Geology 103 Exam 2 USC – Flashcards

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Natural Disaster
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Natural Process that causes great loss of life OR property OR BOTH. 10+ ppl are killed. 100+ ppl are affected. State of emergency is declared. Earthquakes, flooding, hurricanes.
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Magnitude- Frequency Concept
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Natural disasters are measured by their impact
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Magnitude
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amount of energy released. The higher the magnitude, the less frequent.
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Frequency
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recurrence interval. The lower the magnitude, the more frequent.
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Natural Catastrophe
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Natural hazard that damages so severely that recovery/ rehab is extensive and lengthy. flood, hurricane, earthquake, volcano, tornado/wind storm, wildfire
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disasters now being considered catastrophes
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more people on earth and more land being used
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Weather emergency preparedness quiz.. What is the difference between a "Warning" and a "Watch"?
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A: "Warning" means that an event has been sighted; seek shelter.
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Prediction
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specifies date, time, size of event
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Forecast
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includes ranges of certainty
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5 elements to reducing risk
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1. location 2. Probability 3. Precursor events 4. Prediction 5. Warning
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Hurricane Season
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June-November
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Which of the following conditions below would NOT indicate a natural disaster?
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Request for international assistance
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Nevado del Ruiz Volcano in Colombia
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Lahars strke suddenly, can spread out across large areas and lay down a thick layer of mud that buries everything in its path. Buried the town of Armero and killed more than 20,00 ppl.
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Which of the following statements is true with regard to the Nevado del Ruiz volcano?
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Citizens of Armero largely ignored warnings.
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Yungay, Peru: Debris Avalanche
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1970 earthquake induced a massive debris avalanche from steep slopes of Mt. Huscaran.Traveled 1o miles at speeds of 170mph. killed 18,000 ppl. wrecked town
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Mass Wasting
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Decribes downslope movements of rock and/or soil
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Landslide
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A general term in widespread use to describe all varities of mass movements (slumps, slides, flows, avalanches, etc.) Rock and debris slide.
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Shape of slopes
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Strong rocks form a cliff (free face) and talus slope. No soil. Softer rocks form a curved slope (with convex, straight, and concave segments) and are typically covered by soil. (more common)
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talus (scree)
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pile of rocks at the bottom of cliff. Produced by rock falls
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Rotational Landslides
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SLUMPS: movement along a curved failure surface as a series of coherent blocks or plugs of material. smaller than slides. Scar at top of slump showing where material used to be. moves as a coherent mass, not a chaotic flow.
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Translational Landslides
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SLIDES: movement along a planar surface (often a bedding plane or fault). Larger and faster than slumps. Trees stay upright. Telephone pole example
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In a typical slump, the glide surface (slip surface) is _______ , and at the uphill end, a(n) ________ forms.
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curving (spoon-shaped) / head scarp
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Falls
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Movement is vertical. occur on highly steepened and rocky slopes, commonly as a product of freeze-thaw activity.
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Rock falls
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common road side hazard in areas where the terrain is steep
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A talus slope is a feature associated with _____ and is typically associated with _____ rocks.
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rock falls / strong
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Flows
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downslope mvmt of unconsolidated material. moves down slope as viscous fluid.
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Soil Creep
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very slow. freeze/thaw. creates tilted things.
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earth flow
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faster, usually partially liquefied, hourglass shape
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Debris/mud Flow
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mixture of rock, soil, water moving quickly. If the material is mostly mud, the flow is a mud flow. If it is a mixture of mud with abundant boulders and trees it is a debris flow.
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Avalanche
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turbulent cloud of debris mixed with air.
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Complex Slide
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Combination of slides, slumps and flows in one event
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Geologists distinguish among different kinds of downslope movement based, in part, on ________ .
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rate of movement (speed)
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Surface tension
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forces exerted by the film of water that covers the grains in slightly wet sand make the sand cohesive when compared to dry sand.
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Which of the following will INCREASE the potential for mass movement on a slope?
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deforestation
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Human Influences- timber harvesting
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removes vegetation, and can lead to mass wasting on weak, unstable slopes
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Urbanization
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areas of high densities of roads and buildings have higher mass wasting potential
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Minimizing Hazards- controlling drainage
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diverting water around the slope
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Minimizing Hazards- grading the slope
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benching or terracing a slope can increase stability
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Minimizing Hazards- slope supports
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retaining walls can support the base of a slope
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Chiesa de Santa Maria Paganica in L'Aquila, Italy
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On April 6, 2009 a 6.3 magnitude earthquake struck. The epicenter was near the town of L'Aquila. Not built for earthquake resistant standards. can't predict earthquakes, early warning system may not work for moderate quakes.
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Force
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=mass X acceleration.
