When we think of tectonic plates, we often imagine them crashing together to build mountains or pulling apart to create oceans. However, some of the most dramatic geological events happen when plates simply try to slide past one another. These are called transform plate boundaries, and they are responsible for some of the most powerful earthquakes.
In this blog post, we’ll explore the buildup and release of stress along these boundaries and explain why it causes sudden, powerful earthquakes.
Unlike other plate boundaries, transform boundaries don’t create or destroy crust. Instead, they involve two huge slabs of rock sliding past each other.
This movement is triggered by convection currents deep within the Earth. As these currents move, the plates above are pushed horizontally. However, since the edges of tectonic plates are jagged and made of solid rock, they don't exactly glide. They grind.
As the transform plates push past each other, they create shearing forces. For example, if you slide two pieces of very coarse sandpaper against each other, the rough edges catch and resist movement.
In geological terms, the plates can become locked. While the edges remain stuck, the rest of the plate continues to push. This causes the rocks to bend and store energy like a coiled spring.
So, how do we get from a stuck plate to a shaking ground? The answer is at the breaking point.
When the pressure from those shearing forces finally overcomes the friction holding the rocks together, the plates shift abruptly. This sudden movement causes earthquakes.
The energy isn't released slowly. Instead, it bursts out in seismic waves. To better understand this, we can look at an earthquake diagram below.
The point underground where the snap happens is the focus, and the spot directly above it on the surface is the epicentre.
Since transform boundaries occur at the surface of the crust, the focus is usually quite shallow. This is an important bit of information because the closer the focus is to the surface, the more energy it releases, which leads to more intense shaking.
For a clear, step-by-step visual of this process, the team at HRB Education has put together a fantastic short video that explains the cycle of friction and release:
Watch: Transform Plate Boundaries: How do Earthquakes Occur | GCSE Geography Help
When we talk about the primary effects of earthquakes, we focus on the immediate physical damage caused by ground movement.
At a transform boundary, this looks like:
To help you revise for your GCSEs, we’ve listed some facts about earthquakes below. Check them out.
Understanding the friction and flow of the Earth’s crust is an important part of the GCSE curriculum, but it’s easy to get lost in the terminology. At HRB Education, we believe that geography should be about understanding the world around us, not just memorising what is an earthquake.
Our tuition and homeschooling services are designed to help students connect the dots between the theory in their textbooks and the real-world forces that shape our landscape.
Schedule a call with us to learn more about our services.
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