Japan Tsunami 2011
How tsunamis occur.
As one plate subducts below another (moves underneath), pressure builds for many years resulting in a section of the mega-thrust giving away. As this section gives away, it ruptures the ocean floor, resulting in a massive displacement of water, causing a tsunami.
Tsunamis are barely felt as a ripple on the ocean’s surface, but as the waves reach land, they increase in size as the water becomes shallower.
Japan earthquake and tsunami
At 2:46pm Japanese time, on March 11th 2011, an earthquake with the magnitude of 9.0 took place 100km of the coast of Japan, and was the 5th most powerful earthquake ever recorded. It was caused by the Pacific plate and the Okhotsk plate. The Pacific plate has always been moving under the Okhotsk plate at a speed of 8.9cm a year, building up pressure (destructive plate boundary – continental and oceanic plate moving towards each other). Pressure being released caused the Pacific plate to snap back, releasing the pressure as an earthquake that lasted 5 minutes, and also causing a massive displacement of water, the result of which is a tsunami. The tsunami travelled at 500mph towards Sendai, and went up to 10km inland in the Sendai area, reaching a height of about 33ft. It reached Tokyo in 90 seconds from its original point 232 miles away. Tokyo had 60 seconds warning. Ofanato was hit 20 minutes after the earthquake, Onagawa and Sendai were said to be the most effected places. There were two other earthquakes after; one 26.6km off the coast of Hokkaido at 6:08pm local time. It measured 6.9 on the Richter scale, and was followed by a 20cm tsunami.
As one plate subducts below another (moves underneath), pressure builds for many years resulting in a section of the mega-thrust giving away. As this section gives away, it ruptures the ocean floor, resulting in a massive displacement of water, causing a tsunami.
Tsunamis are barely felt as a ripple on the ocean’s surface, but as the waves reach land, they increase in size as the water becomes shallower.
Japan earthquake and tsunami
At 2:46pm Japanese time, on March 11th 2011, an earthquake with the magnitude of 9.0 took place 100km of the coast of Japan, and was the 5th most powerful earthquake ever recorded. It was caused by the Pacific plate and the Okhotsk plate. The Pacific plate has always been moving under the Okhotsk plate at a speed of 8.9cm a year, building up pressure (destructive plate boundary – continental and oceanic plate moving towards each other). Pressure being released caused the Pacific plate to snap back, releasing the pressure as an earthquake that lasted 5 minutes, and also causing a massive displacement of water, the result of which is a tsunami. The tsunami travelled at 500mph towards Sendai, and went up to 10km inland in the Sendai area, reaching a height of about 33ft. It reached Tokyo in 90 seconds from its original point 232 miles away. Tokyo had 60 seconds warning. Ofanato was hit 20 minutes after the earthquake, Onagawa and Sendai were said to be the most effected places. There were two other earthquakes after; one 26.6km off the coast of Hokkaido at 6:08pm local time. It measured 6.9 on the Richter scale, and was followed by a 20cm tsunami.