The Tōhoku Earthquake and Tsunami Strike Japan

On 11 March 2011, at 14:46 local time, an undersea megathrust earthquake occurred in the Pacific Ocean roughly seventy-two kilometers east of the Oshika Peninsula in northern Japan. The tremor registered at magnitude 9.0 to 9.1 and the shaking lasted several minutes, making it the most powerful earthquake ever recorded in Japan and the fourth strongest worldwide since modern seismography began in 1900. Geologists attributed the event to the subduction of the Pacific plate beneath northern Honshu, where accumulated stress caused a sudden seabed slip that elevated the ocean floor by several meters.

The rupture triggered a massive tsunami, and a nationwide survey later found maximum run-up heights above ten meters along some 500 kilometers of the Japanese coast. The surge proved far more destructive than the tremor itself, echoing the disproportionate coastal toll seen during the 2004 Indian Ocean earthquake and tsunami. Water heights near Miyako reached close to 40 meters, the highest ever measured in a Japanese tsunami, while on the low-lying Sendai plain water spread several kilometers inland. Sea walls were overtopped and undermined, and many designated evacuation buildings were destroyed; in Minamisanriku alone, an estimated 31 of 80 were lost. Winter temperatures close to 0 °C added to the suffering of survivors.