To get an idea for the scale, a hand grenade rates about 0.5. This is one of the earliest earthquakes recorded in Japanese history. Along much of the Ring of Fire, plates overlap at convergent boundaries called subduction zones. The reason Japan has so many earthquakes is that a number of these plates converge below the country's surface. Worldwide earthquake distribution. Japan’s high number of earthquakes is due to its geographical location along the Pacific Ring of Fire (環太平洋火山帯, kantaiheiyoukazantai). This is also around the magnitude of the atomic bombs dropped by the United States in WWII. Finally, why do earthquakes occur at subduction zones such as Japan? The mantle melts at subduction zones because of the addition of volatiles, such as water and carbon dioxide. I accept your presentation on the issues, Please also analyse, how will we improve the knowledge of the natural disaster before know to the people, like the proverbs of; "prevention is better than cure". She currently works in industry. The frequency of earthquakes is inversely related to their magnitude. Ryukyu Islands (14 volcanoes): Akuseki-jima | Gajajima | Iriomote-jima | Iwo-Tori-shima | Kikai | Kobi … The quake mostly affected the capital of Asuka and killed upwards of 1,000 people, a considerable death toll for the time period. Earthquakes cause tsunamis when the movement of the seafloor is enough to move large amounts of water. Worldwide Plate Boundaries. There is no land originally, but a chain of island arcs builds up as volcanism develops above the subduction zone. The Japanese archipelago is located in an area where several continental and oceanic plates meet. Why Japan have so many earthquakes? Required fields are marked *. For those of you who have not yet heard, there has recently been an enormous Magnitude 8.9 earthquake and an accompanying tsunami in Japan. Well, any place where tectonic plates move past one another will occasionally experience earthshaking. They often ask if there’s a particular earthquake season like there is for tornadoes and hurricanes. Japan accounts for around 20 per cent of earthquakes around the … The country experiences around 1,500 shocks a year, including one or more in magnitude 6.5 or higher. In the confusion, Kamakura Shogun Hojo Sadatoki attacked his rival Taira no Yoritsuna, killing him and 90 of his followers. So, when thinking about whether or not a rock will become molten, you need to think about both temperature and pressure. This is the best overall explanation and best graphics I've seen of these issues and forces. That means that more powerful earthquakes are less likely to happen while less powerful ones are more likely. If you pay attention to the news, you probably know the large effect earthquakes have on Japan. At about 4.5 on the scale, earthquakes begin to become significant. These range from minor tremors to major destructive events like the 2011 Tohoku earthquake and tsunami which killed 15,899 people and caused $360-billion-worth of damages, making it the costliest natural disaster in human history. Once down, the water is released from the ocean floor into the surrounding rocks and melts them. Above this line, the mantle starts to melt. The most recent earthquake struck the Kumamoto region on Japan's Kyushu Island early Saturday, April 16 at 1:25 a.m. local time (12:25 p.m. This happens when one plate, usually a denser sea plate, goes under another, often a less-dense continental plate. In Japan alone, there are around 265 volcanoes classified as potentially active. Japan’s specific location in this “ring”, … This molten rock is less dense than the surrounding solid rock, so it flows upward to the surface. Figure taken from. Here are a couple of images showing subduction: When an oceanic plate subducts underneath a continental plate, this produces volcanism on the continent, such as the volcanism that occurs in the Western US in the Cascades. CNN has converted these to Pacific Standard Time estimates. Plate tectonics stretched out the Eurasian plate and pulled what is now Japan away from China and up to form islands. Instead, we know that the land that forms Japan was once attached to the eastern part of Eurasia in what is present-day China. This is the cause of frequent earthquakes and the presence of many volcanoes and hot springs across Japan. This reason is that Japan is located along the Pacific 'ring of fire' which is an area along the Pacific plate boundaries where there is a lot of volcanic activity (see below). Update: Dave Dudish- if your not going to help go away :L. Answer Save. It turns out, if you add water, carbon dioxide, or another volatile to a rock, it will melt at a much lower temperature than normal. The answer has to do with Japan's location. This makes them random on a human time scale and mostly impossible to predict with our current technology. Below is a map of estimated tsunami travel times. The abundance of volcanoes and earthquakes along the Ring of Fire is caused by the amount of movement of tectonic plates in the area. Earthquakes and Japan are almost synonymous. Plate tectonics, from Greek "builder" or "mason", is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere. Japan has earthquakes and volcanoes because the Pacific and Philipines plates underneath the Eurasian platesare losing water to the mantle rocks as they go down. interesting to read your explanation of the effects on rocks caused by the introduction of volatiles such as carbon dioxide and water – are you aware whether there have been any geological drilling expeditions off the east-coast of honshu island which could have flooded the fault-zone with either of these compounds and which, as a result, could have triggered the earthquake? As a quick reminder for those of you who are a little rusty on Geology 101, a volcanic island arc is a place where volcanoes are produced above a subduction zone. Of course, with such gradual and incremental processes, it’s impossible to pinpoint an exact moment when the landmass we know as Japan was born. The Ring of Fire extends in a horseshoe shape for 40,000 km (25,000 miles) and contains 75% of the world’s volcanoes and 90% of the world’s earthquakes. When the subducting plate is heated as it plunges into the hot, deep mantle, these volatiles are released and travel upwards since they are buoyant. Why Japan has so Many Earthquakes. Think about it like that: melting pure water ice requires 0 °C and melting pure table salt requires more than 800 °C. These same processes of plate tectonics are what cause the many geological phenomena in and around Japan. In fact, it has roughly 1,500 earthquakes each year. The earthquake was a major global event, and damage to the Fukushima Daiichi nuclear plant caused three nuclear meltdowns and release of radioactive contaminants that injured a number of workers and ultimately killed one via radiation exposure. Volcanoes, earthquakes, tsunamis - natural disasters have been occurring continuously since the beginning of the year, causing a lot of damage both human and material. There are currently tsunami warnings for the Pacific, so if you live on the West coast of the US or anywhere in the Pacific Ocean, please be cautious. It would also explain the abundance of hot springs in Japan. Here is a figure showing that Japan is part of a greater subduction zone called the Pacific “Ring of Fire”: But why is there volcanism above a subduction zone? If earthquakes occur below or close to the ocean, they may trigger tidal waves (tsunami). Rocks tend to lose heat very slowly, so if they are brought upwards quickly enough they won’t have time to cool down. Click to view larger. Earthquakes are most frequent where two or more plates meet. Though they move slowly, just 3-5 centimeters per year, their enormous size gives them incredible force, momentum and power. The result is an arc shape where the plate dips down before lifting up. Figure taken from, Three tectonic plates in Japan. Hot-spot volcanoes form rather simply: a thermal anomaly deep in the Earth causes rocks to heat up and melt. Knowing this, you can get a sense of the incredible power released by the 2011 Tohoku Earthquake that rated a 9.0. The same principle works in the deep Earth. Why does Japan have so many Volcanoes? When an oceanic plate subducts underneath another oceanic plate, a volcanic island arc is formed. We do shake in Japan….a lot. These islands slowly grew and merged into the much larger islands that make up Japan. Many parts of the country have experienced devastating earthquakes and tidal waves in the past. Also, it is fomed on the volcanic line, called "Ring of Fire. If you are planning for a visit, you should know why the country experiences so many earthquakes and how the government and people deal with this natural hazard. 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