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179 Cards in this Set
- Front
- Back
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What is a flood?
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When normally dr areas of land become inundted.
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What is the most common way a flood occurs?
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Excessive amounts of overland flow cause discharge to increase to the point that a river can no long contain its flow and the river overflows.
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What is a floodplain?
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Any area defined as being susceptible to being inundated.
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True or False
Hydrologists use the number of fatalities or property damage as a way to quantify the severity of floods. |
False.
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What is a Flood Stage?
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The height at which a river begins to overflow its banks.
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What is stream discharge?
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The amount of water flowing past a given point over some time interval.
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Floods are particularly difficult to predict because?
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They are dependent on specific weather events that have high amounts of natural variability.
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What is a recurrence interval?
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The frequency a particular river or body of water can be expected to flood.
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What is percent probability?
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The percent chance of a flood taking place i any given year.
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What are the natural factors that affect flooding?
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-The kind of precipitation event
- Ground Conditions -Vegetation Cover |
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The potential for flooding is proportional to what?
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the internsity and duration of the rain
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What is infilitration capacity?
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The ability of the ground to absorb water
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Why is the infiltration capacity so important?
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It tells us how easily water is forced as overland flow.
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How does vegetation cover affect floods?
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Higher vegetation rates mean less water reaches the ground, and how easily it can flow.
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What are the types of floods?
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-Flash Floods
-Downstream Floods |
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What is a downstream flood?
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A flood where a river leaves its channel farther down in its drainage basin, flowing into the floodplains.
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How have humans affected flooding?
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-Removal of Natural Vegetation
-Destruction of Wetlands -Construction Activity -Urbanization |
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What is sediment pollution?
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Movement of excessive sediment of the landscape into the drain areas.
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How do wetlands prevent flooding?
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It reduces the ability of the environement to absorb water from floods.
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What are culverts?
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Pipes used to discharge flowing water.
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What are the techniques to reduce flood impact?
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Dams
Artifical levees Channelization Retention Basins Erosion Controls Wetlands Restoration |
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How can scientists regulate a river flow?
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raising or lowering the resevoir of water.
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When is water added to the resevoir of a dam?
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When water levels are high.
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How do artificial levees work?
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Putting up barriers, either made of land or made of rock, that will prevent flooding into floodplains.
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What is the drawback of levees?
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They send water that would otherwise overflow even further downstream, causing more flooding downstream.
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How are levee failures commonly triggered?
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When water flows under the levee.
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What are retention basins?
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Depressions built into the ground that restricts water flow with a culvert.
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How is the severity of a flood quantified?
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discharge or stage.
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What are ocean currents?
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The physical movement of water molecules from one location to another.
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What is a tidal range?
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The difference between the high points of high tide and low tide.
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How are water waves characterized?
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Both the distance between successive crests and the difference between crests and troughs.
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What is wave refraction?
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the progressive decrease in velocity along the length of the wave as it reaches shore.
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Where do hurricanes develop?
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Over large tropical zones with low-pressure disturbances.
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How do hurricanes form?
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Low pressure disturbances become amplified into rotating storms. As evaporation occurs, warm humid air begins to rise, and large quantities of heat are removed from the ocean. The rising air mass cools and the energy absorbed is turned into the atmosphere, producing storms.
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What is the eyewall?
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the wall of clouds surrounding the eye
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Why is the hurricane's spinning important?
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it enables the storm to draw even greater amou nts of energy from the ocean.
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How can hurricanes weaken?
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Encountering upper-level winds, cooler waters, or coming ashore.
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What scale is used for hurricanes?
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Saffir-Simpson Scale
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What happens as air pressure within the eye decreases?
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Wind speed increases.
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What are the two kinds of floodplain?
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Legal and Geological
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What is a geological floodplain?
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Flat areas next to rivers
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What are legal floodpains?
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All land at risk of flooding
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What causes floods?
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volcanism, earthquakes, warm spring, hurricanes, and sustained rainfall
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What gives rivers their baseflow?
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Underground water from sediment
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What is stage?
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height of water above the datum
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What is discharge?
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velocity of water and dimensions of channel
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what is lag time?
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time between rain beginning and peak of discharge
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Rivers are part of greater network of rivers known as a ___.
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drainage basin
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What are the two kinds of PI floods?
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Upstream and Downstream
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What are the types of Earthquakes?
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1. Magmatic
2. Tectonic. |
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What does Stress mean?
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amount of force applied to a material
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What does Strain mean?
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Deformation from stress
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What is the elastic limit?
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the amount of strain that can be accumulate before fracturing or deformation.
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What is the elastic rebound theory?
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Explains that the occurence of earthquakes is related to when a force acts on a rock body, forces it to deform, reach an elastic limit, and ruptures.
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When rocks return to their undeformed states, they are known as a
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rebound.
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The sudden release of strain along a fault can alter what?
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The distribution of strain on other faults, producing aftershocks.
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Why do earthquakes only occur near the crust?
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The heat of the Earth inside the crush keeps rocks too hot to rupture.
