GEOS1002 Final Exam
As dictated by current restrictions, what is the max amount the level of a 100-yr flood can be encroached (raised) as a result of building or development?
0.3 meters
A study of over 8,000 US dams by the Army Corps of Engineers indicated that what proportion of the dams were unsafe?
1/3
The first tiltimeters were simple levels made w/water tubes _____ long.
25 meters
Which material is most likely to move as a translational slide?
3-meter thick soil over bedrock
What is the approximate lowest depth of a flowing stream that is dangerous to drive through?
30 cm (1ft)
How long before a flood can someone purchase insurance from the National Flood Insurance Program? (What is the waiting period between buying flood insurance & being able to file a claim?)
30 days
Hurricane Ike of 2008 was the _____ costliest tropical cyclone on record in the US.
4th
How fast do tornadoes move along the ground?
50-80 km/hr
What causes a cold front?
A cold air mass moves in under a warm air mass.
Following the May 1980 eruption of Mount St. Helens, Washington, thousands of trees lay on the ground, all parallel to one another. Why?
A lateral blast at the beginning of the eruption blew them all down.
Freezing rain (ice storm) occurs under which of the following scenarios? (Note that for this question, cold air refers to air w/a temp below freezing)
A layer of cold air above warm air which lies above a shallow layer of cold air
Which of the following is NOT distinctive about a cloud that might develop a tornado?
A shallow cloud that extends over a large horizontal distance w/a cauliflower or cotton ball-like top.
What does a supercell look like on a radar image & in what part of the storm would a tornado be expected?
A supercell is shaped like a triangle pointing toward the East w/a hook-like appendage extending from its front corner, & the tornado would be expected within this appendage.
What local circumstances raise the height of a storm surge onshore & increase its impact close to the beach?
A surge moving into a bay funnels the water & raises surge
What is a daylighted surface/layer?
A weak layer, sloping down toward a road cut or hillside at a somewhat gentler slope than the hillside
Which is the best detection device to warn people of an already-moving debris flow?
Acoustic flow monitor
The main factors that affect the chance that a slope will fail in a landslide do NOT include:
Age of the slope
Why are the skies clear in the eye of a tropical cyclone?
Air is descending; warming & drying as it descends
Why does a parcel of air get cooler as it rises over a mountain?
Air w/a certain amount of heat expands as it rises & in doing so expends energy & cools.
Which of the following is LEAST important factor for determining the risk of a snow avalanche?
Angle of the sun in the sky
If a 100-yr floodplain was flooded in 2016, when should we expect the next 100-yr flood?
Anytime
Why does a stream bottom erode more deeply when its water level rises in a flood?
As the water level rises, the water velocity increases, allowing it to carry more sediment.
Why are the deposits of streams graded w/the largest boulders or pebbles at the bottom?
As water slows after a flood, the largest boulders drop out first.
Volcanic mudflows are caused when which of the following combine?
Ash & water
What is a tuff?
Ash after deposition forms a rock
Where in a tropical cyclone is the atmospheric pressure lowest, and where is wind speed highest?
At the center of the storm in the eye, just outside the eye in the eyewall
Which months comprise the typical peak (time of greatest storm activity) of the tropical cyclone season in the Atlantic, and why then?
August-September bc it takes all summer to warm the ocean
What is the greatest danger (causes the most deaths) from a tornado?
Being struck by flying debris.
Three Sisters are located just west of...
Bend, Oregon
Human-built dams may directly fail for all of the following reasons EXCEPT:
Build-up of sediment behind the dam
What is in water in the ground that helps it dissolve limestone?
Carbonic acid formed from CO2 in air combining w/rainwater.
What effect does the wind NOT have on buildings during a tropical cyclone?
Causes roofs to collapse into a building
Which region has the highest density of lightning or thunderstorms on Earth?
Central Africa
Where do tropical cycles striking North America NOT originate?
Central Pacific Ocean, near equator
What is the best way to avoid a mudflow?
Climb up the valley wall
What creates the electrical charges in clouds that characterize lightning storms?
Collisions between ice particles of different sizes in the presence of liquid water & subsequent separation of the ice by the cloud updraft
Which way is the flow through tropical cyclones in the northern hemisphere?
Counterclockwise & inward toward the eye @ surface, upward outside the eye, & outward clockwise @ the top of the storm plus some downward motion in the eye
What should you do to avoid being killed by lightning if caught out in the open in a storm w/no available shelter?
Crouch down on the balls of your feet w/your feet together.
Which of the following factors does NOT influence the amount of snow that falls in a lake-effect snow event?
Depth of the lake
In contrast to an old ash-flow deposit, an old ash-fall tuff does NOT include which of these?
