Understanding Earthquakes and Plate Tectonics

Focus

The location of the slippage underground.

Epicenter

The point on the Earth's surface above the focus.

Crust

Consists of large slabs that move on the upper mantle.

Upper Mantle

Its convection currents drive the movement of the crust.

Earthquakes

Occur when tectonic plates create friction at their boundaries, and the built-up stress is released, causing vibrations.

Elastic Rebound

The process where rock snaps back after the built-up stress is released.

Body Waves

Waves that move through Earth's interior (P and S waves).

Surface Waves

Waves that move along the surface (Rayleigh and Love waves).

P Waves

Faster waves that travel through solids, liquids, and gases.

S Waves

Slower waves that only travel through solids.

Converging Boundaries

Where plates move toward each other, and one sinks beneath the other, forming a subduction zone.

Diverging Boundaries

Where plates move apart, forming rift valleys on land and mid-ocean ridges or volcanic islands underwater.

Magnitude

Measures energy released (quantitative, from seismograms).

Intensity

Measures shaking and damage (qualitative, based on observations).