An earthquake with a preliminary magnitude of 6.7 rattled the coast of northern Japan, according to the U.S. Geological Survey. The quake occurred 31 miles southeast of Shuznai early Thursday local time, but no tsunami warnings were immediately issued, the Associated Press reported. There were no immediate reports of casualties or major damage.
Northern Japan experienced a previous earthquake Monday, which occured west of Hokkaido island, CBS News reported. That earthquake registered 6.1.
Earthquakes with magnitudes of 4.5 or higher are intense enough to be recorded in seismographs around the world. A magnitude 6.7 earthquake can cause serious damage, floods and tsunamis. Magnitudes measure the energy coming from the source of the earthquake. Experts caution that after an earthquake, secondary shockwaves can occur days or even weeks after the main earthquake, and are powerful enough to cause building damage.