A massive explosion shakes a small Texas town killing 15 people; a bridge in Washington collapses sending cars down into the river; a building demolition in Philadelphia goes terribly wrong.

Concertgoers are killed when a stage collapse at the Indiana State Fair; a possible gas leak levels two buildings and kills eight people in New York City; a train crossing is the site of two disastrous auto collisions in one year.

A 72 oil-car runaway train crashed, killing 47 people and leveling half a town; a huge sinkhole at the National Corvette Museum; 33 Chilean miners are trapped almost a half mile underground.

A storm of the century breaks nine dams in Colorado, flooding whole towns and leaving thousands stranded; A train transporting hazardous materials derails; A natural gas line breaks and reduces a neighborhood to ashes and rubble.

An explosion in a San Bruno, Calif. neighborhood demolishes homes and kills residents; A captain and crew sail their ship into the course of Hurricane Sandy; A building full of garment workers abruptly collapses and traps many of them inside.

Asiana flight 214, packed with passengers, suddenly crash lands; a huge explosion at a chemical plant outside Wichita, Kan.; dangerous sinkholes exist in 20 percent of the United States.