Japanese Tsunami
Earthquake a surprise
The unexpected disaster was neither the largest nor deadliest earthquake and tsunami to strike this century. That record goes to the 2004 Banda-Aceh earthquake and tsunami in Sumatra, a magnitude-9.1, which killed more than 230,000 people. But Japan's one-two punch proved especially devastating for the earthquake-savvy country, because few scientists had predicted the country would experience such a large earthquake and tsunami.
The cause
The 2011 Tohoku earthquake struck offshore of Japan, along a subduction zone where two of Earth's tectonic plates collide. In a subduction zone, one plate slides beneath another into the mantle, the hotter layer beneath the crust. The great plates stick and slip, causing earthquakes. East of Japan, the Pacific plate dives beneath the overriding Eurasian plate. The temblor completely released centuries of built up stress between the two tectonic plates, a recent study found.
The earthquake started on a Friday at 2:46 p.m. local time (5:46 a.m. UTC). It was centered on the seafloor 45 miles (72 kilometers) east of Tohoku, at a depth of 20 miles (32 km) below the surface. The shaking lasted about six minutes.
Deaths
More than 18,000 people were killed in the disaster. Most died by drowning
Nuclear meltdown
The tsunami caused a cooling system failure at the Fukushima Daiichi Nuclear Power Plant, which resulted in a level 7 nuclear meltdown and release of radioactive materials. About 300 tons of radioactive water continues to leak from the plant every day into the Pacific Ocean, affecting fish and other marine