It wasn't initially clear whether there were any injuries or deaths from Saturday's earthquake.
The quake's maximum intensity peaked at 7 in seismic intensity, the highest measured by the Japanese scale. It's the first time the country has measured such a high number since the 2011 earthquake and tsunami that killed tens of thousands.
As for Thursday's earthquake, thousands have been evacuated and thousands more left without power.
Japan's government has already held two emergency meetings since the quake hit. The country's prime minister said, "Rescue and relief activities for the affected individuals is a battle against time."
Japan is in a region known as the Ring of Fire where the tectonic plates make it more susceptible to earthquakes.