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Earthquakes/Glaciers
Envir. Principles Mid-term
| Question | Answer |
|---|---|
| Formed in the earth’s crust as a response to stress put on the rock mass. | Fault |
| When exerted on a rock mass it is the force acting on the surface which may be greater in one direction than in other directions. | Stress |
| The movement of the tectonic plates provides the _____, and rocks at the earth surface break in response to the applied _____. | Stress |
| What determines the type of fault that is formed? | The type of stress |
| Three types of stress include: | Compression, Tension and Shear |
| The stress types correlate with the three main types of lithospheric ____ ________. | Plate boundaries |
| What are the three types of plate boundaries? | Compressional stress - convergent boundaries Tensional stress - divergent boundaries Shear stress - transform margins |
| Acts in a direction perpendicular to and towards a surface. | Compressional Stress |
| Has the effect of squeezing and shortening | Compressional Stress |
| The lithospheric plates are pushed together | Compressional Stress |
| Creates a reverse fault. | Compressional Stress |
| Acts in a direction perpendicular to, and away from a surface. | Tensional Stress |
| Has the effect of pulling and elongation the crust. | Tensional Stress |
| The type of fault formed through tensional stress is referred to as a “normal” fault. | Tensional Stress |
| Acts in a direction parallel to a surface. | Shear Stress |
| _____ stress has an effect similar to a “shift”. | Shear Stress |
| The resulting fault is referred to as the slip fault on Continental crust, and a transform fault on oceanic crust (Despite the different names, the fault generation is the same). | Shear Stress |
| A sudden release of energy within the earth’s crust caused by the movement of the lithospheric plates along fault margins. | Earthquake |
| What two forces occur in the fault which causes the plates to temporarily seize and suddenly release stored energy to generate an earthquakes? | Stress and friction |
| Energy that is released during an earthquake event occur in three forms: | 1. Movement along the fault. 2. Heat. 3. Seismic waves that radiate out from the source location. |
| Earthquakes occur most often along 2 types of faults? | transform fault margins and subduction zones |
| T/F: Quakes generated at subduction zones can occur at varying depths? | True |
| Less than 60 km from the earth surface is a ____ ____? | Shallow earthquake |
| Between 60 and 300 km below the earth surface ____ ____? | Intermediate earthquake |
| Greater than 300 km below the earth surface ____ ____? | Deep earthquake |
| What determines frequency of earthquakes? | The type of lithospheric plate movement. |
| Approximately xx% of all the recorded earthquakes occurs along the ring of fire. | 90% |
| Approximately xx% of the world’s largest earthquakes occurs along the ring of fire. | 80% |
| A portion of the energy released during an earthquake is transmitted to other areas of the earth in the form of ____ ______ energy. | Seismic Wave |
| A seismic wave is a _____ ______ passing through the Earth’s interior. | mechanical vibration |
| A _____ _____ elastically deforms the rocks it passes through, leaving no visible record that the event ever occurred. | seismic wave |
| Suggests that all solids are elastic within limits. | The Elastic Rebound Theory |
| T/F: The Elastic Rebound Theory states that all solids will stretch and bend then snap back when the stress is removed. | True |
| T/F: solids will not continue to vibrate like a guitar string. | False - solids do. |
| Asserts that vibrations manifest as waves and radiate outwards. | The Elastic Rebound Theory |
| What are two main types of seismic waves? | Body waves and Surface waves |
| Are seismic waves that travel through the Earth’s interior. | Body Waves |
| What are the two types of body waves? | Primary waves (P waves)and Secondary waves (S waves). |
| Have the ability to pass through solids, liquids and gases. | P waves |
| Travel through rock by generating an undulating motion. | S waves |
| Move at a higher velocity and therefore are detected first following an earthquake. | P waves |
| Cannot be transmitted through liquids or gases. | S waves |
| Cause the rock to vibrate up and down similar to a rope when one end is shaken. | S waves |
| Consist of alternating pulses of compression and expansion in the direction of wave travel. | P waves |
| Travel along or near the earth surface similar to waves along the surface of the ocean. | Surface Waves |
| Travel more slowly than both P waves and S waves, and are therefore detected last by a seismograph. | Surface waves |
| Are responsible for much of the ground movement felt at the earth surface and structural damage that occurs during major earthquakes. | Surface waves |
