字幕表 動画を再生する 英語字幕をプリント You're trying to sleep. But it's kinda hot in here so you get up to grab a fan. But how can you get out of bed when... the floor is lava! There are several different types of lava, but they all come from the same place. Before it becomes lava, it's called magma, which is thick molten rock flowing under the Earth's crust. Once it erupts, and finds its way above ground, it's then known as lava. Lava flows are the most common volcanic feature on the planet. They cover about 70% of the Earth. And soon, you'll know how to walk on them. Lava flows can be unbelievably hot, and incredibly unpredictable. At the rim of a volcano, the temperature will be around 500 °C (932 °F). So don't stay too long on the lava. Get your thrills, and go relax somewhere that's cool and safe. You're going to want a suit and shoes made of Kevlar® material. Kevlar® is heat resistant, it can be made 8 to 9 times stronger than steel, and it's used for some really cool stuff. Like stopping bullets. And volcanoes, but only up to 426 °C (800 °F). You'll be breathing in huge amounts of sulfur, methane, carbon monoxide, and ammonia. Wear a mask to protect yourself against all the toxic volcanic gases. Get one with a sulfur dioxide scrubber cartridge for the best protection. If you still choose to go through with this stunt, you'll do more of a run across the lava than a walk. The temperature of lava is usually around 1,000 °C (1,832 °F), and at that heat, no suit would be able to protect you. If you imagined taking a nice stroll atop a lava flow, you probably wouldn't make it very far before catching fire. So if you're about to step on some lava, make sure you get a running start. While being able to take a few steps on a lava flow might make you feel cool and invincible, don't forget that volcanoes are a force to be reckoned with. Volcanoes kill 540 people each year on average, and a study by scientists from the University of Bristol shows that most fatalities occur within 10 km (6 mi) of a volcano. Really, the best way you can survive walking on lava is not to do it at all. But you can't always predict when disaster will strike, so it's good to be prepared. What should you do if you're suddenly trapped in a falling elevator? Find out next time on HOW TO SURVIVE.