Earth's Layers and Plate Tectonics

Study Notes

Earth's Layers

Earth is divided into three layers: crust, mantle, and core.
The crust is the outermost solid layer, housing all living things.
The mantle is below the crust, with the asthenosphere (upper mantle) being a partially molten layer responsible for tectonic plate movement.
The core is the Earth's innermost layer, with the inner core being the hottest.
Lithosphere is the rigid outermost layer of Earth, composed of the crust and upper mantle.

Plate Tectonics

The Earth's surface is made up of large plates called tectonic plates.
The movement of these plates along faults causes earthquakes.
There are three types of tectonic plate boundaries:
- Divergent boundaries: Plates move apart, creating ridges, volcanoes, earthquakes, and new crust.
- Convergent boundaries: Plates collide, forming mountains, volcanoes, trenches, and earthquakes.
- Transform boundaries: Plates slide past each other, causing earthquakes, fault lines, and scarps.

Earthquakes

Earthquakes occur due to the movement of tectonic plates along faults.
Focus (Hypocenter): The point underground where the earthquake rupture starts.
Epicenter: The point on Earth's surface directly above the focus, where the strongest shaking is felt.
Earthquakes are measured by their magnitude (strength) using the Richter scale.
Earthquakes are also described by their intensity (damage), measured using the Modified Mercalli Intensity (MMI) Scale.
Seismograph/Seismometer: An instrument that measures and records seismic waves.

Types of Faults

Faults are fractures in the Earth's crust.
Reverse fault: A fault where one rock mass is pushed upwards relative to the other.
Normal fault: A fault where one rock mass is pushed downwards relative to the other.
Transform fault: A fault where rock masses slide past each other horizontally.

Seismic Waves

Seismic waves are vibrations that travel through Earth during an earthquake.
Body waves: Travel through the interior of Earth.
- P-waves (Primary waves): Compress rocks and travel through all states of matter.
- S-waves (Secondary waves): Displace rocks and cannot travel through liquids.
Surface waves: Travel along the surface of Earth.
- Rayleigh waves: Travel along the surface, causing up-and-down motion, and are the most destructive.
- Love waves: Travel horizontally, causing side-to-side shaking.

Earthquake Safety

Drop, Cover, Hold On: During an earthquake, drop to the ground, cover your head and neck, and hold on to something sturdy.
If outdoors, move away from buildings, trees, streetlights, and power lines.
Be prepared with an earthquake kit.

Description

Explore the intricate structure of Earth's layers, including the crust, mantle, and core. Understand how tectonic plates interact at their boundaries, leading to natural phenomena like earthquakes and volcanic activity. This quiz covers key concepts in geology, providing insights into the dynamics of our planet.