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What is a magmatic earthquake?
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When magma forces its way up through crustal rocks.
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What are seismic waves?
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Vibrational waves that travel through solid earth materials.
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Where is the highest point of energy during an Earthquake?
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The epicenter.
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What are body waves?
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Waves in the Earth's interiro.
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What are surface waves?
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Waves on the land from earthquakes.
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What way do P waves move?
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ThThe same direction as the wwave, or parallel.
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What way to secondary waves move?
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Perpendicularly.
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Which kinds of waves back and forth?
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Rayleigh waves.
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What is the Mercalli intensity scale?
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Earthquakes rated based on a set of observations most humans could OBJECTIVELY report.
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What is the Richter magnitude scale?
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Noticing that the distance between stations is varied, this scale attempts to include and calibrate for the distance traveled to the scale.
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What are 4 ways to monitor volcanos?
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1. Gas measurements
2. Gas concentrations 3. Inflation on volcanoe's surface. 4. Groundwater temperature. |
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What kind of rock material would make seismic waves travel slower?
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Loose rock material.
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What is inertia?
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An object's aversion to move.
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What is a lahar?
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A flow of ash, rock, and water.
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What factors affect stress?
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Composition
Temperature Strain Rate |
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How deep is the Oceanic crust?
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4-7 miles.
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How deep is the Continental Crust?
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19 miles
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What temperature is crustal rock?
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Cool
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What are earthquakes categorized in?
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Seismic waves
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How do we measure Earthquakes?
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Seismic wave measurements
Seismograph Seimology measuring ground motion |
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What wave resembles a slinky?
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S-wave.
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What kind of rock material would make seismic waves travel slower?
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Loose rock material.
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What is inertia?
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An object's aversion to move.
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What is a lahar?
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A flow of ash, rock, and water.
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What factors affect stress?
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Composition
Temperature Strain Rate |
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What did Wagner do?
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Used fossils to show that the Earth was definitely moving
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What is the Lithosphere made of?
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Crust AND upper mantle.
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What evidence do we have that oceanic crust is subducting?
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Earthquakes
Volcanoes. |
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Earthquakes are a natural consequence of what?
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The Earth's tectonic plates
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What is the biggest cause of death during earthuakes?
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Structural failure
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What kinds of structures may fail during an earthquake?
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Homes, factories, highways, bridges, and damns.
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What is unreinforced masonry?
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Brick or stone bound with mortar, surrounding a wooden frame.
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What is Natural Vibration Frequency?
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the frequency buildings will vibrate at
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What is ground amplification?
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Ground resonating with a wave causing more movement.
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What happens to esedimentary basins with earthquakes?
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Amplification can occcur.
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What are the Secondary Earthquake Hazards?
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Liquefaction
Land Surface Disturbance Fires Tsunamis |
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What are the two kinds of Earthquake prediction?
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Long-term and Short-term
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What are Earthquake Precursors?
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Phenomena occuring right before Earthquakes.
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What are some Earthquake Precursor examples?
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1. Increase in foreshocks.
2. Slight swelling of ground surface. 3. Decreased electric resistance 4. Fluctuating water levels in wells. 5. Increased radon gas concentration in water. 6. Radio signals generating. |
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Why can't Earthquake Precursors always be used to predict Earthquakes?
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With the exception of foreshocks, none of the precursors ONLY happen with Earthquakes.
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What is a seismic gap?
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Sections of an active fault where strain has not been released for an extended period of time.
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How have scientists measured Earthquakes that predate our records?
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Looking within sediment rock.
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How can we reduce Earthquake risks?
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Seismic Engineering and Early Warning Systems.
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What kinds of seismic engineering help reduce damage from Earthquakes?
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Cross bracing, shear walls, base isolation.
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What is base isolation?
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Using rubber dampers between the structure and its foundation.
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How do we retrofit buildings with Earthquake defense?
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Cross braces and rubber base isolation.
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Which kind of wave travels faster?
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P waves.
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Which wave hits first?
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P waves.
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How can P waves be used to warn against earthquakes?
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They are less damaging and are faster than S waves.
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How can a few seconds be used for warning against Earthquakes?
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Shutting down gas lines or trains.
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When do the majority of tsunamis form?
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During subduction zone crustal plate movements.
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Who first noticed puzzle-like nature of Earth's continents?
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Magellan.
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Who first circumnavigated the Earth?
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Magellan's crue.
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Who explained why the continents looked like puzzle pieces.
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Wagner in 1915.
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How was testing of plate tectonics continued?
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1980s- Satellites
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Describe the differences between the Oceanic and Continental Crust?
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Oceanic is much heavier and it sinks when pushed up against the Continental crust, keeping the world from expanding.
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What kind of evidence do we have that oceanic crust is subducting?
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Volcanoes and Earthquakes
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Why do tsunamis get so big?
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As the tsunami reaches land, it is pushed up and gets taller
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How are water waves similar to seismic waves?
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They cause localized movement of particles AND transfer energy.
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What two kinds of force do water waves require?
