the earthquake started a tsunami warning for japan's pacific coast and other countries, including new zealand, australia, russia, guam, philippines, indonesia, papua new guinea, nauru, hawaii, northern mariana islands (usa) and taiwan. the tsunami warning issued by japan was the most serious on its warning scale. it warned that the wave could be as much as 10 meters high. a 0.5 meter high wave hit japan's northern coast. kyodo news agency reported a four-metre-high tsunami hit the iwate prefecture in japan. miyagi prefecture was flooded, with waves carrying buildings and cars along as they travelled inland. in some areas the waves reached 10 km inland.