Earthquakes Marc Daniels Earth Science. Lesson 1: Where Do Earthquakes Occur and Types of Earthquakes/Faults This will go over where earthquakes potentially.

EarthquakesEarthquakes

Marc DanielsMarc Daniels

Earth ScienceEarth Science

Lesson 1Lesson 1: : Where Do Earthquakes Occur Where Do Earthquakes Occur and Types of Earthquakes/Faultsand Types of Earthquakes/Faults

• This will go over where earthquakes potentially can occur, as well as the different type of earthquakes that include normal, reverse, and strike-slip faults. This will include the motions due to each fault as well as elastic rebound theory.

• To study Earthquakes we first must know where they possibly can occur.

• We typically find earthquakes near Faults

• Faults are fractures in rock along which movement has occur. There are three different kinds of faults that are: Normal, Reverse, and Strike-Slip faults

Normal FaultsNormal Faults

• Normal Faults (also known as dip-slip)- obey the laws of gravity

• They are caused by dilation (pulling apart)• In this case, the “hanging wall” drops down

Reverse FaultsReverse Faults

• Reverse Faults (dip-slip or thrust faults)• They are caused by compression• In this case, they “footwall” drops down

Strike-Slip FaultsStrike-Slip Faults

• Strike-Slip Faults• Strike-Slip Faults are caused by Sheer• Nothing drops in this case, and land along

the fault moves in opposite directions

• There are two different types of strike slip faults

Right-Lateral Strike Slip FaultsRight-Lateral Strike Slip Faults

• Right lateral- in relation to observation point the land has moved to the right

Left-Lateral Strike Slip FaultsLeft-Lateral Strike Slip Faults

• Left Lateral- in relation to observation point the land has moved to the left

What Kind Of Fault Is This???What Kind Of Fault Is This???

What Kind Of Fault Is This???What Kind Of Fault Is This???

What Kind Of Fault Is This???What Kind Of Fault Is This???

ElasticElastic ReboundRebound TheoryTheory

• E.R.T is a result of the movement that causes deformation

• Ruptures and Release of Energy (stored energy is released at the point of rupture)

• Rocks “Rebound” to original unreformed shape

EarthquakesEarthquakes

• All the movement along the faults are driven by the movement of plates

• Most Earthquakes are

found along plate

boundaries

Lesson 2 and 3:Types of Seismic Waves, Lesson 2 and 3:Types of Seismic Waves, Ways to Measure Intensity, and The Ways to Measure Intensity, and The

Kinds of Waves that Different Types of Kinds of Waves that Different Types of Earthquakes/Faults createEarthquakes/Faults create

• Lesson 2: This section of the unit discusses the different kinds of waves an earthquake generates, and how those waves are measured and what they mean. This also includes ways that we measure an earthquake’s intensity.

• Lesson 3: This is more of a follow up to the previous section, but this will focus on how we can tell what type of earthquake has occurred based on seismographs, this possibly will include how we locate where an earthquake has occurred.

Seismic WavesSeismic Waves

• Seismic Waves are created by the rupture of fault lines

• There are two sorts of waves, each with two varieties

Body WavesBody Waves

• These move through the body of the earth

• There are P (primary) and S (secondary) waves

Primary WavesPrimary Waves

• P waves (Primary Waves)

The fastest wave

Can move through any material

Are compression waves

(Example: Slinky)

Secondary WavesSecondary Waves

• S waves (Secondary Waves) • Slower than P waves• Can move through rigid

material (only solid)• These are sheer waves

P and S Wave MotionP and S Wave Motion

Surface WavesSurface Waves

• Surface Waves

• These move on the surface of the earth

• They include Rayleigh and Love Waves

Rayleigh Waves and Love Waves (may or Rayleigh Waves and Love Waves (may or may not be discussed)may not be discussed)

• Rayleigh Waves

Are Slower

Have a vertical motion• Love Waves

Have a horizontal motion

How are Seismic Waves measured?How are Seismic Waves measured?• Seismic Waves are recorded by a Seismograph which produces a

Seismogram

• (Side Note: as the wave gets further away from the focus. The P-wave pulls ahead of the S-wave)

Using the P-S time interval we can determine the distance from the earthquake

• This becomes a method for measuring distances from the station to the epicenter.

