That's why you're seeing in this diagram that there's no real bands on here sort of holding all the bits together. We don't know much about the subduction zones.
So. Megathrust faults. They also crop up in subduction zones— where one tectonic plate dives beneath another. That’s what’s happening at the Cascadia Subduction Zone, a 1,300-kilometer-long tectonic plate boundary that runs along the United States’ Northwest Pacific Coast. Here, the Juan de Fuca and Gorda oceanic plates are subducting beneath the North American continental plate, creating a megathrust fault in between.
Here, the Juan de Fuca and Gorda oceanic plates are subducting beneath the North American continental plate, creating a megathrust fault in between. In the last 3,500 years, the Cascadia Subduction Zone has generated at least seven major earthquakes, occurring 246 years apart on average. The oral histories of the Huu-ay-aht and Cowichan First Nations describe an earthquake triggering landslides and fifty-foot waves, wiping out whole villages, and leaving ghost forests in its wake.
Many volcanic eruptions happen at plate boundaries: places where the tectonic plates that make up Earth’s outermost layer squish together or spread apart. Like, lots of volcanoes form at subduction zones, where two tectonic plates converge. One gets forced beneath the other and back into the mantle.
In 2015, a 7.8-magnitude quake occurred on this fault in Kathmandu, Nepal, killing nine thousand people and injuring many more. So. Megathrust faults. They also crop up in subduction zones— where one tectonic plate dives beneath another. That’s what’s happening at the Cascadia Subduction Zone, a 1,300-kilometer-long tectonic plate boundary that runs along the United States’ Northwest Pacific Coast.
And sometimes, institutions that have the resources for earthquake preparedness simply don’t take advantage of them. In 2015, journalist Kathryn Schulz investigated the risks of a massive earthquake in the Cascadia subduction zone. Her report was staggering: For one thing, the region didn’t have an early warning system at the time.
Meanwhile, at convergent boundaries, plates move toward each other. When a dense oceanic plate meets a more buoyant continental plate, a process called subduction happens: the denser plate slides underneath the other one, returning that rock to the mantle. This is primarily thanks to slab pull: the gravitational force that yanks plates downward.
This is primarily thanks to slab pull: the gravitational force that yanks plates downward. And this is largely what happens in the Ring of Fire; it’s full of subduction zones. As the oceanic plates slide deep underground, they release water into the hot rocks above, which has an explosive result.
That's why you're seeing in this diagram that there's no real bands on here sort of holding all the bits together. 200 million years later it's disappearing into the deep trenches, the subduction zone.
That water can cause the overlying rocks to melt, driving tons of volcanic activity. And if two dense, oceanic plates meet at a convergent boundary, subduction can create huge depressions in the surface, like the Ring of Fire’s Mariana Trench, which contains the deepest point in the world!
That’s what’s happening at the Cascadia Subduction Zone, a 1,300-kilometer-long tectonic plate boundary that runs along the United States’ Northwest Pacific Coast. Here, the Juan de Fuca and Gorda oceanic plates are subducting beneath the North American continental plate, creating a megathrust fault in between. In the last 3,500 years, the Cascadia Subduction Zone has generated at least seven major earthquakes, occurring 246 years apart on average.