| P waves and S waves are reflected and Refracted when they encounter an interface separating two materials of different elastic properties. This causes? | Aftershocks |
| The location where rupture commences and an earthquake energy is first released. | Focus |
| The point on the earth surface directly above the focus. | Epicenter |
| Is the strength (amount of energy released) of the earthquake. | Magnitude |
| The greatest magnitude of an earthquake is directly related to the length of the fault where the earthquake occurred. | Key magnitude point |
| T/F: The longer the fault = the greater the potential magnitude. | True |
| The most familiar scale used to measure the magnitude of an earthquake that is a logarithmic scale. | Richter Scale |
| Assumes that an earthquake’s focus is a single point on the earth, and not a large area. | Richter Scale |
| It is the current system used by the USGS to measure earthquakes, and accounts for the fact that an earthquake may be generated over a large area. | Moment Magnitude Scale (MMS) |
| T/F: the MMS method of magnitude calculation is different than the Richter Scale, but it uses the same magnitude scale developed by Richter. | True |
| A scale of seismic intensity is a way of measuring or rating the effects of an earthquake at different locations. | Modified Mercalli Intensity Scale (MMIS) |
| T/F: Based on magnitude, but not based on the damage created as a result of an earthquake. | False - MMIS is not based on magnitude, but based on the damage created as a result of an earthquake. |
| Based on a relatively subjective scale of descriptions, and rating the intensity of an earthquake does not require any instrumental measurements. | Modified Mercalli Intensity Scale (MMIS) |
| A series of waves caused by the displacement of a large volume of water caused by a sudden change in the seafloor. | Tsunami |
| Are formed as a result of earthquakes, volcanic eruptions or landslides that occur under the sea. | Tsunami |
| Huge amounts of energy are released causing vertical uplift of the seafloor and displaces large amounts of water which eventually make their way onto land. | Tsunami |
| T/F: If the wave speed decreases, the amplitude increases to dangerous heights of up to 30 m or more. | True |
| Wave speed of tsunami at shore is approximately xx km/h. | 70 km/h. |
| An area of land that rises abruptly from the surrounding region. | Mountain |
| A succession of many closely spaced mountains covering a particular region of the earth. | Mountain Range |
| Consists of several mountain ranges that run roughly parallel to each other. | Mountain Belts |
| The process of mountain building is called “orogenesis” and occurs as a result of movement of the Earth’s crustal plates. | Mountain Building |
| Mountain building involves three stages. What are they? | 1) Accumulation of sediments. 2) An orogenic period of rock deformation and crustal uplift. 3) A period of crustal uplift caused by isostatic rebound and block-faulting. |
| Mountain belts normally contain numerous layers of _______ and of ________ rock. | sedimentary and igneous |
| T/F: These accumulations can be several kilometers in thickness. | True |
| T/F: Most of these accumulations were not originally deposited in a marine environment. | False |
| The accumulated sediments become deformed by compressional forces from the collision of tectonic plates. Which stage of mountain formation is this? | Orogenic Period |
| This compression causes the once flat sedimentary beds to be _____ and ______. | folded and uplifted (Orogenic Period) |
| When the compressional forces become greater than the rocks ability to deform, ____ occurs. | faulting (Orogenic Period) |
| Compressional forces typically result in ________ and ______ faulting. | reverse and overthrust(Orogenic Period) |
| This stage is characterized by ______ _____ because of isostatic rebound and block-faulting. | crustal uplift |
| Involves the vertical movement of continental crust that is floating in the plastic upper mantle. | Isostatic rebound (Crustal Uplift) |
| ______ removes surface materials from mountains, the weight of the crust in this region becomes progressively less and causes ____ _____. | Erosion, isostatic rebound (Crustal Uplift) |
| Isostatic adjustment also causes tensional forces to exist in a horizontal direction breaking the Continental crust into a ______ __ ______. | number of blocks (Crustal Uplift) |
| Each block moves vertically to compensate for the tensional forces producing _____. | faults (Crustal Uplift) |
| The 3 mountain types are: | Volcanic mountains Fold mountains Block mountains |
| Formed along plate boundaries where plates come together or move apart and lava and other debris is ejected on the earth surface. | Volcanic Mountains |
| Formed where plates push together and cause the rock to buckle upwards. | Fold Mountains |
| Since folding requires compression, this orogenesis occurs at _____ ______ _______. | converging plate boundaries (Fold Mountains) |
