Tectonic plates have been responsible for everything from entire cities going under to beautiful mountain ranges going up. Here are six things you should know about them.

The Definition

First, let’s cover the most basic thing you should know, which is what a tectonic plate is. A tectonic plate is a massive slab of solid rock that can vary greatly in size. These plates sit below the Earth’s surface and can reside below both the ocean and continental areas.

How Big Are They?

Again, they differ a lot in size. Some are less than a 1,000 feet long. Others are miles. The Antarctic and Pacific plates are the largest, though. Their thickness varies by about the same degree, too. The thickest are a little over 120 miles.

They Move

Despite their gigantic size, tectonic plates move, albeit quite slowly. It’s because of the fact that we can see how some of them would fit together that we know that what we call continents today were all attached at one time. The movements of these giant plates slowly separated them.

The reason they move is because our planet’s lithosphere is far stronger than the asthenosphere.

They Move Extremely Slowly

As we mentioned before, though, their movements are imperceptivity slow. The slowest clocks in at just 40 mm/year. That would be the Mid-Atlantic Ridge and its movement would be as fast as your fingernail grows.

The speed demon of the group is the Nazca Plate. It moves about as fast as your hair grows, a blazing 160 mm/year.

They Have Boundaries

These are the areas where two plates meet. Given all the moving they do, this changes over time. Obviously, it takes a very, very, very long time for this to change, though. There can be three types of boundaries depending on how they meet: convergent, transform or divergent.

Plate Boundaries Are Dangerous

You’re probably already aware that tectonic plates can cause earthquakes, big and small. They have even caused topographic features like mid-ocean ridges, volcanoes, oceanic trenches and even entire mountains.

However, it’s earthquakes that they have become best known for and understandably so. Areas that exist above these plates are the ones most likely to experience earthquakes.

Active volcanoes tend to occur along tectonic plate boundaries, too. The Ring of Fire located along the Pacific Plate is the world’s most active.

Tectonic plates have been shaping our world since long before we were here to record any of it. Given their unimaginable size and power, scientists do their best to track these plates in an effort to predict when the next earthquake may occur.