The 2017 Tokai earthquake and tsunami was a catastrophic event caused initially by the Philippines Plate subducting beneath the Eurasian Plate, in which Tokai is located near. The cause of the tsunami was a magnitude 8.2 aftershock of a larger magnitude 8.7 earthquake that struck at 0419 UTC near Toyohashi off the Pacific Coast at a depth of 13 km. The first tsunami arrived 3 minutes after the 0421 UTC aftershock occurred at 10 km, on the bed of the Pacific Ocean. The first tsunami, 7 meters high reached the coast, it smashed hundreds of boats into matchwood, wiping debris 5km inland in the process. The generation of powerful aftershocks continued for 8 hours, which generated a further 6 tsunamis, which all travelled over the entire Pacific, where several of the islands were hit badly. Occurring when they did (Lunchtime in Japan), many people were out and about on their lunch breaks at the time the earthquakes and tsunamis hit, which then caused about 20,000 deaths and $144 billion in damages in Japan. Elsewhere, 113,447 deaths and $323 billion in damages were attributed to the events as they unfolded. In addition, 50 million people around the Pacific were made homeless by the tsunamis.

Forecasts and preparations

On January 19, 2016, the JMA released an update on the Tokai earthquake probabilities, and forecast an area off the Pacific Coast to be hit by a magnitude 8+ earthquake between November 9, 2016, and April 17, 2017. This entitled that all inhabitants of the country were to begin their preparations particularly in Tokai Prefecture where the earthquake was expected to hit. Supplies were gathered, and the number of earthquake drills being performed was also increased, and earthquake safety days were also held once a month leading up to the earthquake to make sure everybody was adequately prepared for the imminent shock.

On July 18, 2016, the JMA issued the earthquake report on the earthquake, which stated that radon levels were beginning to increase in water levels near the expected location of the shockwave. This continued, and by November 27th, and earthquake advisory wasw issued, stating that there would be an earthquake of at least 7.5 within a month. When this shock failed to materialize, and radon levels continued to increase, the possibility of immense pressure in the fault lines was passed.

This continued, and by January 14, 2017, the pressure began to be released as small earthquakes (foreshocks) began affecting the area around the expected earthquake location, and the JMA issued the general earthquake alert to the citizens of Tokai, stating that there could well be a magnitude 8.5 earthquake within 2 months, along with a tsunami at least 20 meters high, as the radon levels reached critical.

The earthquake

The earthquake occurred out of the blue, when the Pacific Plate suddenly slipped 14 meters underneath the Eurasian Plate, causing a powerful megathrust shockwave to rip under the plate, creating a new fault line in the area as a result of its violence. for 5 minutes, 27 seconds, the ground around the earthquake moved violently, producing maximum damage intensities of XI on the modified Mercalli scale, literally throwing buildings to the ground as a result. In fact, such was the violence of the shocks that the JMA was expecting a tsunami within 5 minutes of the shock, whereas, in fact, it was the 8.2 aftershock two minutes later that actually caused the tsunami, having been at a depth of 11 km, on the bed of the Pacific Ocean. The cause of the tsunami was a 6 meter uplifting of the ocean floor, along with a 12 meter lateral movement of the ocean floor along the subduction zone, which also created a new fault line under the Japanese Islands as a result

The tsunamis

A number of tsunamis occurred following the Tokai aftershock caused the Pacific Ocean to move violently to

the side and up. The first of these hit the Japanese coast at 0424 UTC, lunchtime in Japan. As a result, thousands of people died as a result of the tsunamis that followed. For the next 8 hours, more violent megathrust aftershocks caused lesser tsunamis to cross the entire Pacific Ocean, killing over 133,000 people in the process


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