EOSC 114 Earthquakes.docx

EOSC 114: Earthquakes Learning Goals 1. Describe the global distribution of - globally, earthquakes located mostly on earthquakes and how often quakes of various tectonic plate boundaries magnitudes occur - higher frequency = lower magnitude; higher magnitude = lower frequency 2. Understand the different types of faulting at Plate boundaries+ Faults: different plate boundaries, and which plate 1. Divergent: Plates move apart at mid-ocean boundaries produce the largest quakes ridges & spreading centressmall earthquakes  normal dip-slip faults 2. Transform: Plates slide beside each other (shearing) many medium-large earthquakes strike-slip faults 3. Convergent Type 1: Plates collide, causing compression. One plate is more dense and subducts under other small to largest earthquakes (at subduction zone) reverse dip-slip faults 4. Convergent Type 2: Plates collide, causing compression. Neither subducts so crumple, form mountains  small to large earthquakes reverse dip-slip faults 3. Describe how the Earth builds, stores, and Constant movement of tectonic plates over releases energy in earthquakes (elastic many years builds pressure, storing PE. rebound) Increased stress breaking, so too much stress causes a slip, releasing energy in an elastic form (reverting to original form) 4. Understand concepts of (1) stress causing 1. Stress is force/unit area, while strain is how strain and (2) plastic versus brittle deformation material changes shape from stress. ie.strain is change in shape due to stress 2. Plastic deformation is permanent change, ie. hammering gold sheets. Brittle is breakage, does not hold plastic shape well, ie. hammering glass plate 5. Describe how the rupture propagates from the focus and why shaking and damage are not necessarily greatest at the epicenter 6. Describe the different types of seismic 1. Body Waves: travel in earth (faster than waves and how they move through the Earth surface waves) in curved pathways (refracted due to earth layers) a) P-wave (primary) particles move back & forth in direction wave is travelling (ex. slinky) b) S-wave (secondary)  particles move vertically perpendicular to direction wave is travelling (ex. up&down snake); can’t travel through liquids/water 2. Surface Waves: travel on surface of earth (slower, more damaging than body waves) a) Rayleigh Waveslargest, most damaging; particles rotate backwards, counter clockwise (like ocean) EOSC 114: Earthquakes Learning Goals b) Love waves: particles move horizontally perpendicular to surface (slithering snake) 7. Understand the principle behind early warning systems (such as the one in Japan) and how much warning time they can give 8. Describe how an earthquake is recorded -Mainly relative arrival times b/w P-waves and and how to locate the epicenter