Geology 2104 VT - Test 3 (Stress & Strain, Structure, Earthquakes, Slope Stability)

All topics for Test 3 in GEOS 2104 at Virginia Tech with J.A.Hole. I made this my first semester and hope it’s somewhat helpful. Best of luck!

What is stress and how is it different from force?

Stress is force per unit area. It is a force distributed across a surface.

What is normal stress?

Normal stress is from force applied perpendicular to the surface - ‘normal’ to the surface. This is the vertical component of force.

What is shear stress?

Shear stress is from force applied parallel to the surface; it slides across/slips. This is the horizontal component of force.

What is principal stress? Define its coordinate system - why is it useful?

Principal stress is stress measured inside a volume of material (ex: soil, rock, steel, etc.). The coordinate system is in 3D and uses a reference cube. The cube can always be rotated to an orientation in which the cube has zero shear stress on its face.

Define relative sizes of principle stress (σ1, σ2, σ3).

Principal stress results in only three normal stresses 1>=2>=3. In geoscience, 1 is most compressive (positive) or maximum compressive state.

What is pressure? How is it related to stress?

Pressure is uniform stress in every direction (1=2=3=P). Shear stress in every direction is zero (xy=xz=yz=0). Compare definitions of stress and pressure to see relationship.

What is lithostatic stress and what causes it?

Lithostatic stress is stress due to weight of overlying rock - the vertical normal stress, sometimes called overburden. Usually not equal to horizontal normal stresses.

σ=phg

p=density of overlying rock; h=thickness of overlying rock; g=acceleration of gravity

What is the orientation of the principle’s stresses in Earth’s lithosphere?

• What about at a seafloor spreading center? (horizontal extension)

• In a continental collision or subduction zone? (horizontal compression)

• At a transform plate boundary? (horizontal shear)

Usually, the orientation is vertical.

• σ1 is vertical, σ3 is in extension direction

• σ3 is vertical, σ1 is in compression direction

• σ2 is vertical

Calculating normal and shear stress on an arbitrarily oriented plane, what is the orientation of the plane where:

• normal stress is at a maximum?

• normal stress is at a minimum?

• shear stress it at a maximum?

• shear stress is at a minimum?

• plane is perpendicular to σ1

• plane is perpendicular to σ3

• zero on three plains perpendicular to σ1, σ2, σ3

• stress on two planes between σ1 and σ3

Define strain.

strain = deformation = change in size and/or shape

How is strain related to stress?

Stress (force) causes strain (deformation).

Define normal strain.

There is a change in length. Units: dimensions.

Define shear strain.

Change in angle. Units: dimensionless.

What are the characteristics of elastic strain? How big is the stress? What is the relationship with the stress? (Hooke’s Law - give an example from physics.)

Temporary, happens at a small amount of stress, occurs immediately, and stores potential energy.

Hooke’s Law: elastic strain is linearly proportional to the stress. (stress = modulus x strain ; modulus is object/substance’s resistance to being deformed elastically) Example: a spring’s change in length is proportional to the force

What occurs at the elastic limit?

Stress exceeds what the material can handle, so it becomes a permanent strain (the material breaks or flows).

Define strength.

The strength of a material is the amount of stress it can handle at breaking point. In short, the stress at point of failure. This depends on T & P.

What happens when a rock undergoes brittle strain?

Shear and normal stress are on a plane. Shear stress tries to cause a slip on the plane and break material along the plane. Normal stress increases friction against slip on the plane. In short, material breaks (permanent).

What happens when a rock undergoes ductile strain?

Also called plastic deformation. Material doesn’t crack or fracture, it flows (permanent).

For a plane that might break (brittle strain):

• does increasing the shear stress increase or decrease the chance of breaking? Why?

• does increasing the normal stress increase or decrease the chance of breaking? Why?

• Increases because it causes more strain.

• Increases chance of breaking because it increases the friction of the slip (shear stress).

Coulomb failure (don’t need to know formulae but need to be aware….)

… need to be aware that we can predict whether a rock will break and at what angle.

What is the relationship between normal stress and internal friction?

Internal and external friction (Coulomb friction) rely linearly on normal stresses.

What is the role of pre-existing planes of weakness in the brittle failure criterion above? Give four examples of geologic features that can act as planes of weakness.

They have weaker cohesion (the strength of interlocking grains), coefficient of internal friction, and angle of internal friction. Examples: fractures, bedding, foliation, and contact between rocks. (Properties are different along different directions.)

