Premise: MEXICO CITY Mexican President Felipe Calderon said on Tuesday, via his Twitter account, that there was no serious damage reported from a strong earthquake that hit near the country's western coast and shook buildings as far as the capital. Mexico City mayor Marcelo Ebrard said, also via his Twitter account, that he saw no damages as he surveyed the city from a helicopter. (Reporting By Mexico City Newsroom; editing by Jackie Frank)
Hypothesis: Mayor tweeted about the earthquake before or after the President's tweet.