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Disturbing and Restoring
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What is a Disturbing Force?
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A source of energy that causes water waves to move.
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What is a Restoring Force?
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A force that acts to restore the ocean surface to a flat state.
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What is the primary restoring force?
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Gravity
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What are the high points and low points on a wave called?
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Crest- high
Trough - low |
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What is the wavelength?
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Distance between two crests.
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What is the time passing between each crest?
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The Period
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How do you calculate the speed/celerity of waves>
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Length over Time
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When do waves break?
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When the depth becomes less than 1.3 times their height.
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How are water waves classified?
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Length and Depth of water.
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What is a Deep Water Wave?
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A wave wit the depth equal to or greater than half its length.
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What is a transitional wave?
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A wave whose depth is between Shallow and Deep.
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What are the explanations for shapes of volcanoes?
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Type of Magma
Type of Eruption Water vapor in the lava |
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Magma is ____ the Earth's crust.
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below
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Viscosity is a ____ in the morphology of a volcano?
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major factor
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What is the chemical name for silica?
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Si O2
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What kind of magma has low amounts of SiO2?
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Basalt
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Andesite is common with ____.
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stratovolcanoes
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Basalt is common with ___.
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shield volcanoes
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Rhyolite has extremely ____ viscosity.
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high
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What is a "hazard"?
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A source of danger.
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What is a "risk"?
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the possibility of loss or injury
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What are some hazards of Shield Volcanoes?
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extensive magma flow
heat fire gases mass wasting |
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What are some hazards of Strato-Volcanoes?
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heat
pyroclastic flow gases lava flows ash |
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What are some risks of volcanoes?
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-Loss or damage of property
-Loss or damage to infrastructure -Health issues |
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What kind of health issues risk can come from volcanoes?
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respiratory
injuries death |
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What is science?
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the process of explaining the logic and operation of the world.
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What is a pattern?
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an event that is observed repeatedly and consistently
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What is the scientific method?
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a process in which the physical world is examined in a logical manner
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What are the types of volcanic cones?
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cinder
shield composite |
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What are cinder cones?
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small features that form when lava is ejected into the air and cools around the vent.
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What is a shield volcano?
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very large volcanoes made of lava flaw.
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What is a composite cone also known as?
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A stratovolcano.
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What are some attributes of strato/composite volcanoes?
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Steep Slopes
Explosive Eruption Quite small High viscosity lava |
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What is a crater?
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a circular depression that forms around the vent
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What is a caldera?
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a circular depression, but it forms after the eruption when rocks in the subsurface collapse.
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What forms calderas?
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large volumes of magma are ejected from small magma chambers
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What are some factors in which humans respond to potential volcanoes?
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Frequency of eruptions
Availability of habitable living space. |
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When can hazards of volcanoes happen?
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Anytime, even if no eruption has occured.
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What factors control how lava will flow?
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Slope of the land surface
Volume of lava being emited Lava viscosity |
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What kinds of things can be done to control lava flow?
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Explosives, earth barriers, and continual freezing of oncoming lava.
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What is the average speed of pyroclastic flows?
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50 miles an hour
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What are some of the hazards of ash?
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Mechanical things breaking
Inhalation Water contamination |
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What is a volcanic landslide?
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ARocks, snow, and ice moving rapidly downslope.
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What is a volcanic mudflow?
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a mixture of ash and rock that contains a lot of liquid water.
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When do volcanic mudflows form?
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Loose ash is picked up by moving water from rain or thawed ice.
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What hazards arise from volcanic gases?
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They are hot and burn people
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How are tsunamis caused by volcanoes?
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explosive eruptions
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Why do people live near volcanoes?
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limited availability of land
fertile soils economic opportunity |
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What can society do to reduce volcanic risks?
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Monitor volcanic activity and evaluate potential for eruption.
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What are the predictive tools for use against volcanoes?
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Geologic History
Topographic Changes Seismic Monitoring Monitoring Volcanic Gases Geophysical or Groundwater Changes |
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What is an example of a Topographic change?
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Volcano inflation.
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What is a magmatic earthquake?
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when magma forces its way through crustal rocks.
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What is a volcano?
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The accumulation of extrusive materials around a vent through which lava, gas, or pyroclastics are ejected.
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Describe Cinder Cones
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Small features, form when lava is ejected into the air and cools into cinders which accumulate around the vent.
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Describe Shield Cone volcanoes.
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Exceptionally large, made from lava flow.
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Basaltic lava has a very _____.
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low viscosity
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Composite cones are also known as _____.
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strato-volcanoes
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Describe Composite Cone volcanoes.
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Erupt explosively, quite small, high viscosity lava, steep slopes.
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Hawaiian islands are part of ____.
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an exceptionally long chain of volcanic islands.
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Yellowstone volcanoes generate ____ .
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large amounts of pyroclastic material and few lava flows.
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Yellowstone volcano eruptions are ____.
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Explosive, and cataclysmic.
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What is a "Crater"?
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A circular depression that forms around the vent where the material is being ejected to from.
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