The Difference between the Focus and The Difference between the Focus and EpicenterEpicenter

• Focus- The place within the Earth where an earthquake originates and energy is released

• Epicenter- The point on Earth’s surface vertically above the focus.

What kind of fault is this??

Motion Studies (may or may not be Motion Studies (may or may not be discussed, compression and dilation)discussed, compression and dilation)

• The first P wave tells us if there is compression or dilation, and by using seismographs we can tell which direction faults are moving

• If there is Compression, the earth moves down (seismogram shows an upward movement)

• If there is Dilation, the earth moves up (seismograph shows a downward movement)

The Movement of Faults and Their The Movement of Faults and Their Seismic WavesSeismic Waves

• Normal Fault- compression p waves in all directions/ dilation at the fault

The Force is Dilationat the Fault

The P wave expressed is Compression

The Movement of Faults and Their The Movement of Faults and Their Seismic WavesSeismic Waves

• Reverse Fault- dilation p waves in all directions/ compression at the fault

The Force is Compressionat the Fault

The P wave expressed is Dilation

The Movement of Faults and Their The Movement of Faults and Their Seismic WavesSeismic Waves

• Strike-Slip Fault- both dilation and compression p waves

• There are both forces of Dilation and Compression, but they differ depending on if the fault is left or right lateral

The Movement of Faults and Their The Movement of Faults and Their Seismic WavesSeismic Waves

• Left Lateral

The Movement of Faults and Their The Movement of Faults and Their Seismic WavesSeismic Waves

• Right Lateral

How To Measure The Intensity of How To Measure The Intensity of EarthquakesEarthquakes

• One way is by using the Richter Magnitude Scale

• This measures the amount of energy released (uses distance and the amplitude of a wave to get the magnitude)

Richter Magnitude ScaleRichter Magnitude Scale

How To Measure The Intensity of How To Measure The Intensity of EarthquakesEarthquakes

• Another way is using the Modified Mercalli Intensity Scale

• This is based on the amount of damage done by earthquakes and what people experience during them

The Mercalli Intensity ScaleThe Mercalli Intensity Scale

Lesson 4: Historical Earthquakes and Lesson 4: Historical Earthquakes and Possible Hazards and Damages Caused Possible Hazards and Damages Caused

by Earthquakesby Earthquakes

• This section of the unit will be more group work/ project focused. The goal would be to discuss possible hazards created by earthquakes, and the possible damages that can be caused here.

• Students will be given the opportunity to point out particular risks given aspects of information such as fault location and possible hazards in the area, and students will be given the opportunity to create their own evacuation plan for an area of their choosing (possibly fictional). Their plans will be presented during class.

Historical EarthquakesHistorical Earthquakes

• Earthquake off the west coast of North Sumatra

• December, 2004• Magnitude of 9.1• 283,106 fatalities

– From earthquake– And Tsunami

• Fourth largest earthquake

since 1900

http://upload.wikimedia.org/wikipedia/commons/4/47/2004_Indonesia_Tsunami_Complete.gif

Historical EarthquakesHistorical Earthquakes• Earthquake in India• January 2001• Magnitude of 7.7• 20,023 fatalites• 600,000 people were left homeless, 1• Almost half the population of 37.8 million

afffected. • Thousands of Cattle lost• Losses recorded from $1.3 billion to $5

billion.

Historical EarthquakesHistorical Earthquakes

• Earthquake in Turkey

• August of 1999

• 7.6 magnitude

• 17,118 fatalities

• Continuous Aftershocks

• Devastating Damages

Historical EarthquakesHistorical Earthquakes

• Earthquake near Fiji Islands

• 1997

• Magnitude of 7.8

• Occurred in the water

• No Fatalities

Causes of Earthquake DamageCauses of Earthquake Damage

• 1) Ground Shaking- (As a result of S-waves and Surface Waves)

• 2) Liquefaction– Loose, water-saturated sand– Deformation jostles the grains– Water in between the grains, surrounds the grains

so there is no friction– Material is able to flow like a fluid

Liquefaction Demonstration!!!

