CITIZEN ALERT - EXPLOSIONS DO HAPPEN - SEE Underground Gas Pipeline Leaks: (NTSB) National Transportation and Safety Boards (1969-2014)

Liquid Natural Gas (LNG), Methane and Gasoline leaks and explosions do happen.  
www.NTSB.Gov investigators write official reports, and summarize dangerous patterns, and change the rules to prevent them.  This page links to 121 such reports since 1969.