At least 19 people are dead after a 7.3-magnitude earthquake hit the southern Japanese city of Kumamoto - the second major quake to strike the area in two days.
NHK TV reported that 760 people have been admitted to hospital following the latest tremors, and almost 200,000 homes are without power, while drinking water systems have failed.
The quake hit at 1:26am on Saturday (local time), just over 24 hours after a 6.2 tremor killed 10 people in the same region. The Japanese Meteorological Agency initially issued a tsunami alert but later lifted it.
Some 70,000 people have been forced to leave their homes because of the earthquakes. Chief cabinet secretary Yoshihide Suga said: "We are making every effort to respond. Please let's help each other and stay calm."
Despite the reports of damage, experts said there was nothing irregular reported at the three nearby nuclear power plants.
The region's transport network suffered considerable damage, with one tunnel caved in, a highway bridge damaged, roads blocked by landslips and train and air services halted.
Sky correspondent Sean Dilley stated that damage to buildings, including a local dam, have led the country's Prime Minister ShinzÅ Abe to send as many as 15,000 troops to the area.
Mr Abe stated that the extra troops would assist with "the rescue, evacuation and life-saving operations".
