Subtitles section Play video Print subtitles A 7.8 magnitude Earthquake rained avalanches on Mount Everest and devastated Nepal. What exactly is going on underground when the Earth moves so violently? The Theory of Plate tectonics was put forward in the mid-20th century based on decades of earlier research. One scientist, Alfred Wegener first suggested the concept of continental drift in 1912 - the idea that land masses can move across the earth’s surfaces. But he didn’t know the mechanism behind the movement. Throughout the 50s, 60s and 70s more pieces of the puzzle fell into place. Including ideas like sea-floor spreading, and global crustal motion. Now scientists know that the Earth is made up of several layers, the mantle and the crust make up the outermost shell, the Lithosphere. This crust is broken up into 7 or 8 major tectonic plates which float on top of another layer called the asthenosphere. The molten rock beneath them move them around like a conveyer belt. Sometimes the plates meet up and move towards each other forming a convergent boundary, when they move apart, it’s a divergent boundary, when they slide past each other it’s a transform. When plates slide over, under or past each other it creates a lot of pressure which can be released as a volcanic eruption or an Earthquake. Nepal sits on a volatile zone. The Indian plate broke off from Madagascar 90 million years ago. Around 50 million years ago it hit the Eurasian plate. This forced the Indian plate to take a dive, while the other plate thrusted upwards creating the Himalayas. When two plates meet like this, it’s called a thrust fault. Millions of years later, they’re still crashing into each other. The Indian plate subducts, or is sliding beneath the other plate, and moves North 2 inches (5 centimeters) a year. This builds up enormous amounts of pressure. When all that pressure is released, it can mean disaster. This region is weirdly used to earthquakes, for some reason. They seem to experience large quakes every 75 years or so, like clockwork. And this one was right on cue, the last major Earthquake struck in 1934. But this recent earthquake was shallow, at only 15 kilometres deep. While a 7 magnitude earthquake is devastating on its own, a shallow depth means more shaking at the surface and more damage. At the time of this taping, the death toll from this catastrophic earthquake’s death toll is over 4-thousand and is expected to rise. Buildings, temples and homes have been toppled as many remain in need of help. Recovery efforts are underway with aid and humanitarian organizations mobilizing to provide much needed support, but they need help. In response to the tragic earthquake, Discovery Communications will be making a $250,000 donation to relief efforts. And we hope that you too can support the people of Nepal by visiting GlobalGiving’s Nepal Earthquake Relief Fund page. We’ve got a link below in the description. Thanks for watching DNews.