Causes

The 2011 Tōhoku Earthquake and Tsunami was a magnitude 9.0 earthquake and tsunami that struck near the northeastern coast of Tōhoku, Japan. The magnitude 9.0 earthquake occurred at 14:46 local time on Friday, 11 March 2011, 125 km east coast of Honshu and 380 km far from Tokyo and rattled the large parts of Japan, as well as eastern parts of China and far east Russia.

This earthquake that lasted approximately 3 minutes (170 seconds) caused a 130 km long by 159 km wide rupture zone on the pacific plate subduction zone and followed by a huge tsunami with more than 40 meter waves. This tsunami in turn crashed into Japan, as well as breaking the sea walls at the Fukushima Nuclear Plant, causing nuclear meltdowns on three of the four reactors. The physical destruction, economic cost, and loss of life are without precedent in Japan’s post-World War II history. These three disasters that wreaked havoc on Japan in 2011 are often known as a "triple disaster" - earth, water and nuclear.

Earthquake
The earthquake was caused by the subduction of the Pacific tectonic plate under the plate that Japan is on. The fault that lies at the boundary of the two plates is called the Japan trench. At the Japan trench, the two tectonic plates moved past each other approximately 80 metres. The earthquake ocurred as a result of the built-up tension between the two plates. This earthquake also triggered a tsunami soon after.

Tsunami
The tsunami was a direct result of the earthquake that occurred in the same area. The earthquake resulted in a vertical displacement of seawater, which then spread throughout the Pacific ocean, affecting areas as far as Chile. The tsunami ravaged the Fukushima Prefecture, resulting in the Fukushima Daiichi nuclear meltdown, resulting in the leakage of more than 300 metric tonnes of contaminated water.

Nuclear disaster
The Fukushima nuclear disaster occurred in the aftermath of the tsunami. Four of the six reactors at the Fukushima Daiichi plant were damaged, and began to leak hazardous materials.