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103 Cards in this Set
- Front
- Back
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FAULT
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A FRACTURE, OR BREAK, IN THE EARTH'S LITHOSPHERE, ALONG WHICH BLOCKS OF ROCK MOVE PAST EACH OTHER
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STRESS
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THE FORCE EXERTED WHEN AN OBJECT PRESSES ON, PULLS ON, OR PUSHES AGAINST ANOTHER OBJECT.
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EARTHQUAKE
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A SHAKING OF HTE GROUND CAUSED BY THE SUDDEN MOVEMENT OF LARGE BLOCKS OF ROCK ALONG A FAULT.
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WHAT CAUSES AN EARTHQUAKE
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A SUDDEN RELEASE OF STRESS IN THE LITHOSPHERE.
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LITHOSPHERE
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THE EARTH'S CRUST AND THE VERY TOP OF THE MANTLE. THIS IS THE MOST RIGID OF ALL LAYERS.
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WHERE DO MOST EARTHQUAKES OCCUR?
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ALONG TECTONIC BOUNDARIES WHICH IS WHERE MOST FAULTS ARE LOCATED.
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WHAT DOES THE STRENGTH OF AN EARTHQUAKE DEPOND ON?
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1. HOW MUCH STRESS BUILDS UP BEFORE THE ROCKS MOVE; AND
2. THE DISTANCE THE ROCKS MOVE ALONG THE FAULT. |
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WHAT PERCENTAGE OF EARTHQUAKES OCCUR AROUND THE PACIFIC OCEAN?
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80%
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ABOUT 80% OF ALL EARTHQUAKES OCCUR WHERE?
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IN A BELT AROUND THE EDGES OF THE PACIFIC OCEAN.
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WHAT IS THE NAME OF HTE BEST KNOWN FAULT IN THE US?
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SAN ANDREAS FAULT IN CALIFORNIA.
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WHERE IS THE SAN ANDREAS FAULT LOCATED?
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CALIFORNIA
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WHAT IS THE NAME OF THE FAULT THAT FORMS THE BOUNDARY BETWEEN THE NORTH AMERICAN PLATE AND THE PACIFIC PLATE?
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SAN ANDREAS FAULT
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THE SAN ANDREAS FAULT FORMS THE BOUNDARY BETWEEN THE ___ ____ ___ AND THE ____ ___.
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NORTH AMERICAN PLATE; PACIFIC PLATE
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THE SAN ANDREAS FAULT CAN BE SEEN ON THE SURFACE OF THE GROUND
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TRUE
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A SMALL PERCENTAGE OF EARTHQUAKES OCCUR ALONG FAULOTS WITHIN PLATES. T OR F
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TRUE
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A TECTONIC PLATE IS RIGID. THEREFORE, STRESS ALONG A PLATES BOUNDARY CAN CAUSE ROCKS TO BREAK AND MOVE ALONG WEAK AREAS TOWARD THE MIDDLE OF THE PLATE. T OR F
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TRUE
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Where do all earthquakes occur?
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In the Lithosphere
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Why do all earthquakes occur in the lithosphere?
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Because the tectonic plate is rigid & brittel, rocks break, move suddenly causing an earthquake
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Why do earthquakes NOT occur in the asthenosphere?
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In the astenosphere, rocks are hot so they bend & flow rahter than break.
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Why do a fe earthquakes occur below the lithosphere?
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Because the tectonic plates sinking in subduction zones are still cold enough to break
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Subduction
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When one plate sinks beneath another
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Tectonic Plates
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When lighosphere is broken into many large & small slabs of rock.
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How are faults classified?
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By how rocks move.
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What causes blocks of rocks to move in different directions?
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Types of stress
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How do scientists classify a fault?
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By the way the rocks on one side move w/respect to the rocks on the other side.
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How many types of faulths are there?
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3
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Name the 3 types of faults.
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Normal, Reverse, Strike-Slip.
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Can more than 1 type of fault be present along the same plate boundary?
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Yes
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The type of fault that is most comon along a boundary depends on whether plares are:
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1. Pulling apart;
2. Pushing toether; or 3. Scraping past one another. |
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How do blocks move along a normal or reverse fault?
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Verticle or up and down.
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How do blocks move along a strike-slip fault?
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Horizontal or move sideways
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Normal Faults are caused by what type of stress?
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Stress that pulls rocks apart.
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Where ar enormal faults common?
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Great Rift Valley of Africa
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Why are normal faults common in the Great RIft Valley of Africa?
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Because tectonic plates are moving apart.
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What type of stress causes reverse faults?
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Stress that presses rocks together.
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Know what the arrows mean/indicate in the photos on pg. 224
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see pg. 224
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Where can Reverse Faults occur?
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Near collisoin-zone boundaries between plates.
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Name a location htat has Reverse Faults
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Himalaya Mountains
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How do blocks of rock move in a Strike-slip fault?
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They move sideways on either side of the fault plane.
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What type of stress causes Stike-Slip Faults?
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Stress that push blocks of rock horizontally
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Where do Strike-slip faults occur?
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Where plates scrape past each other.
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Name a locaito where Strike-Slip Faults occur.
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The San Andreas Fault.