Differences in thickness based on valleys & hills
Which weather-related hazard has led to the collapse of civilizations & war?
Drought
What weather conditions are most likely to foster the formation of sinkholes?
Dry weather bc that lowers the water table so the cavern roofs are not supported & may collapse
Where does a tropical cyclone get its energy?
Evaporation from the sea surface (latent heating)
Why does Venice, Italy have canals for gondolas and boats instead of normal streets for cars?
Extraction of groundwater below the city caused subsidence of the city below sea level.
What is a talus slope?
Fan-shaped pile of rock fragment banked up against base of a cliff
Although the Atlantic coast of North America experiences few large earthquakes, what specific other event could generate a large tsunami wave that could cause catastrophic damage there?
Flank collapse of a volcano in the Canary Islands
What is avulsion?
Flooding stream permanently leaves its old channel to form a new floodplain channel
Which of the following states is NOT susceptible to landslides?
Florida
Where in North America are sinkholes most prevalent & why?
Florida bc it is almost all limestone & has abundant groundwater.
Which CANNOT be used to recognize the action of soil creep?
Fragments of rocks that clearly came from farther upslope
Where do ppl most commonly get the material to build an artificial river levee?
From the river channel, by dredging
What shape of roof is most susceptible to being lifted off by a tropical cyclone?
Gently sloping roof w/1 slope facing toward the wind
What force contributes the most to the driving force of a landslide?
Gravity
With urbanization of the upstream drainage area, what changes can be expected in the height of the 100-yr flood?
Greater height
For a rockfall, what 2 factors lead to a greater distance of travel of the moving debris?
Greater height of fall & greater volume of falling mass
What keeps a stream flowing year-round, even though it may not rain for many months?
Groundwater flow from the adjacent ground into the stream
After a major rainstorm in a humid climate with no overland flow to a stream, why does the stream level rise almost immediately?
Groundwater seeps down to raise the water table to force older groundwater out into the stream.
Aside from flooding, what damages do NOT accompany the surge of a tropical cyclone?
Heavy sand is deposited on beaches, partly burying some homes.
What is the largest contributing factor to creating a tropical cyclone storm surge?
High winds pushing water causing it to "pile up"
What significant effects does faster forward speed of a tropical cyclone have on coastal areas?
Higher surge & less rain
What is "cohesion" as applied to slope failure?
Holding together of otherwise loose grains on a slope, often by a little moisture
What kind of material is most likely to fall in a rotational slide?
Homogeneous, cohesive materials
If you're at the beach & feel a large earthquake, what should you do & when?
Immediately run up slope as far as possible.
Where is the safest place to be in lightning storm?
In your house.
What pattern exists i the annual cost of US flood damages from 1910-2010?
Increase due to population increases & floodplain development
Why does raising the groundwater level often lead to slope failure?
Increases water pressure in the pore spaces between grains, pushing them farther apart.
Why does removal of vegetation cause more surface runoff and thus more erosion?
It permits more water to directly strike the ground and run off.
What is karst & how does it form?
Karst is the ragged landscape that results when soil is eroded away revealing limestone bedrock that has been partially dissolved.
Which of these effects on coastal areas is NOT caused by heavy rain during a tropical cyclone?
Large storm surges
What major factor does NOT control the maximum height of water downstream from failure of a dam?
Length of the reservoir upstream of the dam
If you don't have a storm shelter/basement, where is the safest place in a house to be during a tornado?
Lying in a bathtub in an interior room without windows
Which of these is NOT a Cascade volcano of western North America?
Mt. Vesuvius
In what direction do most mid-continent tornadoes travel along the ground?
Northeast
If an ash flow approaches you from across a km-wide lake, are you likely to be safe or not? Explain.
Not safe. Ash flows can cross much wider bodies of water.
What is the most dangerous location in a tsunami hazard?
On a sandy beach at the end of a bay
Which of the following is LEAST effective in mitigating the impact of tsunami?
Orient streets & buildings parallel to waves
What are oxbow lakes & how do they form?
Oxbow lakes are cut off meanders, left behind as a flooding stream takes a shorter path downstream.
95% of ______ output from the Gulf of Mexico, the largest domestic source, was disrupted by Hurricane Katrina.
Petroleum
Old landslides are NOT normally reactivated by:
Piling heavy rocks on the lower part of the slope.
1 way in which water CANNOT be removed from a wet slope that may slide is to:
Place a load on the slope to help squeeze water out of it.
Which of the following is NOT a cause increased erosion in a stream channel?
Planting native trees in the flood fringe
What human action does NOT negatively impact stream processes and cause excessive erosion?
Planting trees
Which of the following human activities would NOT contribute to desertification?
Planting trees
Which of the following would NOT cause the height of water in the ground to rise, thus increasing danger of sliding?
