Earthquakes Earth shaking Basic Earthquake Words The epicenter

Earthquakes Earth shaking

Basic Earthquake Words: The epicenter and focus An Earthquake is the group of waves that spread away from the focus Force pushing Fault is a crack That forms Along the break

Earthquakes require a brittle-solid that breaks – the lithosphere - force builds but no shape changing shape, not plastic - break/shatters when force large enough - Earth material (rock) goes twang, energy released Lithosphere: as earthquake waves (plate) brittle solid, strong earthquakes Mantle: plastic – oozes Outer Core: liquid Inner Core: solid

Earthquakes are concentrated around plate boundaries Depth of Focus: 0 -70 km 70 -300 km 300 -700 km Plates

Earthquakes Exist In the Form of Waves: Most expressed are P & S • Pressure, Primary (P) waves: - squeeze - slinky push-pull - faster than sideways wave in Earth - travels through solids and liquids - Ex: sound only pressure wave • Sideways, Secondary (S) waves: - rope wiggle - slower than pressure wave in Earth - travels through solids, NOT liquids • Solids transmit P and S waves - Sudden force in a solid makes P and S together, usually cannot separate - Example: smack board with hammer (Garrison, 1993)

Actually, there are three types of Earthquake waves P=Pressure wave Slinky push-pull, Caterpillar scrunch Fastest, 1 st to arrive S=Shear wave Sideways wiggle Slinky sideways wiggle Rope wiggle Slower, 2 nd to arrive Surface Wave Only travels on a surface, Maximum movement on surface, Movement decreases away from surface, Movement disappears far enough away from surface Slowest, 3 rd to arrive Causes Most of the Damage 2 Flavors Of Surface waves

An earthquake in lithosphere (plate) makes P, S and Surface waves that spread outward in all directions Surface Waves Only travel On the surface If the Earth were uniform, stronger P and S waves would travel inside in straight lines through the entire Earth. = focus