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Over time, movement of rocks along normal & revers faults can push up _________ and form deep __________.
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Mountains; valleys.
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When looking at an illustration of a fault, show the direction of the arrows for a Normal Fault, Reverse Fault, & Strike-Slip fault.
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show examples
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How does earthquakes energy travel?
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Outward in all directions - up, down, & to the sides.
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Seismic Waves
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Vibrations caused by earthquakes.
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Where do all earthquakes start?
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Beneath earth's surfact.
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Focus
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The point underground where rocks first begin to move in an earthquake.
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Seismic waves travel _____ from the earthquakes focus.
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Outward.
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Epicenter
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The point on Earth's surface directly above the focus.
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How do scientists name an earthquake?
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After the city that is closest to its epicenter.
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If 2 earthquakes of equal strength have the same epicenter, which one will cause more damage?
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The one w/the shallower focus.
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What is the difference between the focus & the epicenter of an earthquake?
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The focus in below ground, the epicenter is above ground.
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Earthquakes produce how many tuypes of seismic waves?
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3
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Name the 3 types of seismic waves produced by earthquakes.
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1. Primary
2. Secondary 3. Surface |
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Scientists learn about Earth's layers by studying the _____ & _____ of seismic waves traveling through Earth.
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Paths; speeds
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P Waves =
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Primary Waves
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What are the fastest seismic waves?
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Primary
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Which wave reaches a location first after earthquakes?
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Primary
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What materials can Primary Waves trave through?
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Solids, liquids, gases.
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Primary Waves move in what direction?
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Push & Pull
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S Waves =
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Secondary Waves
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Which waves reach a locaiton second in an earthquake?
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Secondary
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What material can Secondary waves travel through?
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Rock
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When a secondary wave passes, the material changes slightly in _____.
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Shape
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Secondary waves move how?
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up-down; side-side
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Why can't secondary waves travel through liquids or gases?
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Because secondary waves change a materials shape. Liquids & gases don't hae a shape.
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can secondary waves pass through Earth's outer core?
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No.
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Surface Waves
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Seismic waves that move along Earth's surface, not its inerior
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Surface waves does what to the ground?
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Roll up & down or shake side to side.
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Which waves cause the largest ground movements & the most damage?
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Surface
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Which waves travels the slowest?
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Surface
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Be able to identify types of waves by illistration
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pg. 231
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When or where are earthquakes most dangerous?
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When they ocur near areas where many people live
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Who developed the first earthquake scale?
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Charles Richter Beno Gutenberg
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What it the name of the scale?
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The Richter scale
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What does the Richter scale measure?
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An earthquakes magnitude which is based on how fast the ground moves at a seismic station.
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What is the moment magnitude scale?
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A scale that measures the total amouts of energy released by earthquakes
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Which scale today do most scientist prefer to use?
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Moment Magnitude Scale
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The Richter & Moment Magnitude Scale are often shown w/a top value of 10. Is this the maximum value?
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No. Neither scale actually has amaximum value
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On both scales, an increas of 1 whoe number indicates an increase of ____ times more energy.
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32 times
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Which scale is more accurate for large eqrthquakes?
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Moment Magnitude Scale
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What is an advantage of using the Moment Magnitude Scale?
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1. More accurate for large earthquakes.
2. Can be used for earthquakes that occurred before seismographs were invented. |
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How can scientists calculate a past earthquakes magnitude?
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By measuring the strength of the rocks & the length they moved alon a fault.
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Aftershock
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A smaller earthquake that follows a more powerful earthquake in the same area.
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Liquefaction
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A process in which shaking of the ground causes soil to act like a liquid.
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Liquefaction only occurs in what type of areas?
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Areas where the soil is made up of loose sand & silt & contains a large amount of water.
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List 5 ways in which earthquakes can cause damage.
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1. Collapse of structures;
2. Fires; 3. Landslides; 4. liquefaction; and 5. Crack roads, buildings, and dams |
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Tsunami
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A water wave triggered by an earthquake, volcanic eruption, or landslide.
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Can tsunami waves have different heights?
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yes
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Can tsunami waves arrive hours appart?
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yes
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What speed can tsunamis reach in deep water?
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700 kilo/her (430 mi/h)
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Many earthquakes occur around the edges of the ______ ocean.
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Pacific
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Where is the tsunami warning center located?
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Hawaii
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Can scientists predict where an earthquake will occur?
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No
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What do scientists study to help predict earthquakes?
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Seismic activity along faults
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What are 3 signs of stress building up in rocks along faults?
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1. tilts or changes in the elevation of the ground;
2. Slow movement or stretching in rock; 3. Development of small cracks in ground. |
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Seismic Gap
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An area of few or no earthuakes that is surrounded by many earthquakes.
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A seismic gap can indicate a location where a fault is _______.
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Stuck
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Why can a lcak of earthquakes in an area near an active fault cause concern?
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Because movement along other parts of the fault can increase stress along the "stuck" part & the stress could cause a major earthquake.
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Structures can be designed to resist earthuake damage
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?
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Name 3 methods that help make structures safer from earthquakes.
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1. by installing base isolators;
2. Open space or moat; 3. shear walls |
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Base Isolator
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made of flexible material, stacked in layers, placed between a building and its foundation.
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