Unit 3 Flashcards
Explain the differences between creep and slump in terms of the mechanisms by which the material moves
creep=flow (slow, downward) caused by moisture changes
slump=slide (downward, outward) large mass slides from point of failure caused by oversaturation
What are some features of bedrock that we should try to understand in order to assess the potential for mass wasting?
rock type, faults (parallel), veins of different material (weakness), taluses indicate history off mass wasting, slope that is too steep, water movement through rock
Layering and weakness within a snowpack can be a significant contributor to the potential for avalanches. Describe some of the ways that layering and weaknesses can develop.
-when snow of different properties (temp, strength, size, type) layer
-when snowcovers are created by different exposures (thickness, temps, winds, moisture, precipitants, time, ground deformities)
-wind can create unstable slopes and slabs
-formation of hoars (layers of weak ice by cold moist air crystalizing)
What are the advantages/disadvantages of cut-and-haul?
Moving the material away to lesser-sloped area
More expensive
What are the advantages/disadvantages of cut-and-fill?
Wider flat surface
Road between two slopes, lower portion less integrity from weaker, less compact nature
How is the albedo of Earth surfaces significant to weather systems and climate change
-determines how much sun energy is reflect back to space
-as earth heats up, albedo factors melt
-the earth absorbs more radiation causing it to heat more
Why do tropical storms not normally develop within 500 km of the equator?
that is were the forces of the Corialis effect are significant enough to facilitate a strong cyclone
What is a storm surge?
when water levels rise quickly and push onto a shoreline due to the strong winds from a hurricane
How do storm surges form?
-wind (larger sea surface, higher wind)
-low barometric pressure (atmospheric bulge and enhanced wind)
-interaction with coastal features (narrower and shallower features = higher the surge)
Explain the possible role of climate change to the development of debris flows and mud flows in British Columbia
altering weather patterns (glacial melt and increased precipitation) = more water on landscapes
forest fires (burning up vegetation) = instability and oversaturation of the ground.
What evidence is there of past lahars at Mt. Rainier?
-Written and verbal record
-geologic record
What geological evidence is there of past lahars a mt. rainier?
-deposits in the layers of earth (e.g. tephra)
-distinct land formations (e.g. craters, canyons
What is the risk of future lahars at Mt. Rainier?
-evidence of previous debris paths show how far-reaching lahars in this area are; towns currently reside in known paths
-repeated occurances of lahar history
-terrain conditions cause area to be vulnerable (surface water, clay, weak slopes, ice, loose material)
What is the US Geological Survey’s program for real-time detection of lahars called?
Automated Lahar Detection System (ALDS)
how does the US Geological Survey’s program for real-time detection of lahars work?
-acoustic flow monitors (AFM) placed in frequented river valleys
-AFM data relayed through radio telemeter to computer at Cascades Volcano Observatory
-analyzed by computer for significance
-relays alert to Cascades Volcano Observatory
-Cascades Volcano Observatory alerts relevant parties
explain how people living in communities around the mountain should respond to lahar warnings
-be proactive (knowledge, plan, supplies, evac protocol)
-stay off valley floor, seek higher ground (50ft+)
-stay out of lahar path
-seek shelter
-stay put if not in danger
What process forms a thunderstorm?
Complex interactions between moisture levels and varying temperatures in troposphere
What conditions are needed for a storm to develop?
-Masses of warm, moist air to be covered by cooler and drier air
-moist, warm air to be forced up causing condensation (thus clouds)
What steps and processes are involved in storm formation?
Moisture condenses, latent heat is released, surrounding air warms and temperature gradient is created. Warm air up, cool air down. Water droplets form and fall (or rise and freeze)
Which stage of a storm creates the most storm activity?
Mature stage
How are thunderstorms classified?
max speed
size of hailstones
production of tornados
What constitutes a storm being defined as “severe”?
Tornado formation
90km/h+ winds
OR
1.5cm+ hailstones
What special condition is necessary for a severe storm to form?
VERTICAL WIND SHEAR
strength of VWS determines severity of storm
What types of severe storms are there?
Mesoscale convective complexes (most common, cluster of circular storm cells)
Squall lines (lines of singular of storm cells up to 500km)
Supercell (smallest, most dangerous and violent, produce large tornados)
What are drylines?
Air mass boundaries with varying moisture contents
What conditions are necessary for a tornado to form?
very different atmospheric pressures within a small area
What are the four stages of a tornado?
Organizational
Mature
Shrinking
Rope
Describe the organizational stage of a tornado.
-Rotational trajectory begins (from heavy wind shear)
-Rotating air gains horizontal tilt (from cycling of temp. grad.)
-Funnel forms on ground (from rotation of wall cloud)
Describe the mature stage of a tornado.
Upper and lower funnels meet
Describe the shrinking stage of a tornado.
Funnel narrows and tilts (from reduction of warm, moist air)
Describe the rope stage of a tornado.
erratic behavior (from downdrafts and updraft interacting)
