Earthquakes Introduction What is an Earthquake An earthquake

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Earthquakes – Introduction

Earthquakes – Introduction

What is an Earthquake? • An earthquake is the vibration of Earth produced by

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

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

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 /

Fault Terminology • • Hypocenter Faults Epicenter Elastic Rebound Foreshocks Mainshock Aftershock 5 / 88

Types of Faults 6 / 88

Types of Faults 6 / 88

Dip Slip Faults Hanging wall Footwall Movement is primarily vertical and parallel to the

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

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

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

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: Reverse faults Source: 4 11 / 88

Dip Slip Faults: Thrust faults Source: 5 12 / 88

Dip Slip Faults: Thrust faults Source: 5 12 / 88

Strike Slip faults • Dominant displacement is horizontal and parallel to the strike of

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

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.

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