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Stress
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=force/area. The stress exerted by the heel is greater than the stress exerted by the toe because the area of the heel part of the shoe is much smaller than the area of the toe part of the shoe. Little stress is required to produce strain in a marshmallow. Much more stress is required to produce strain in a big steel pipe.
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Strain
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change in shape that an object experiences in response to an applied stress. (Deck of cards)
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Compression
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--> <---
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Shearing
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-----> <----
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Above, we see a cross section of a cube that undergoes ______ in the horizontal direction.
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compression
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Earthquakes occur when...
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rock that is under stress suddenly breaks along fault plane sending ground vibrations or seismic waves, in all directions through the Earth and along the Earth's surface.
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Body Waves
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Move through the interior of the Earth. refracted when they encounter denser layers of rock at depth
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P-waves
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(Primary Waves - Compressional Wave) fastest moving. vibrates back-and-forth in the direction that the wave is moving. smack top of water and reaches bottom. do not arrive in the P-wave shadow zone because they refract at the core-mantle boundary.
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S- Waves
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(Secondary Waves- Shear Waves) the rocks vibrate up-and-down at 90° to the direction of wave propagation. slower than P waves. cannot move through liquids-> how geologists know earths outer core is partially molten rather than solid rock. swish ur hand through water at surface- not transmitted to the bottom of the pool.
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Elliptical waves
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move with circular rotation
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Transverse waves
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shake back & forth across ground surface
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Surface Waves
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Surface waves are by far the greatest source of ground shaking and destruction that occurs at the Earth's surface from earthquakes.
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Which is the correct sequence of seismic waves that will be recorded at a distance from the epicenter? ? first to arrive last to arrive ?
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P-waves / S-waves / surface waves
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elastic rebound theory
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involves the build up of elastic strain and the sudden release of that strain during an earthquake
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Stick-slip behavior
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The pulling of the spring results in the build-up of elastic strain (in the spring) which is eventually released when the weight suddenly slides along the rough surface. Once the weight stops, the build-up of elastic strain begins again, and the cycle repeats itself. same behavior that is observed when a weight attached to a spring is dragged along a rough surface
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focus or hypocenter
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The energy released in an earthquake originates from a point on the fault plane
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epicenter
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The point on the Earth's surface immediately above the hypocenter
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seismograph
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instrument used to measure seismic waves created by earthquakes.
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quake magnitude
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estimates the amount of energy released at the source of the earthquake
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quake Intensity
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a measure of the degree of earthquake shaking at a given locale based on the amount of damage. The intensity of ground shaking of a given earthquake is dependent on 3 things. 1. the energy released during the earthquake 2. the distance from the site to the hypocenter of the earthquake 3. the type of bedrock (the ground or substrate) in the place where the shaking is felt.
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The Richter magnitude scale
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Charles Richter. a logarithmic scale, based on the amount of ground displacement, measured in micro-meters (10-6 meters) measured by a "standard" seismometer at a distance of 100 km from the earthquake epicenter. 10 mm = 10-2 meters = 104 micro meters = M4 (magnitude 4) M5 quake is 40X the energy released in M4 quake
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Modified Mercalli Intensity Scale
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provides a standard for recording the experiences of people during earthquakes.
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The "intensity" of an earthquake . . .
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is defined by the amount of damage caused by the earthquake.
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most earthquakes (about 95%) occur along plate boundaries.
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But about 5% of all earthquakes occur within plates, and are termed intra-plate earthquakes.
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New Madrid, MO.
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The largest and most significant zone of intra- plate earthquakes in the U.S. is located in the area where Kentucky, Tennessee, Arkansas and Missouri meet
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why does an east coast earth quake spead out more
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the crust in the eastern US is relatively old and cold and rigid, compared to the crust beneath the western US, which tends to be somewhat hotter and less rigid.
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All else being equal, which building would more likely survive a large earthquake?
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one whose foundation is built on an exposure of granite bedrock
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Liquefaction
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occurs when wet sediment loses all of its strength and liquefies as a result of seismic shaking.Sand-blows or mud volcanoes form by the "eruption" of liquefied sand during an earthquake
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The term liquefaction refers to...
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The phenomenon of wet sand behaving as a liquid during an earthquake.
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Tsunamis
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massive wave of water capable of traveling at high speeds across oceans in a matter of hours. These massive waves may be produced by (1) meteoric impacts, (2) landslides, (3) volcanic eruptions, or (4) earthquakes.
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Tsunami waves typically form as a secondary result of _____.
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A. Landslides B. Earthquakes C. Volcanic eruptions D. Meteor impacts E. All of the above
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Earthquakes formed by slippage along a(n) ______ plate boundary are the most common cause of tsunami waves.