Causes of Earthquake DamageCauses of Earthquake Damage

• 3) Fault Movement

• 4) Landslides

• 5) Fires

Causes of Earthquake DamageCauses of Earthquake Damage

• 6) Tsunamis- Great Waves

Ways to Assess Earthquake HazardsWays to Assess Earthquake Hazards

• 1) Observing Faults and the probability of movement (likely to observe near costal regions and mountainous regions)

• 2) Underlying Material (what are structures and buildings built on)

(soft materials amplify seismic waves but is slowed down)

Earthquake ClipsEarthquake Clips

• Taiwan and California Earthquakehttp://www.youtube.com/watch?v=4Y62Ti5_6s&feature=related

• Los Angeles, California Earthquakehttp://www.youtube.com/watch?v=mcoHJHo8d6k&feature=related

• California Earthquakehttp://www.youtube.com/watch?v=0lAXStQCjr8&feature=related

• Peru Earthquakehttp://www.youtube.com/watch?v=uPsAcVLWtps&feature=related

• Kona, Hawaii Earthquakehttp://www.youtube.com/watch?v=o7yThRfO9_4&feature=related

In Class DiscussionIn Class Discussion

• What hazards are seen in these clips?

• What are other possible hazards or dangers in these areas?

What is Resonance?What is Resonance?

• resonance is the tendency of a system to oscillate at maximum amplitude at certain frequencies, known as the system's resonance frequencies (or resonant frequencies). At these frequencies, even small periodic driving forces can produce large amplitude vibrations, because the system stores vibrational energy. When damping is small, the resonance frequency is approximately equal to the natural frequency of the system, which is the frequency of free vibrations. Resonant phenomena occur with all type of vibrations or waves; mechanical (acoustic), electromagnetic, and quantum wave functions. Resonant systems can be used to generate vibrations of a specific frequency, or pick out specific frequencies from a complex vibration containing many frequencies.

Resonance and EarthquakesResonance and Earthquakes

Machines – Many of the physical limitations of machines,

including vehicles and manufacturing plants, are determined by their susceptibility and resistance to vibrations.

– The most destructive vibrations are often those at resonant frequencies of some part of the machine.

Information from: http://oolong.co.uk/resonata.htm

Resonance and EarthquakesResonance and Earthquakes

• Buildings – The buildings which are most damaged by

earthquakes are often those unfortunate enough to have a resonant frequency matching the frequency of the quake.

– Tall buildings are built with structures and dampers to resist the damage due to resonance.

Information from: http://oolong.co.uk/resonata.htm

Resonance and BridgesResonance and Bridges

• Bridges – Armies are trained to break step when crossing

bridges; if they all marched in time, and their pace happened to match a resonant frequency of the bridge, there would be a serious danger of collapse.

– The Tacoma Narrows Bridge was ripped apart by a complicated resonance effect, with the 40mph wind forming periodic vortices which mutually reinforced the turning motion of the bridge.

Information from: http://oolong.co.uk/resonata.htm

Tacoma Narrows Bridge VideoTacoma Narrows Bridge Video

• http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge

• http://www.youtube.com/watch?v=3mclp9QmCGs

Types of Surfaces and Types of Surfaces and EarthquakesEarthquakes

In-class activity: Building Your In-class activity: Building Your Own BridgeOwn Bridge

• http://www.newbaybridge.org/classroom/engineeringfor.html

• What geographical features can pose possible hazards? (when building bridges, buildings etc?)

• Browse the website to learn about possible bridge structures that can survive an earthquake

• What factors (devices) help prevent a bridge from collapsing in an earthquake?

Group Mini ProjectGroup Mini Project

• Taking two of the clips, design a possible evacuation plan for the people living in the area.

• Include the hazards that are present, and ways to possibly avoid or prevent those hazards

Recap: Ways to Assess Earthquake Recap: Ways to Assess Earthquake HazardsHazards

• 1) Observing Faults and the probability of movement (likely to observe near costal regions and mountainous regions)

• 2) Underlying Material (what are structures and buildings built on)

(soft materials amplify seismic waves but is slowed down)

Earthquake ClipsEarthquake Clips

• Taiwan and California Earthquakehttp://www.youtube.com/watch?v=4Y62Ti5_6s&feature=related

• Los Angeles, California Earthquakehttp://www.youtube.com/watch?v=mcoHJHo8d6k&feature=related

• California Earthquakehttp://www.youtube.com/watch?v=0lAXStQCjr8&feature=related

• Peru Earthquakehttp://www.youtube.com/watch?v=uPsAcVLWtps&feature=related

• Kona, Hawaii Earthquakehttp://www.youtube.com/watch?v=o7yThRfO9_4&feature=related