Transcript Chapter 19
Chapter 19 Pg. 526 Earthquakes Vocabulary • Deformation- The bending, tilting, and breaking of Earth’s crust. • Stress- The total force acting on crustal rocks per unit of area. • Strain- The deformation of material in response to stress. • Fault- A fracture along which crust move. Movement- Pulled away from each other Boundary- Divergent Stress- Tension Fault- Normal Normal faults commonly form at divergent boundaries, where the crust is being pulled apart by tension. Movement- Push together Boundary- Convergent Stress- Compression Fault- Reverse Reverse faults normally form at convergent plate boundaries, where the crust is being pushed together by compression. Movement- Moves side-by-side Boundary- Transform Stress- Shear Fault- Strike-Slip Strike-slip faults normally occur along transform plate boundaries, where the crust is moving side-by-side by shear stress. How and Where Earthquake Happen oEarthquakes occur when rocks under stress suddenly shift along a fault. oVibration of Earth caused by the release of energy by the movement of the fault or plate. oAssociated with movements along faults and plate boundaries Vocabulary Focus- The exact point underground where the energy is released. Where the earthquake starts. Epicenter- The point of Earth’s surface directly above the focus. Primary (P) Wave • Primary waves are a type of body wave (travel inside Earth). • Primary waves are the fastest waves and are the first to reach seismic stations. • Push-pull motion (compressional waves) • Travels through solids, liquids, & gases Secondary (S) Wave • Secondary waves are a type of body wave (travel inside Earth). • Secondary waves are the 2nd fastest waves and are second to reach seismic stations. • “side-to-side” motion (sheer waves) • travels only through solids Love and Rayleigh Waves • Love and Rayleigh waves are a type of surface wave (travel on Earth’s surface). • Very destructive seismic waves. • Slow moving seismic waves • Love waves are surface waves that cause rock to move side-to-side and perpendicular to the direction of the wave. • Rayleigh waves are surface waves cause the ground to move with an elliptical, rolling motion.