Unit 2: Tectonic Processes Ms. Thind
What is an earthquake? Caused by shifting of the earth’s crust Occur when plates or rock within the earth suddenly break or shift under stress
Most common at convergent, subduction, and transform boundaries Continent to continent eg: Indian vs Eurasian plate = Kashmir 2005 Subduction of plate eg: Nazca Plate subducting at SA plate = 1970 Peru Transform (sliding of plates) eg: Pacific Plate sliding past the San Andreas Fault on NA plate = 1989 San Fran Where do earthquakes occur?
The shaking and damage produced by earthquakes is due to 2 types of shock waves: 1. Body Wave : travels through the interior of the earth. Subdivided into: 1) P Wave: Primary waves travel at high velocity and through material in any form (solid, liquid, gas) 2) S Wave: Secondary waves travel at 60% of P Body Waves and through solids only Seismic Waves
2. Surface Wave: travels through the thin outer layer of the crust. Subdivided into: 1) Rayleigh Waves: slow waves that travel as ripples = ground moving up and down 2) Love Waves: slow waves that travel in a circular motion = ground move left and right a4
Seismic waves generate from the epicenter: the point where the earthquake originates. Next class: how we measure earthquakes and how earthquakes have devastating effects Seismic Waves cont…