| Ocean - continental plate convergence: _____ _____ orogenesis | subduction type (Fold Mountains) |
| Continent - continent convergence: | collision type orogenesis (Fold Mountains) |
| Major mountain systems of the world are of this type | Fold Mountains |
| Up-warped mountains, formed when a block of land is uplifted between two faults as a result of compression or tension in the earth’s crust. | Block Mountains |
| The continuous movement of the earth’s crustal plates can squeeze, stretch, or break rock strata, deforming them and producing _____ and _____. | faults and folds |
| There are three major ways in which stress affects rigid rock during the mountain building: | 1) Compression (crustal shortening) 2) Tension (stretching) 3) Shear (forces parallel but in opposite directions) |
| Sudden _____ near the earth’s surface fractures rock. | stress |
| _____ are fractures along which movement has occurred. | Faults |
| Is a bend it in a rock layer caused by compression. | Fold |
| T/F: Vary in size from a few millimeters long to folded mountain ranges hundreds of miles long. | True |
| Two Main Types of folds: | 1) Anticlines (up-folds) 2) Synclines (down-folds) |
| Evidence for crustal uplift and tectonic activity (folding and faulting) can be seen in 3 ways: | 1) Fossils of marine organisms high up on mountains 2) Uplifted marine terraces 3) Surveys of uplifted benchmarks in the Rocky Mountains. |
| The down-slope movement of soil, regolith and/or bed rock masses due to gravity without the aid of a transporting medium such as water, ice or wind. | Mass Wasting |
| Incidents of mass wasting are often referred to as ______. | landslides |
| Occurs when the gravitational force acting on a slope exceeds its frictional resisting force. | Mass Wasting |
| T/F: Occurs in both terrestrial and submarine slopes. | True |
| Slope angle (slope steepness), nature of slope material (regolith), water content of the slope material and human activities are all factors that affect the rate of? | Mass Wasting |
| The accumulation of angular rock debris resulting from rock falls. | Talus |
| The maximum angle at which inclines soil material (regolith) will remain stable. | Angle of Repose |
| Triggers of mass wasting events include: | Earthquakes, Floods, Rain events, Volcanic eruptions. |
| Excessive water content causes ______. | slumping |
| Saturated material has a very small _____ of _____. | angle of repose |
| The saturated material tends to behave like a liquid because the water completely fills the void spaces between the soil grains and eliminates the grain to grain ________ _____. | frictional contact |
| Mass wasting is divided into two categories: | Slope failures Flows |
| Are sediment debris flows downslope that are mixed with water or air to form a flow like consistency. | Flows |
| is the falling, slumping or sliding of relatively coherent masses of rock or regolith. These failures result in the transporting of debris downhill by sliding, rolling, falling or slumping. | Slope Failure |
| Three basic types of slope failures: | Fall Slide Slump |
| Is a sudden vertical or nearly vertical drop of rock fragments or debris. | Fall |
| Occur suddenly. Often occur when a piece of rock on steep slope becomes dislodged and falls downslope. | Falls |
| The accumulation of fallen material at the base of the cliff is termed _____. | Talus |
| Involve a quick displacement of a mass of rock or sediment in a straight line down a steep or slippery slope without rotational movement. | Slide |
| One of the most common types of mass wasting. | Slide |
| A rotational movement of rock and/or sediment. | Slump |
| Rotation occurs _____ and _____ from the slump origin along a curved surface. | downward and outward |
| This type of mass wasting is a rupture that occurs in one location and the volume of displaced material expands from that local failure location. | Slump |
| This type of mass wasting occurs most frequently in homogenous materials and most often in fill. | Slump |
| Two main categories of Sediment Flow | Slurry flows Granular flows |
| Sediment flows that contain between 20% to 40% water content. | Slurry Flow (Sediment Flow) |
| Three main types of slurry flows: | 1) Solifluction (waterlogged movement over impermeable material) 2) Debris flows 3) Earth flows |
| Sediment flows that contain between 0% to 20% water. The flow like behaviors achieved by mixing with air. | Granular Flow (Sediment Flow) |
| Two main types of granular flows: | Creep Debris avalanche |
| Mass wasting is imperceptibly slow. Most common type of granular flow. Movement of usually less than 1 m per decade. | Creep (Granular Flow) |
| The following are examples of? Curved tree trunks. Small soil ripples or ridges on the ground surface. Bent fencing or retaining walls. Tilted hydro-polls. | Creep (Granular Flow) |
| when an unstable slope collapses and the resulting debris is rapidly transported away from the slope. | Debris Avalanche (Granular Flow) |