What does water under pressure do to the brittle strength of a rock?

water pressure in pores → less friction → weakens rock → lubrication

How does a solid rock flow (undergo ductile strain)? How fast? Give examples of geologic processes.

Atoms move within crystals; crystals move within rock. Moves very slow. Ex: glacier, mantle convection, folded sedimentary rocks, and sheared gneiss.

Factors that determine whether rock failure (permanent deformation) is brittle or ductile:

brittle (break) vs. ductile (flow)

_ temperature

_ pressure

_ depth

_ time (fast strain/slow strain)

Need to know strength of igneous, sedimentary, and metamorphic rocks!!! (Usually, strongest to weakest, it’s igneous, metamorphic, and then sedimentary.)

brittle (break):

low temperature, low pressure, shallow depth, fast (short time) strain rate

ductile (flow):

high temperature, high pressure, deep depth, slow (long time) strain rate

Structural geology is …

the study of the structures produced by deformation.

What are the two types of permanent strain? (Review from last topic.)

brittle and ductile

What is the role of a primary structure in structural geology? What is the most important primary sedimentary structure? (What’s its original shape and orientation?)

Sedimentary, igneous, metamorphic. Layering/bedding/strata - original horizontality → deformed.

Define strike and dip. Why do geologists measure them?

Strike is compass direction of horizontal (south) parallel to bedding. Dip is the angle downwards (steepness - west) from horizontal surface; drawn peroendic. Measured to know orientation of plane and need to measure local orientation of objects. Sometimes soil, vegetation, buildings, rivers, etc. get in the way of seeing rocks, so need to measure local orientation of objects.

What is a fracture? What kind of strain is it?

A fracture is a crack in a rock. It’s a brittle strain/deformation. There are two types of fractures: fault (fracture with motion parallel to it) and joint (fracture without motion).

What is the difference between a fracture and a fault?

A fracture is a break in a rock without significant movement or displacement and a fault is a break or crack with motion (the rock moves along the break or crack).

Imagine the angle between the principal stresses and each fracture. What relative directions does the rock move?

• An extensional fracture

• A shear fracture (=a fault - this is Coulomb failure)

• In an extensional fracture, the rock is pulled apart (this is very rare). It usually happens because of fluid pressure. Extension stress is often effective stress → fracture due to fluid pressure (ex: magma, fracking) can be intruded by magma.

• Shear fractures are (usually) called faults. It’s Coulomb failure (on one or both planes). Much more common than extensional fracture.

Define hanging wall and footwall of a fault.

Hanging wall is vertically above the feature and foot wall is vertically below the feature.

Imagine a normal fault. What direction does the hanging wall move? In which stress setting does this occur? At which plate boundary does the occurs? (Refer to plate tectonics.)

In a normal fault, the hanging wall has moved down relative to footwall. Minimum compression stress is horizontal; maximum compression stress is vertical. Happens in an extension stress setting. Divergent plate boundaries. Brittle deformation.

Imagine a reverse fault. What direction does the hanging wall move? In which stress setting does this occur? At which plate boundary does the occurs? (Refer to plate tectonics.)

In a reverse fault, the hanging wall moves down relative to footwall. Maximum stress is horizontal; maximum stress is vertical. Convergent plate boundaries. Brittle deformation.

Imagine a strike-slip fault. What direction do the fault walls move? In which stress setting does this occur? At which plate boundary does the occurs? (Refer to plate tectonics.)

Horizontal to the surface. Rock masses slip past each other horizontally (as compared to normal and reverse which are vertical). Transform plate boundary. Brittle deformation.

In which stress setting does shear strain form? At which plate boundary? Brittle or ductile strain?

Force is parallel to surface, transform plate boundary, ductile strain, shear stress.

In which stress setting does stretching form? At which plate boundary? Brittle or ductile strain?

Divergent boundary, tensional stress (pull apart), ductile strain.

In which stress does folding form? At which plate boundary? Brittle or ductile strain? Imagine the axis and axial plane of a folded layered rock - know where the limbs of the fold are.

Compression (squeeze together), convergent plate boundary, ductile strain.

Picture an anticline and syncline and their axises.

The Appalachian Valley and Ridge (ex: Blacksburg) is made of folded and faulted sedimentary rocks.

• Are the ridges anticlines and the valleys synclines?

