What causes an earthquake? | Natural Disasters

Summary

This video explains the dynamics of Earth's tectonic plates, which are constantly moving and interacting. It describes various plate boundaries: rifting occurs when plates drift apart, subduction happens when oceanic plates slip under others, and mountains form when continental plates collide. The video also covers conservative boundaries where plates slide past each other. The immense friction between plates can cause earthquakes, with larger ones occurring at subduction zones. Notable examples include the 2004 Sumatra earthquake. The movement of these plates averages about 4 cm per year, similar to the rate of fingernail growth.

Takeaways

• 🌍 The Earth's surface consists of around 15 tectonic plates that are constantly moving.
• 🌊 Some parts of the plates consist of continents, while others consist of oceans.
• 🌋 Where plates meet is called a plate boundary, and these areas are filled with fault lines and cracks.
• 🕳️ Plates can drift apart, leading to rifting, where new oceanic crust forms as lava erupts from the surface.
• 🌪️ When oceanic plates collide, subduction occurs, where one plate slips under the other into the Earth's mantle.
• 🏔️ Continental plates are thicker and more buoyant, so when they collide, they push upwards, forming mountains like the Himalayas.
• 🌀 Some plates slide past each other at conservative plate boundaries, causing friction but no vertical movement.
• 🐢 Tectonic plates move at an average rate of 4 cm per year, similar to the growth of human fingernails.
• 💥 High friction between tectonic plates causes pressure to build, eventually leading to sudden and violent movements, resulting in earthquakes.
• 🌊 The largest earthquakes, like the 2004 Sumatra earthquake, happen at subduction zones, sometimes with fault lines stretching over 1,300 km and causing massive tsunamis.

Q & A

What are tectonic plates?

Tectonic plates are large slabs of the Earth's crust that move and interact with each other, forming the surface of the Earth. Some plates consist of continents, while others are composed of oceans.

What is a plate boundary?

A plate boundary is the location where two tectonic plates meet. These boundaries are zones of intense fracturing and are often riddled with cracks called fault lines.

What happens when plates drift away from each other?

When plates drift away from each other, the crust can become thin and break, leading to volcanic eruptions that create new oceanic crust. This process is known as rifting.

What is subduction?

Subduction occurs when an oceanic plate is pushed under another plate and absorbed into the Earth's mantle. This usually happens when oceanic crust collides with another plate.

Why do continental plates not subduct like oceanic plates?

Continental plates are thicker and more buoyant than oceanic plates, making it impossible for them to slip under each other. When they collide, they are pushed upward, forming mountain ranges like the Himalayas.

What is a conservative plate boundary?

A conservative plate boundary is where two tectonic plates slide past each other without colliding or drifting apart. This type of movement can cause earthquakes.

How fast do tectonic plates move?

Tectonic plates move at an average rate of about 4 centimeters per year, which is approximately the speed at which human fingernails grow.

What causes earthquakes at fault lines?

Earthquakes occur when the friction between two slabs of rock along a fault line is overcome by pressure, causing the plates to move suddenly and violently.

What determines the magnitude of an earthquake?

The magnitude of an earthquake is determined by the size of the fault and the distance the slabs of rock move when the plates finally shift.

Where do the largest earthquakes typically occur?

The largest earthquakes usually occur at subduction plate boundaries, where oceanic plates slip under other plates. An example is the 2004 Sumatra earthquake, which had a magnitude of 9.1.