Latest updates from the Guardian live blog:
• There has been an explosion at the Fukushima No 1 nuclear power plant in north-eastern Japan, close to the epicentre of the quake.
•Tens of thousands of people in the areas surrounding Fukushima No 1 and No 2 plants have been urged to evacuate.
• Japanese authorities are preparing to distribute iodine to residents in the evacuation zones to protect them against radiation exposure.
•Dozens of aftershocks, some as strong as magnitude 6, struck Japan on Saturday. Japan's state broadcaster has warned people in coastal areas that there could be further tsunamis.
•Around 1,700 people are estimated to have been killed, according to local media reports, but that death toll is expected to rise dramatically.
•Around 9,500-10,000 people are missing in the town of Minamisanrikucho in Miyagi prefecture, according to Japanese news reports.
•More than 215,000 people are in emergency shelters and around 50,000 rescuers have been deployed across the country.
•At least 1.4m homes are without water and around three million are without power.