Planting trees
Which of the following does NOT lead to formation of sinkholes?
Pumping waste fluids into the ground for disposal
What causes caverns to form in limestone?
Rainwater dissolves carbon dioxide to make weak carbonic acid that dissolves limestone.
Which of the following is NOT a common reason cited for building large dams on rivers?
Raise groundwater levels upstream
What is often the first indication of the arrival of a tsunami at the coast?
Rapid drop in sea level
What changes upstream from a site would NOT likely lead to a higher and narrower hydrograph?
Reforestation for a Christmas tree farm
As it enters a bay, the height of tsunami wave:
Rises bc more water from each wave is forced into less space.
A big bulge sometimes slowly grows on the flank of an active Cascades volcano. Why?
Rising magma pushing it up
Other than limestone, what other types of rocks are soluble & can form cavities that collapse?
Salt & gypsum
Which of the following is NOT a feature of modern debris flow trapping structure?
Sand & mud from the floodplain
What process does NOT lead to the failure of a river levee?
Sandbagging the levee to raise its height
All of these diminish the reliability of recurrence intervals EXCEPT:
Separating different meteorological conditions or causes of flooding
Which of the following is NOT a good use for floodplains?
Shopping centers
What is the significance of a sand boil?
Sign of seepage under a levee
Which is NOT a method for recognizing the presence of swelling soils?
Since they deform elastically, the ground feels spongy or bouncy underfoot.
The main reason Santa Ana winds are warm is:
Sinking air warms by compression.
Which of the following CANNOT be used to determine the depth of a debris flow in a canyon it moved through?
Size of the boulders left by the flow
Tsunami waves nearing the open coast:
Slow down bc they drag more on the shallower bottom than in the deep ocean.
Which of the following submarine faults CANNOT cause tsunami waves?
Strike-slip faults
What are the 2 main causes of tsunamis?
Subduction-zone earthquakes & landslide into the ocean
What cause the loud boom that we hear as thunder?
Supersonic expansion of air heated by a lightning bolt
What caused the catastrophic 1997 flood along the Red River in North Dakota?
Thawing to the south of the frozen north-flowing river that backed up water behind the ice to the north
How would a hydrograph for a drainage basin change if major urban growth were to occur upstream?
The hydrograph would be higher & narrower
Why do ships in the open ocean NOT notice passage of a tsunami wave?
The long time between wave crests dictates that the wave flanks have almost no flank.
Why does earthquake shaking of water-saturated sand often lead to ground settling?
The shaking of sand leads to closer packing of the grains.
Why does the top of a rotational slide tilt back into the slope?
The slide mass rotates on a circular curving surface, so everything on it rotates backward.
Why are flash floods more common in dry climates than wet climates?
The soil is less permeable.
Why do braided streams form in a dry climate instead of meandering streams?
The stream has too little water to carry the total sediment supplied.
Which of the following statements is NOT true about the effects of mining sand or gravel from a streambed or bank?
There aren't any negative effects, the stream merely brings in more sand & gravel.
What effect do levees NOT have on a stream?
They prevent the stream or river from ever changing course.
What physical effect do most bridges have on the streams they cross?
They restrict flow on the floodplain, so water under the bridge is deeper and faster.
What are the main characteristics of soil above a limestone cavern that leads to the formation of a cover collapse sinkhole?
Thick, clay-rich, & cohesive enough to develop a large cavern before it collapses
Why are houses built close to or on the beach in tropical cyclone-prone areas generally on tall posts? (elevated off of sand)
To keep them above the level of the storm surge
Why do highway depts. sometimes pile huge boulders near the base of a sloping road cut?
To prevent slumping of the road cut by loading the toe of the potential slump
Which part of a storm is most likely to form tornadoes?
Towards the trailing edge of the storm behind the heaviest rain.
Which of the following is a difference between tropical cyclones & nor'easters?
Tropical cyclones gain their energy from evaporation from the sea surface. Nor'easters gain their energy from large temp gradients.
To prepare for a tropical cyclone, the text recommends you do all of the following except:
Turn off your appliances, including the fridge
Why does swelling clay swell, potentially increasing the likelihood of a landslide?
Water gets into the clay layers, spreading them apart.
Which of the following is LEAST likely to have a flash flood?
Western Washington state
Why is it so important to cover windows and doors w/plywood or shutters in the event of a tropical cyclone?
Wind-blown debris can easily break these parts of a structure, allowing wind & rain to get into a structure & cause much greater damage.
Why is storm damage of a westward-moving tropical cyclone generally less on the south side of the eye?
Winds are moving offshore there so the waves are smaller & water is being pushed away from the shore. The storm surge is primarily north of the eye.
As air temp rises, its ability to hold water:
increases
