字幕表 動画を再生する 英語字幕をプリント "Offer a magnificent view of nature's greatest power display." Mount Mayon in the Philippines erupted in January. It continued for over a month. In February, Mount Sinabung erupted in Indonesia. Here's the ash cloud as seen from space. And in June an eruption in Guatemala killed more than 100 people. Turns out this is pretty normal. On average, there are 10 to 20 volcanoes erupting around the world at any given time. When you look at these on a map and add volcanoes that are not currently erupting, you'll start to see a pattern. Most are concentrated here, along the edges of the Pacific Ocean. This region is known as the Ring of Fire, a stretch of hundreds of volcanoes spanning 40,000 kilometers. It's also where most of the earthquakes and tsunamis in the world take place. This year alone, the region saw 4 eruptions and 5 of the world's biggest earthquakes . The Ring of Fire is where some of history's most devastating natural disasters have happened and will continue to happen. "There are still some volcanoes around the world in various places. Do you know where they are? Here's a map, see if you can find some." Volcanoes have terrorized people for centuries. In the 1800s, explorers and scientists started grouping them together. Take a look at this map from 1852. It has “the volcanic series of Australia”. And "the volcanic series of Japan and Kamchatka, in Russia." In fact, the whole Ring of Fire is marked here. Scientists recognized the belt of activity, but it would take another 100 years until they agreed on what caused it. "That's right, it's a volcano. Well, you see what you and I are going to talk about today is the world under our feet." By the 1960s, most scientists concluded the earth's surface is made up of a series of tectonic plates that slowly move into and apart from each other. Take a look at the plates that make up the Pacific. Now look at where the eruptions and earthquakes occur. The Ring of Fire is the result of these plates crashing into each other. "One in Japan, that's right. Fujiyama. There's some others in the south Pacific. How about in our part of the world?" "Mexico." "That's right, there's several in Mexico." The plates in the Pacific are moving faster than other plates around the world, adding stress where the plates interact. This plate is moving northwest, crashing into the North American plate, which explains all the volcanoes here. Over in California, the Pacific plate is grinding past the North American Plate -- where they meet is called the San Andreas Fault. The movement causes thousands of earthquakes a year. A few of them are even large enough to cause serious damage. Like the San Francisco-Oakland earthquake in 1989, which killed 63 people and injured nearly 4,000. All these plate interactions are independent from each other. But when grouped together, they make up the most seismically active region in the world. "Remember a little while ago an island blew up and disappeared?" "Oh yeah." "That was because of a volcano." The problem with the Ring of Fire is that geologists can't accurately predict when a volcano is going to erupt or an earthquake will shake the ground. They can monitor tremors, gas emissions and temperature changes around a volcano to estimate when it might erupt, but they can't be sure of the exact timing or the severity. And those predictions get even weaker with earthquakes which aren't preceded by any warning signs, so we can't even see them coming. One way scientists forecast the future of these phenomena is by looking at the past -- take New Zealand for example: Earthquakes have occured on this fault line every 500 to 1,000 years. There was a massive quake over 800 years ago and another one around the 500 mark. So scientists now believe New Zealand is due for mega quake. Over here in California, there is a 72% chance of a major earthquake along northern section of the San Andreas faultline in the next 30 years. Parts of Japan have a 25% chance of a big quake and Seattle could see one in the next 50 years that could impact 7 million people. In fact many countries along the Ring of Fire will continue to be at risk for the foreseeable future. They can't get out of harm's way, but there is something they can do about it. In 2011, an earthquake and a following tsunami, killed 15,000 people and caused $300 billion in damages in Japan. But those numbers could've been a lot higher. See, Japan requires buildings be constructed with anti-earthquake designs, like the one in this video. And it has an early warning system that stopped high-speed trains, factory lines, and sent countrywide text alerts a full minute before the tremor hit. While Japan's precautions didn't prevent the disaster, they did save countless lives. The problem is, not every country in the Ring of Fire is like Japan. Most of these countries have some form of anti-earthquake building code, but the quality and implementation of these codes varies. And none of these countries have early warning systems for earthquakes. In developing countries, funding these projects can be a problem. But even richer countries aren't taking the risk seriously enough. California, Oregon, Washington. Some of the most vulnerable states in the US, still don't have a public early-warning system in place. Because volcanoes and earthquakes continue to be unpredictable threats, governments tend to treat them as a low priority. And that's what makes the Ring of Fire even more dangerous. We know for certain that there will be more natural disasters along this belt. What we don't know is if we'll be prepared for them. "Future studies will surely improve the clarity with which scientists view the interior of the Earth and will help people accomodate their activities to these powerful, sometimes destructive, often beneficial, always fascinating neighbors.
B1 中級 米 太平洋を中心に自然災害が輪をかけている理由 (Why there's a ring of natural disasters around the Pacific) 192 5 Amy.Lin に公開 2021 年 01 月 14 日 シェア シェア 保存 報告 動画の中の単語