| 10% of the world’s land mass is covered by glaciers. | Glaciers |
| Make up 75% of the Earth’s fresh water. | Glaciers |
| Contain extensive record of variations in atmospheric gases and aerosols. | Glaciers |
| Record of variations in atmospheric gases and aerosols in glaciers include information about: | 1) Variations in CO2. 2) Oxygen content (as a means of measuring temperature in the lower atmosphere). 3) Variations in the meteoritic infall rates. 4) The occurrence of explosive volcanic activity through deposition of tephra. |
| A semi-permanent or perennially frozen body of ice, consisting mostly of recrystallize snow that moves under the pull of gravity. | Glacier |
| A huge mass of ice slowly flowing over a land mass, formed from compacted snow in an area where snow accumulation exceeds melting and sublimation. | Glacier |
| Snowflakes convert to granules of ice, whereby snowflake crystals become smaller, rounder and denser. | Formation of Glaciers |
| Snow that survives one annual year. | Firn |
| In time, snow accumulation gradually becomes very ____ so that it is not _______ by air - the resulting ice is _______ ice. | dense, penetrable, glacier |
| When the ____ of the accumulation of snow and ice become so thick that _______ forces cause the frozen mass to _____, a glacier is formed. | weight, gravitational, move |
| Most glaciers are found in regions of ____ _____ in the winter and _____ ______ in the summer. | high snowfall, lower temperatures |
| All processes through which snow or ice is added to a glacier. | Accumulation |
| Combine processes such as melting, evaporation or sublimation which removes snow or ice from the surface of a glacier. | Ablation |
| Location where glacier originates. | Head |
| The lowest end of a glacier, also may be referred to as the toe or snout. | Terminus |
| Process through which ice breaks off the glacier terminus. | Calving |
| When a glacier terminus extends further than it did previously. | Advance |
| The difference between accumulation and ablation of a glacier. The mass balance may be a deficit, surplus or equilibrium. | Mass Balance |
| Glaciers move faster in the ____ ____ than at the _____, and the ______ portion of the glacier generally moves faster than the lower portions. | central portion, sides, uppermost |
| Velocities may range from a few centimeters to a few meters per ____. | day |
| Glacial velocities dependent on the following four factors: | Temperature. Thickness of the glacial ice. Bed material. Gradient. |
| Occurs in the lower portion of a glacier as the weight of the overlying snow and ice increases. | Internal Flow (Glacial Movement, Method #1) |
| As the compacted frozen mass moves, the crystal axes of the individual ice crystals are forced into the same orientation and end up with their internal plane situated in the same direction. | Internal Flow (Glacial Movement, Method #1) |
| When the glacier moves over a change in _____, such as a cliff, the brittle surface ice cracks as tension pulls it apart. The resulting cracks are called _______. | slope, crevasses |
| Is the movement of a glacier over top of the bed (substrate material below the glacier). | Basal Sliding (Glacial Movement, Method #1) |
| Occurs when a thin layer of water builds up at the ice substrate interface and acts as a lubricant to move the ice mass. | Basal Slip (Basal Sliding, Glacial Movement) |
| Occurs when ice moves and squeezes up against a large obstacle (greater than 1 m) and an increase in pressure at that point causes the ice to deform around the feature. | Enhanced Basal Creep (Basal Sliding, Glacial Movement) |
| Similar to basal creep, where the glacier encounters a small obstacle (less than 1 m) and rather than deforming around the obstacle, the ice melts and re-freezes on the leeside of the obstacle where the pressure is lower. | Relegation Flow (Basal Sliding, Glacial Movement) |
| Is one of the greatest influences on the type of movement exhibited by a glacier. | Ice temperature |
| This form of glacial movement is more efficient as a process if water is present at the base of the glacier allowing lubrication. | Basal sliding |
| This form of glacial movement is more apt to occur in more temperate locales. | Basal sliding |
| This form of glacial movement is more apt to occur where there is an absence of water at the base of a glacier, in colder climates. | Internal flow |
| Glaciers that are located in temperate locales are called: | temperate glaciers |
| Glaciers located in colder areas, where the mean annual temperature is below freezing, is commonly referred to as a? | polar glacier |
| Are named for the bowl-like hollow area they occupy which are called cirques. | Cirque Glaciers |
| Typically they are found on high mountain sides and tend to be wide rather than long in formation. | Cirque Glaciers |
| Often serve as the source for a valley glacier. | Cirque glaciers |
