EARTHQUAKES IN ALABAMA

Mrs. Alison StarrAuburn High School

Auburn, AL

Concepts to Address

1. Describe the formation of earthquakes based on plate boundary movement.

2. Explain the Richter-Scale and the standards by which we assess earthquakes.

3. Describe the fault zones that impact Alabama.

Assessments

Must turn in the following in your Earthquake Journal. Journal entry #1- Question 1-18 on VFT Journal entry # 2- Describe the events that

you might have experienced2 in Fort Payne, Alabama on April 29, 2003.

Journal entry #3 -Maps of United States and Alabama

Journal entry #4- Pamphlet on Earthquake Readiness in Alabama

Introduction

Earthquakes are the most unpredictable, powerful forces that impact Earth.

Earthquakes occur across the globe , along fault lines.

About 75 earthquakes occur each year with a few being of significant strength.

They can occur in small, remote villages to large cities, from California to Alabama.

Haiti Earthquake http://www.youtube.com/watch?v=79S-6UqGCbU&safety_mode=true&persist_safety_mode=1

Questions

Question#1: What type of stresses impact the Earth’s rock layers?

Question # 2: Why does the Earth shake?

Question # 3: Draw and label the movement of the plates at a reverse fault,

normal fault, and a strike/slip fault.

Three types of stresses that can affect Earth’s rock layers

1.Compression- decreases the volume of a material.

2. Tension-pulls a material apart3. Shear- causes a material to twist

Typical Stress-Strain Curve Elastic Deformation- the rubber band is being

stretched more and more Elastic Limit- the rubber band begins to tear and

get small holes Ductile deformation- the rubber band continues to

get holes and tear more Failure- the rubber band breaks.

Faults

Types of Fault Reverse Fault Normal Fault Strike-Slip Fault

Cause Horizontal compression

Horizontal tension

Horizontal shear

Movement Horizontal shortening of crust involved

Partly horizontal and partly vertical

Mainly horizontal

Faults are formed along fractures where movement has occurred due to the stress but upon the rocks. Fault movement takes place on a fault plane, which can be vertical, horizontal, or at an angle. There are three types of faults.

Why does the earth shake?

The Elastic Rebound Theory, H.F. Reid, states; “The deformed rocks, store energy and bend, when they rupture energy is released in the form of earthquake waves that radiate outward in all directions.

http://earthquake.usgs.gov/learn/animations/animation.php?flash_title=Elastic+Rebound&flash_file=elasticrebound&flash_width=300&flash_height=350

Small tremors or earthquakes called foreshock precede a major earthquake.

After a major earthquake aftershocks follow for hours days even weeks after a major event And aftershock is usually weaker.

Question

Question #4: What is the difference between the epicenter and focal

point?

Question #6: What is the relationship between plate boundaries and focal

depth.?

Question #7: Name the four types of seismic zones. Describe the

boundary at which they form and give a brief explanation and include an example of each.

Where does it all begin?

The place where the rupture starts is referred to as the focus.

The epicenter, not focus, is usually given in news reports to identify location of rupture.

Three Types of Focus and Fault types

Shallow-focus most destructive most in California are this type.- Focial depth at least 70 km- Form on divergent or transform plates

Intermediate- focus- Focial depth 70 km-300km- Occur within circum- pacific belt- Convergent boundaries

Deep- Focus- Focial depth more than 300 km- Occurs within circum-pacific belt - Convergent boundaries

Seismic Zones

http://earthquake.usgs.gov/learn/topics/plate_tectonics/rift_man.php

Plate Tectonics

Question

Question #8: What is the difference between a P-wave and an S-wave? Question #9: How do scientist determine the epicenter of an earthquake?

Question #10: What role did Cheng Heng play in the development of the

seismograph.

Question #11: What do seismologist do?

Question # 12: Name and describe the two seismic belts where earthquakes

are active.

Seismology

The science of earthquakes is seismology.

- Seismologist use a seismograph to measure earthquake waves.

A Chinese scholar , Chang Heng, Was the first to invent an earthquake detector in 132 A.D

Today we use a seismograph that pick up all three type of seismic waves, surface waves, p-wave, and S-wave. The difference, between P- waves and S-

waves help locate epicenter.

Surface Wave

Travel along Earth’s surface, move in two directions as they pass through the rock.

Visual aid: http://earthquake.usgs.gov/learn/glossary/?ter

m=surface%20wave

P- vs. S- Wave

P-waves squeeze and pull rocks in the same direction as the wave

S-waves cause rocks to move at right angles to the wave

Both waves move the Earth’s interior P- and S- wave simulation

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1002/es1002page01.cfm

Distance and Direction

Earthquake distance is determined by the use of a seismogram and physical evidence

Earthquake direction uses travel-time graphs from 3+ seismograms to final exact location of epicenter.

Distribution of Earthquakes

95% of all earthquakes occur along seismic belts that correlate to the plate boundaries- 80% occur along the circum Pacific belt

- convergence zone - Most devastating earthquake

- 15% - Mediterranean Asiatic belt- 5%- occur in interior plates and along ocean

ridges.- Charleston, SC- Missouri Earthquake

Earthquake Zones

Retrieve your map of the United States. Label each state with earthquake activity Color the zones of seismic activity.

Journal

Question # 13: Describe the Modified Mercalli scale.

Question # 14: Explain the Richter Scale.

How do we Measure?

Intensity and Magnitude of an Earthquake The most common intensity scale is the

Modified Mercalli Intensity Scale , used in the US. 1956 2010

The measure of magnitude is the Richter-Scale. To avoid large numbers Richter used a base-10

logarithmic scale to convert the amplitude of the largest seismic wave to a numerical magnitude value.

Question

Question #15: How can an earthquake change the characteristics of a place

and what processes take place?

Effects of Earthquakes

Ground shaking Solid rock foundations suffer less damage. Consolidated or water saturated foundations can undergo

liquefaction. Surface can split open along fault. http://video.nationalgeographic.com/video/player/environment/env

ironment-natural-disasters/earthquakes/earthquake-montage.html

Fire Ruptured gas and water lines 90% of all damage caused by fire in the 1906 San Francisco quake. Infrastructure damage

Tsunami Travel at speeds of several hundred km/hr

Landslides Avalanches

Alabama Earthquake Information

Question #16:What are the zones that impact Alabama and describe the

location of each zone. Question #17:What does CUSEC stand for and explain its purpose? Journal entry:Describe the events that you might have

experienced in Fort Payne, Alabama on April 29, 2003. Include descriptions of earthquake tremors, intensity

of tremors, your feelings during and after the earthquake, and any visual observations of surrounding environmental changes.

Earthquakes in Alabama, really?

Largest Earthquake in State History History of quakes in Alabama Most recent activity

Fault types Alabama is impacted by three zones.

Coaliation Alabama joins the CUSEC on September 26,

2003

Map of Alabama

Retrieve map of State of Alabama. Go to Sesmic Activity Map.

Place the epicenter of each earthquake on your map along with the Richter-Scale reading, date, and location.

How do we respond?

Question # 18: How does the international community respond to divesting

earthquakes?

http://www.fema.gov/hazard/earthquake/index.shtm Go the the FEMA site to answer Question 18

and help create your pamphlet on Earthquake readiness.