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Earthquakes and Deformation of the Crust Earthquakes and Deformation of the Crust 1 Deformation of the Crust • Stress –Force that causes pressure in the rocks of the earth’s crust • Strain –Change in the shape or volume of rocks from stress Earthquakes and Deformation of the Crust 2 Rock Layers Experience shearing compression tension Earthquakes and Deformation of the Crust 3 Folding • When rock becomes permanently deformed without breaking –Anticline –Syncline –Monocline Earthquakes and Deformation of the Crust 4 Anticline • When rock layers are folded and uplifted into arch like patterns Earthquakes and Deformation of the Crust 5 Syncline • Downward folds like a bowl • Or sink Earthquakes and Deformation of the Crust 6 Monocline • Gently dipping fold in the rock layers Earthquakes and Deformation of the Crust 7 Faulting • Fault –Break in rock –Rocks on either side of the break move • Fracture –Break in rock with no movement. Earthquakes and Deformation of the Crust 8 Folds Vs. Faults Earthquakes and Deformation of the Crust 9 Footwall & Hanging Wall Earthquakes and Deformation of the Crust 10 Normal Fault • Fault plane is 45° or more • Hanging wall drops relative to the footwall • Divergent boundaries Earthquakes and Deformation of the Crust 11 Reverse Fault Fault plane is 45° • Hanging wall moves up relative to the footwall • Due to compression Earthquakes and Deformation of the Crust 12 Thrust Fault • Special kind of reverse fault • Fault angle is less than 45° Earthquakes and Deformation of the Crust 13 Strike Slip Earthquakes and Deformation of the Crust 14 Reverse Thrust Strike Slip Normal Blind Thrust Oblique Earthquakes and Deformation of the Crust 15 Mountain Formation • Smallest to Biggest –Mountain –Mountain range –Mountain system –Mountain belt Earthquakes and Deformation of the Crust 16 Mountain Belts • Evidence that mountains are created when lithospheric plates collide • Name some examples • Appalachians? –Formed where plates collided in the past Earthquakes and Deformation of the Crust 17 Folded Mountains • Formed when tectonic movements have squeezed the rock layers together like an accordion Earthquakes and Deformation of the Crust 18 Earthquakes and Deformation of the Crust 19 Fault Block Mountain • Formed when faulting breaks the Earth’s crust into large sections • The sections are uplifted and tilted Earthquakes and Deformation of the Crust 20 Earthquakes and Deformation of the Crust 21 Fault Block Mountain and Graben Earthquakes and Deformation of the Crust 22 Grabens • long narrow valley formed by faulting and downward slippage of a crustal block Earthquakes and Deformation of the Crust 23 Volcanic Mountains • Formed when molten rock erupts onto the earth’s surface • Earthquakes and Deformation of the Crust 24 Dome mountains • Created when molten rock pushes up rock layers on the Earth’s surface • Then the layers then are worn away in places, leaving separate high peaks. Earthquakes and Deformation of the Crust 25 Earthquakes and Deformation of the Crust 26 Earthquake • vibration of the Earth • produced by the rapid release of energy Earthquakes and Deformation of the Crust 27 • Elastic Rebound Theory explains the cause of earthquakes. Earthquakes and Deformation of the Crust 28 Elastic Rebound Theory Earthquakes and Deformation of the Crust 29 Elastic Rebound Theory • Rocks are moving slowly on either side of a fault • if the fault is locked in place, stress in the rocks increases • Rocks that are strained past a certain point will fracture, move, and spring back to their original shape Earthquakes and Deformation of the Crust 30 Locked • When friction prevents the rocks on either side of a fault from sliding past each other Earthquakes and Deformation of the Crust 31 • Most earthquakes occur along or near the edges of the earth’s – lithospheric plates • Fault Zone – group of interconnected faults Earthquakes and Deformation of the Crust 34 San Andreas Fault Zone • has formed where the edge of the Pacific plate is slipping north along the North American plate Earthquakes and Deformation of the Crust 35 San Andreas Fault zone Earthquakes and Deformation of the Crust 36 Aftershocks • tremor that follows a major earthquake • is smaller • Caused or related to the major earthquake Earthquakes and Deformation of the Crust 37 Focus • zone along a fault where slippage first occurs • produces an earthquake • 0rigin of the quake Earthquakes and Deformation of the Crust 38 Epicenter • point on the Earth’s directly above the focus of an earthquake • May or may not be the point of greatest shaking, most damage Earthquakes and Deformation of the Crust 39 Focus and Epicenter Earthquakes and Deformation of the Crust 40 Seismograph • instrument for recording seismic waves Earthquakes and Deformation of the Crust 42 Seismograph Earthquakes and Deformation of the Crust 43 Seismograph Earthquakes and Deformation of the Crust 44 Modern Day Seismograph Earthquakes and Deformation of the Crust 45 Richter Scale • Measure of the magnitude of a quake, or energy released • 31.7 times more energy is released for every whole number • 3.1 to 5.1? • 31.7 x 31.7 = approx. 1000 Earthquakes and Deformation of the Crust 46 Seismic Waves Earthquakes and Deformation of the Crust 48 P waves S waves L waves Speed Fastest Middle Slowest Amplitude Smallest Middle Largest Period Shortest Middle Longest Medium Solid, Solids gas, liquid On the Surface Earthquakes and Deformation of the Crust 49 Earth Quake Location Earthquakes and Deformation of the Crust 50 Earth Quake Location Earthquakes and Deformation of the Crust 51 Earth Quake Location Earthquakes and Deformation of the Crust 52