| Commonly originating from mountain glaciers or ice fields, Valley glaciers appear to “spill” down the valleys. | Valley Glacier |
| They are often long, extending beyond the snow line of a mountain and occasionally reaching sea level. | Valley Glacier |
| Glaciers located in fjord valleys are called... | Fjord Glacier |
| Often give rise to icebergs that break off and float away. | Fjord Glacier |
| Occur when steep valley glaciers move into relatively flat plains where they start to spread out into bulb-like lobes. | Piedmont Glacier |
| Are enormous continental masses of glacial ice and snow expanding over 50,000 km². | Ice Sheet |
| Exhibit a radial flow pattern. | Ice Sheet |
| Ice sheets account for approximately xx% of the world’s glacial ice, and about xx% of the earth’s freshwater. | 95%, 70% |
| Under the weight of an ice sheet, the Earth’s crust underneath the glacier may be ________ into the asthenosphere. This process is known as ______ ________. | compressed, isostatic depression |
| Are mini ice sheets that cover less than 50,000 km². | Ice Caps |
| They generally form in polar and sub polar regions that are relatively flat and high elevation mountainous areas. | Ice Caps |
| Similar to ice sheets, icecaps usually display a ______ flow pattern. | radial |
| Occur when ice sheets extend over the sea and float on the water. | Ice Shelves |
| They range in thickness from a few hundred meters to over 1000 m | Ice Shelves |
| Are replenished by land-based glaciers and lose ice when large pieces of the shelf break off; this loss results in icebergs. | Ice shelves |
| The last Canadian ice sheet reached the maximum size and thickness approximately? | 20,000 years ago. |
| This ice sheet was called the ________ ice sheet. | Laurentide |
| The last glacial period occurred from about _____ to ____ years ago. | 110,000 to 10,000 |
| This glacial period is referred to as the __________ glacial episode. | Wisconsin |
| This ice sheet WAS irregular in shape, with several protruding finger-like lobes located in the Great Lakes area. | the Laurentide ice sheet |
| The Laurentide ice sheet had a maximum thickness of approximately _______, while Southern Ontario was covered by about _______ of ice. | 3000 m, 1000m |
| The Laurentide ice sheet retreated fairly rapidly, starting around ______ years ago. | 15,000 |
| Isostatic rebound is a slow process which in the Great Lakes occurs at a rate of about _____ per ______. | 7.5 cm per century |
| Carried by glacial ice, a piece of rock that deviates from the size and type of the rock native to the area in which it rests. | Glacial Erratic |
| Is a long, winding ridge of stratified sand and gravel. The internal makeup of an Esker is typically comprised of stratified sands and gravels. | Esker |
| Frequently several miles in length and, because of their peculiar uniform shape, somewhat resemble railroad embankments. | Esker |
| When the ice sheet was retreating, melt waters within the glacier mined a tunnel through the ice. This tunnel could have been anywhere throughout the ice sheet. THis tunnel formed what land feature? | Esker |
| Water as the agent of transportation results in sediment deposition that is a ____ ____ ____ (or ____ ____ ____). | well sorted material/poorly graded material |
| Any glacially formed accumulation of unconsolidated glacial debris (soil and rock) which can occur in currently glaciated and formerly glaciated regions. | Moraines |
| May be composed of silt like glacial flour to large boulders. | Moraines |
| Two types of moraines: | End moraines Ground moraines |
| Considered an interlobate moraine. | Oak Ridges Moraine |
| It was formed between two large ice slopes at the leading edge of the continental glacier. As a result twice as much material was deposited. | Interlobate moraine. |
| Melt waters from these lobes reworked the till, sorting and depositing material. For this reason the Oak ridges moraine has many pockets of _____ and ______. | sand and gravel. |
| This fluvioglacial land-form occurs as the result of blocks of ice calving from the front of a receding glacier and becoming buried partially to wholly by glacial outwash. When the calved ice block melts, ___ ____ are left in the sandur. | Kettles, kettle holes |
| Substratum deformation, meltwater sediment deposition within cavities or meltwater erosion are said to be possible causes of this feature? | Drumlins |
| T/F: Drumlins do form in all glaciated areas. | False |
| When the till in a drumlin was deposited the material was ______ ______ (____ ____). | poorly sorted (well graded) |
| Drumlins in a drumlin field typically have a _____ _______. | parallel alignment |
| This parallel alignment of drumlins indicats that the ___ _____ was the ___ throughout this area. | ice motion, the same |
| The tapered end of a drumlin points in the direction of the glaciers direction of _____. | travel |
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