Japan Tsunami 2011 free essay sample

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. We will write a custom essay sample on Japan Tsunami 2011 or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page 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. The other occurred almost 3 hours after the first earthquake. It measured 5. 7 on the Richter scale, and struck 90km east of Tokyo. Outcomes: 9,079 deaths, 2,628 injured, over 12,000 missing. The final death toll was 15,883. Coast line lowered over 1 metre, rendering the sea walls at Miyako useless. Moved portions of northeast Japan closer to North America by 7. 9ft. Earthquake shifted the Earth’s axis 25cm, and sped up the rotation, shortening the day by 1. 8 microseconds. Towns such as Ofunato and Kuju are said to have been â€Å"swept away†. Cities such as Miyako, Onagawa, Namie, and many more had been destroyed. Early estimates put the economic loss at about $14. 5 $34. 6 billion from the earthquake alone. Full economic loss estimated at $171 – $183 billion. At least 3 nuclear power stations faced explosions; the energy released was equivalent to 9. 32 teratons of TNT. Tsunami was equivalent to 1 million swimming pools being emptied on Japan. The Fukushima nuclear disaster. Said to be the worst atomic accident since Chernobyl 1986. The tsunami knocked out the cooling system’s power supply. Resulted in 10,000 tonnes of contaminated water going into the sea. Massive atmospheric emissions hit peak on March 15th and remained high until March 19th. Surrounding areas were evacuated and was only deemed safe on December the 16th. How did they try and stop it? 10 metre high sea walls in Miyako. The people of Miyako are used to tsunami drills. Hawaii research centre sent out pager messages when detected. Warnings shut down the nuclear reactors. However, the reactors need time to cool. Tectonic Plates. The Earth is made up of 4 layers: inner core, outer core, mantle, and the crust. The crust is made up of Tectonic plates that are constantly in motion. The inner core is the centre of the Earth. It’s a solid made from mostly iron and nickel. The outer core is the liquid layer surrounding the inner core. The mantle is the widest section of the Earth. Made from a semi molten rock called magma. The crust is the outer layer of the earth. It’s fairly thin and made of solid rock. There are two types of crust: continental crust which carries land, and oceanic crust, which carries water. The Earth’s crust is broken up into plates. Heat rising and falling in the mantle creates convection currents, generated by the radioactive decay of the core. The convection currents move the plates. Where the convection currents diverge near the Earth’s crust, the plates move apart. Where the currents converge the plates move together. The movement of the plates and activity inside the Earth is called Plate Tectonics. Plate tectonics cause earthquakes and volcanoes. The point where two plates meet is called a plate boundary. Earthquakes and volcanoes are most likely to occur on or near plate boundaries. Different kinds of plate boundaries. At a constructive plate boundary, the plates move apart. At a destructive plate boundary, the plates move together. At a conservative plate boundary, the plates slide past each other. Constructive. As the plates move apart (very slowly), magma rises from the mantle. The magma erupts to the surface of the Earth. This can also be accompanied by earthquakes. When them magma reaches the surface, it solidifies to form a new crust of igneous rock. Eventually the new rock builds up to form a volcano. Constructive boundaries tend to be found under the sea, e. g. The Mid Atlantic Ridge. Here, chains of underwater volcanoes have formed along the plate boundary (where the tectonic plates meet). Underwater volcanoes, over time, can grow large enough to become volcanic islands, e. g. The Hawaiian islands. Destructive. At a destructive plate boundary, the plates move towards each other. This usually involves and continental and an oceanic plate. The oceanic plate is denser than the continental plate, so when they move together, the oceanic plate is forced underneath the continental plate, the point at which is called the subduction zone. As the oceanic plate is forced under the continental plate, it melts into magma, and the earthquakes are triggered. The magma collects to form a magma chamber. This magma then rises through the cracks in the continental crust. As pressure builds, a volcanic eruption may occur. Destructive plate boundaries can also form mountains. As the plates move together, the continental crust is squashed together and forced upwards. This is called folding. The process of folding creates Fold Mountains. Fold Mountains can also be formed when two continental plates push together. This is how mountain ranges such as the Himalayas and the Alps were formed. Conservative. At a conservative boundary, nothing’s formed and nothing’s destroyed. The plates lock together and pressure builds. As the pressure is released, earthquakes are triggered. An example is the Pacific plate (faster moving) rubbing against the North American plate. This causes earthquakes along the San Andreas Fault line, disturbing cities such as Los Angeles and San Francisco. Earthquakes. Earthquakes are caused by the release of built up pressure in the Earth’s crust. An earthquake’s power is measured on the Richter scale using an instrument called a seismometer. An earthquake is the shaking and vibration of the Earth’s crust. Plates don’t often move smoothly together and sometimes get stuck. When this happens pressure builds up. When pressure is finally released, there is generally and earthquake. Earthquakes can happen along any type of plate boundary. The point inside the Earth’s crust where the pressure is released is called the focus. The point on the Earth’s surface above the focus is called the epicentre. Earthquake energy is released in seismic waves. These waves spread out from the focus. The waves are felt most strongly at the epicentre, weakening as you get further away. Most of the severe damage caused by an earthquake happens at the epicentre. Effects of an earthquake. Earthquakes can destroy settlements and kill many people. Aftershocks can cause even more damage to an area. We can classify the impacts of an earthquake by taking the following into account: Short-term (immediate) impacts. Long-term impacts. Social impacts (impact on the people) Economic impact (impact on the areas wealth) Environmental impacts (the impact on the landscape) Social Economic Environmental Short-Term Deaths and injuries, homes destroyed, transport and communication links disrupted, water pipes burst – water contaminated. Shops and business destroyed, looting, damage to transport. Built landscape destroyed, fires, landslides, tsunamis. Long-Term Disease spreading, people re-housed (sometimes in refugee camps) Have to rebuild everything, income lost, all money spent on repairs. Important landmarks lost. Effects are classified as primary and secondary impacts. Primary effects occur as a direct result of the ground shaking e. g. buildings collapsing, liquefaction etc. Secondary effects occur as a result of primary effects, e. g. fires due to ruptured gas mains. Factors effecting the impact. Distance from the epicentre. How severe the earthquake is. Areas level of development (MEDC or LEDC) – MEDCs are more likely to have the resources and technology for prediction, monitoring, and response. Population density (rural or urban), the more densely populated, the more likely deaths will be. Communication – access to rescue. Time of day – at night people will be in bed, unprepared. Time of year – climate influences survival rate and the rate disease spreads. In LEDCs Undeveloped communication systems. Population uneducated on precautions. Poor construction standards. Evacuation difficult due to lack of funds and resources. Cleaning and repair difficult due to lack of funds. Measuring earthquakes. The power of an earthquake is measured with a seismometer. A seismometer detects vibrations caused by an earthquake. It plots these vibrations with a seismograph. The strength or magnitude of an earthquake is measured on the Richter scale. The Richter scale is numbered 0-10. Earthquakes measuring 1-2 are very common and people don’t even feel them.