GEOL 240Lg 1st Edition Lecture 8Outline of Last Lecture I. The three principle stressesII. Definition of total stressIII. Maximum Compressive StressIV. Normal Fault V. Reverse FaultsVI. Strike- Slip FaultsVII. Principal stress planes VIII. Thrust PlanesOutline Current Lecture I. Review Stresses II. Plate tectonicIII. Elastic Rebound TheoryIV. Energy in rocksV. States with major earthquakes Current LectureWhat is the orientation of sigma 3? Horizontal- Sigma 2 vertical - Plate tectonic Energy causes tectonic stresses that causes earthquakes - Elastic Rebound Theory: explains in detail where the energy comes from that are responsible for generating earthquakes?- Elastic strain energy professor is demonstrating with a long stick and bending it and pushing against his fingers, he said it pushes back against your finger. - Professor is pretending to bend a rock. He explains that rock shares elasticity so when hebends it the rock actually does bend, slightly. This means that that rock and rocks underneath are feet are atoms and many more bending which disturbs - Professor is pulling the rubber band and he says he is “winding the clock” therefore storing more energy to it. “Rocks are elastic” we bend the rocks because the plates are moving… causes an enormous amount of energy.One of the all-time great earthquake photos: - 2010 Greendale- Present Configuration of the Pacific- North American plate boundary- Major western cities at seismic risk- LA- thrust, strike- slip faulting- San Diego- Strike-slip faultingSeattle WA- Subduction earthquakes, thrust faulting- Mount St Helens 1980 Eruption: landslide followed by blast due to pressure releaseExplosion caused by the gasses trapped magma being clogged - North-south crustal shortening in WA has produced E-W folds in the south-central state (below) - We want to focus on the Seattle area- Bainbridge Island : LIDAR - GPS: Global positional system - Who paid for the GPS satellite department: military usage, designed originally for military usage When two plates converge towards each other and if the interface between them is locked.. the upper plate must ….( blackboard)- Measurements of coastal uplift from the southern part of Vancouver slide - JAN 26, 1700 around 9ish- During an earthquake, all the energy that has been stored up by the
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