No one was injured during the disaster near the town of Alta in northern Norway, and the dog was able to safely swim back to land, police spokesman Torfinn Halvari said.
Jan Egil Bakkedal, who owns one of the houses lost in the landslide, told the AP he was preparing a sandwich when he heard a huge noise and “ran for his life” into the surrounding hills.
Bakkedal filmed from atop a hill as a massive chunk of land with homes overlooking the sea broke off and slid into the waters. In a matter of seconds, many of the homes sank under the swirling waves.
The Royal Norwegian Airforce released footage of the 1-year-old dog, an elkhound called Raija, running out of the wreckage into the hands of rescuers. The dog was reunited with its owners.
Local police told Norwegian news agency NTB the landslide was between 2,145-2,640 feet (650 meters and 800 meters) wide and up to 132 feet (40 meters) high.
Several minor landslides followed, and nearby houses were temporarily evacuated.
The far end of the cape where the landslide occurred was closed off Thursday.
Alta Mayor Monica Nielsen said that “the extent of the damage is considerable, and there's a lot of debris.” Work was underway to ensure that the rubble doesn't end up in shipping lanes.
Landslides can be triggered by rainfall, snowmelt, changes in water level, stream erosion, changes in groundwater, earthquakes, volcanic activity, or disturbance by human activities.
The Associated Press contributed to this report.