“You hear people say it sounds like a train, a jumbo jet, a very low growl,” Jonathan Stewart, whose home was hit by one of last week’s tornadoes, told WALA in Alabama. “The pressure changed.” Stewart and his family are among thousands of Americans affected by the series of tornadoes that tore across Georgia, Alabama, Tennessee and Mississippi last week. At the most recent count, at least 342 people are dead, more than 200 of them in Alabama. Towns have been flattened, homes and businesses wrecked beyond repair. “We have neighborhoods that have basically been removed from the map,” said Tuscaloosa, Ala., Mayor Walt Maddox at a press conference Thursday.

Last week, Google, in conjunction with the satellite imaging company GeoEye, captured and released satellite images of some of the impacted areas. These images, compared here with those of the same locations last fall, help to document one of the most violent tornado outbreaks in U.S. history.

Drag the green bar to see before and after images.

To further explore these maps, install Google Earth, and then download this Google Earth data file.