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subducting
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Indian Ocean/ Asian Tsunami
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230,000ppl. triggered by a 9.3 quake on plate boundary- 2nd largest ever recorded. 8-10 min of ground movement (longest observed)
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Earthquake Early Warning systems...
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Are currently being tested by the USGS.
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Magma
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Magma is molten rock mixed with dissolved gases (H2O and CO2) (under ground)
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Lava
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magma that is on the surface of earth
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Magma Viscosity
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determines erputive style of the volcano
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High Viscosity (thick magma)
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= explosive eruption
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low viscosity
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lava flows
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80% of terrestrial volcanism occurs at convergent plate boundaries (NOT including volcanoes on the sea floor)
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There are approximately 400 active volcanoes at convergent boundaries, erupting about 1 km3 of volcanic rock every year.
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Shield volcanoes
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are the largest of the common types of volcanoes on Earth. have a low profile because they are composed almost entirely of basalt and low viscosity-flows easily
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cinder cones
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smallest volcanoes. relatively steep sides and an often large crater at the summit. composed of lava, volcanic ash, and scoria.
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Stratovolcanoes (convergent)
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are intermediate in size between the shield and cinder cone types. large and steep-sided- formed by a mixture of lava & pyroclastic mat. commonly erupt a wide variety of different melt compositions and temperatures over a very long lifetime (many thousands of years) and in many different eruptive episodes.Stratovolcanoes present the greatest potential danger to life and property, because they commonly erupt explosively. (These are the majestic volcanoes commonly seen on calendars and on Discovery Channel documentaries).
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Mafic, or basaltic, lava erupted from shield volcanoes on Hawaii typically produce __________ .
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A. a'a' flows B. a cinder cone volcano C. pahoehoe flows D. layers of ash and pumice E. answers A and C
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Which of these statements is TRUE? Cinder cone volcanoes are...
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Can form very quickly and may not remain active very long.
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volcanic dome
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Small plug of very thick (viscous) lava at the crater of a volcano. Felsic lava does not flow like basaltic lava. del low temperatures.
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A large, flat volcano consisting of layers of basaltic lava is a ____________.
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shield volcano
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Hawaii
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interplate volcanoes. hot spot in deep mantle. plate moving towards northwest. hawaii is expanding.
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Which of the following is NOT a location where volcanoes form?
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Along the continental shelf
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Pyroclastic flow
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debris on fire
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Volcanic ash consists of __________. An avalanche of hot ash flowing down the flanks of a volcano is known as a(n) ____________.
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tiny shards of glass / pyroclastic flow
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Lahar
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floods of mud and muddy water produced during and after a explosive volcanic eruption that produces large volumes of pyroclastic debris (ash, tephra, etc.). Mt. rainier in danger forming a lahar easily.
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A __________ can form when ash from a volcanic eruption mixes with water (often from melted snow).
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Lahar
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Volcanic Gases & Limnic Eruption: Lake Nyos, Cameroon
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trees and wildlife may be killed by voluminous emissions of CO2 through the soil.
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A limnic eruption is the result of...
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Sudden release of CO2 gas
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Meteoroid
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tiny piece of space dust (chunk of matter) that is tiny-> .6 of a mile range. up in space
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Meteor
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a streak of light in the night sky that results when a meteoroid hits the earths atmosphere & friction causes the meteoroid to melt/vaporize/explode. a very large meteor=fireball/bolide
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Meteorite
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A natural object of extraterrestrial origin (meteoroid) that survives passage through the atmosphere and hits the ground. doesn't burn up in atmosphere. (Hoba West largest meteorite)
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Asteroid
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rly big meteorite 1km-1000km range. orbit the sun in asteroid belt bt mars and jupiter.
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Planetoid
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larger than asteroid
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Iron Meteorites
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rep the core of the earth. rare. very shiney (5.7%). represent earths core.
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Stoney-Iron Meteorites
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very rare. (1.5%)
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Stoney meteorites
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very common (92.8)
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achondrite meteorites
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represent earths crust and mantle.
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A shooting star is actually a...
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streak of light
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Iron meteorites are thought to represent the _____ of a differentiated planet.
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core
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Frequency of Impactors
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the smaller the size, the more chance it has to occur.
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The asteroid impact that occurred 65 mya is thought to...
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Be one of the causes of the extinction of dinos.
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Evidence for the K-T impact is demonstrated by...
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A. A high concentration of the element Iridium B. Tsunami deposits in North America C. Occurrences of shocked quartz D. All of the above
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Asteroid Impact
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1-in-200,000
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One 10km Meteorite...
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• Energy release: 100 million Megatons (5 Billion Hiroshima bombs!) • 100 trillion tons of debris into the atmosphere (Impact Winter) • Massive Sea Wave if at sea, Acid Rain =; sulfates • Evidence from the Moon suggests this should happen every 50-100 million years ...
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