A natural gas extraction company controlled by energy giant Exxon Mobil sought to prove Wednesday that it is not to blame for a recent rash of small earthquakes in North Texas , telling a powerful state agency that it believes the earthquakes occurred naturally. XTO Energy submitted evidence to the Texas Railroad Commission, which regulates the state's massive oil and gas industry, during a hearing that will test the agency's willingness to suspend permits for injection wells based on seismology.