BBC Earth - Plate tectonics explained many geology puzzles Volcanoes and earthquakes: The Pacific Ring of Fire is very active this week A massive column of smoke and ash shot nearly 10 miles into the sky above Sumatra Monday morning as Mount Sinabung, one of three currently active volcanoes in Indonesia, began erupting. It’s the latest rumble in what’s already been a very rowdy couple of months along the Ring of Fire, the geological region that follows the 25,000-mile perimeter of the Pacific Ocean and is home to 90 percent of the world’s earthquakes. The Volcanic Ash Advisory Center in Australia warned aircraft to divert from Sumatra, but noted that satellite imagery shows that much of the ash has already dissipated. Mount Sinabung has a tragic history, with deadly eruptions in 2010, 2014, and 2016. Over in the Philippines, Mount Mayon, which began erupting on January 13 and forced 75,000 to flee, saw another eruption of ash and lava on Monday. Mount Kusatsu-Shirane, 100 miles northwest of Tokyo, also erupted in January, leaving one soldier dead in an avalanche and injuring a dozen at a ski resort.
The Geological Society Skip Intro >> Background image: The weathered slopes of Snowdonia Choose a new background: 1 2 3 4 5 6 7 8 What is Plate Tectonics? | Plate Tectonics From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth's surface in the present and the past. Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core. The plates act like a hard and rigid shell compared to Earth's mantle. This strong outer layer is called the lithosphere, which is 100 km (60 miles) thick, according to Encyclopedia Britannica. The lithosphere includes the crust and outer part of the mantle. Below the lithosphere is the asthenosphere, which is malleable or partially malleable, allowing the lithosphere to move around. Developed from the 1950s through the 1970s, plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912. There are nine major plates, according to World Atlas. There are also many smaller plates throughout the world. Additional resources
What is Plate Tectonics? | Plate Tectonics From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth's surface in the present and the past. Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core. The plates act like a hard and rigid shell compared to Earth's mantle. This strong outer layer is called the lithosphere. Developed from the 1950s through the 1970s, plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912. "Before plate tectonics, people had to come up with explanations of the geologic features in their region that were unique to that particular region," Van der Elst said. The driving force behind plate tectonics is convection in the mantle. Mid-ocean ridges are gaps between tectonic plates that mantle the Earth like seams on a baseball.