natural gas leaking from this pipe separation had permeated the soil between this point and the hotel’s basement wall, and then seeped into the hotel’s basement.
NFPA members can download a Fire Journal article about the incident.