Earthquakes Introduction What is an Earthquake An earthquake
- Slides: 18
Earthquakes – Introduction
What is an Earthquake? • An earthquake is the vibration of Earth produced by the rapid release of energy 2 / 88
Where are earthquakes located? Subduction Zones Boundaries Spreading Centers Continent-Continent Intraplate 3 / 88
What is a Fault? • Faults are fractures in the crust along which appreciable displacement has occurred. Source: 1 4 / 88
Fault Terminology • • Hypocenter Faults Epicenter Elastic Rebound Foreshocks Mainshock Aftershock 5 / 88
Types of Faults 6 / 88
Dip Slip Faults Hanging wall Footwall Movement is primarily vertical and parallel to the fault plane May produce long, low cliffs called fault scarps
Dip Slip Faults: Normal • Hanging wall block moves down relative to the footwall block • Accommodate lengthening or extension of the crust • Fault-block mountains Source: 3 8 / 88
Dip Slip Faults: Normal Large normal fault in Triassic to Lower Jurassic Blue Anchor Formation sediments near Blue Anchor, Somerset, UK. Source: 2 9 / 88
Dip Slip Faults: Reverse faults • Hanging wall block moves up relative to the footwall block • Reverse faults have dips greater than 45° • Thrust faults have dips less then 45° • Accommodates shortening of the crust (compression) Source: 3 10 / 88
Dip Slip Faults: Reverse faults Source: 4 11 / 88
Dip Slip Faults: Thrust faults Source: 5 12 / 88
Strike Slip faults • Dominant displacement is horizontal and parallel to the strike of the fault • Right-lateral • Left-lateral • Transform fault Source: 3 13 / 88
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Preparing for Earthquakes • We can’t stop them but we can be ready for them. – – Train the community in earthquake preparedness. Run preparedness drills. Educate individuals on safe behavior and responses. Keep viable stores of emergency supplies. 16 / 88
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1. 2. 3. 4. 5. http: //en. wikipedia. org/wiki/San_Andreas_Fault#mediaviewer/File: Kluftphoto-Carrizo-Plain-Nov-2007 -Img_0327. jpg http: //en. wikipedia. org/wiki/Fault_%28 geology%29 http: //www. iris. edu/hq/programs/education_and_outreach/animations/2 http: //clasticdetritus. com/2008/09/19/friday-field-foto-64 -nice-z-fold-inpatagonian-outcrop/ http: //upload. wikimedia. org/wikipedia/commons/a/a 2/Thrust_fault_Qilian_S han. jpg 18 / 88
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