Tsunami

The Tsunami was brought on by the upthrust of 6 to 8 metres of the Earthquake. Despite around 43% of Japans coast being protected by seawalls, many of the seawalls, when confronted with the tsunami, were overwhelmed. Thousands of lives were lost and the the impact was felt by all countries on the Pacific Ocean. Chile's Pacific coast, the furthest from Japan's, experienced 2 metre waves, whilst the waves were approximately 40 metres at its highest point in Japan.

The impact of the tsunami was mostly focused on the Tōhoku region of northeastern Honshu, where vast areas of land were inundated and the port and airport of Sendai city were forced to shut down operations. Apart from damaging roads, buildings and other basic infrastructure, the tsunami damaged four reactors at the Fukushima I power plant, triggering a nuclear disaster comparative to the Chernobyl meltdown in 1986.

Cause
The tsunami was a direct result of the earthquake that occurred in the same area. The submarine earthquake struck off the coast of Oshika peninsula and, though it caused severe damage across the Tōhoku region, it caused even more damage through its triggering of the tsunami.

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 at the seaside Fukushima Daiichi power plant. Even though the the complex had a sea wall protecting it, the damage eventually caused the leakage of more than 300 metric tonnes of contaminated water.

Impact
More than 18,000 people were killed in the tsunami, with most dying by drowning.

The first waves of the tsunami hit Japan less than 1 hour after the earthquake. The tsunami waves reached run-up heights (how far the wave surges inland above sea level) of up to 128 feet (39 meters) at Miyako city and traveled inland as far as 6 miles (10 km) at Sendai. The tsunami flooded an estimated area of approximately 217 square miles (561 square kilometers) in Japan.

The waves overtopped and destroyed protective tsunami seawalls at several locations. The massive surge destroyed three-story buildings where people had gathered for safety. Near Oarai, the tsunami generated a huge whirlpool offshore, captured on video, causing even more damage.