• What made the ridges and valleys?

The ridges are anticlines (sandstone). The valleys are synclines (limestone, shale).

Strain at the microscopic scale can produce what important features in metamorphic rock?

Foliation and lineation caused by ductal flow. Shearin during metamorphism.

Simple plate tectonics:

plates are rigid with sharp boundaries.

Real plate tectonics:

zone of deformation exists near plate boundaries.

Seafloor spreading centers and continental rifts:

• Seafloor examples: Mid-Atlantic Ridge, East Pacific Rise

• Continental examples: Kenya Rift, Rio Grande Rift

• uplifted by mantle convection

• horizontal extension → extensional joints and normal faults

• magma from mantle creates new crust

Subduction and collision zones:

• Ocean-ocean examples: Japan, Indonesia, Aleutians

• Ocean-continent examples: Andes, Alaska, Washington, Oregon

• Continent-continent example: Himalaya

• horizontal compression → folds and reverse faults

• magma from mantle above subduction creates new crust

• regional and contact metamorphism

Transform faults:

• Example: Oceanic ridge transforms → examples: San Andreas Fault, Dead Sea Fault

• horizontal shear → strike-slip faults

• often a little extension or compression as well

What happens before, during, and after an earthquake? (stick-slip behavior)

Friction will initially be greater than the shear stresses. As elastic bending builds up, elastic strain accumulates while shear stress builds up and becomes greater than the friction.

How is energy built up and stored in the local rock?

Picture a rubber band or bent pencil. Energy stored in rock forms seismic waves when released.

What is at the earthquake hypocenter?

Where the slip starts (below ground).

What is at the earthquake epicenter?

The place on a map where the hypocenter is located.

What is an earthquake?

A brittle strain event - rapid slip on a fault. It releases elastic potential energy - elastic rebound.

What is elastic rebound?

Elastic energy released during an earthquake.

Where does the energy go from an earthquake?

Rocks move, grind, break, heat up (friction), and vibration is created (seismic waves -- similar to sound).

What are seismic waves? What travels with the wave?

(Waves are traveling oscillations, but what oscillates?) The shaking from the earthquake. Body waves (inner layers of Earth) and surface waves (only along surface) are both types of seismic waves. Mass oscillates around the hypocenter.

What is a p-wave? What type of strain is it? What is the direction of particle motion? What is the speed? How strong is the shaking? How hazardous is it? How does it behave in fluids? (What is the other name?)

Compressional wave. Elastic normal strain. Thousands of meters per second (6,000 in granite, 1,500 in water, less than 1,000 in soft soil, 330 in air). Primary/fastest wave. Fastest in fluids (liquids and gases). Shakes buildings. Not very dangerous.

What is an s-wave? What types of strain is it? What is the direction of particle motion? What is the speed? How strong is the shaking? How hazardous is it? How does it behave in fluids? Why does it behave that way?

Stonger shaking than p-wave. Elastic shear strain. Shear wave. Up and down. 3,600 m/s in granite and less than 500 m/s in soft soil. Does not exist in water/air. Causes buildings to vibrate side to side. Most dangerous because horizontal movement is more hazardous to buildings than vertical movement.

What is a surface wave? What type of strain is it? What is the direction of particle motion? What is the speed? How strong is the shaking? How hazardous is it?

Interaction of compression and shear stress at Earth’s surface. Two kinds of surface waves: Love (side to side) and Rayleigh (up and down). Slowest waves. Strongest shaking which causes the most damage.

Compare p-waves, s-waves, and surface waves. Which type of wave arrives first, second, and third? Which wave causes the most damage from an earthquake?

P, S, then surface. Surface causes the most damage; p cause the least.

What is a seismometer?

A machine that records when shaking occurs.

What is a seismogram?

A plot that depicts the data recorded by a seismometer; records how far the ground moved.

Explain triangulation to find the earthquake hypocenter.

Using multiple seismometers to find the point where an earthquake occurs.

What is the amplitude of ground shaking?

Maximum different in ground shaking (+-0.5 inches).

Earthquake magnitude: M=log10A+C (10 is subscript) What are M and A? Understand implications of log-base-10. A magnitude N (such as 5) earthquake is how much stronger than a magnitude N-1 (such a 4) event? How much stronger amplitude of ground shaking is there? Since energy is proportional to A²/3, how much stronger is the energy of ground shaking?

M is earthquake magnitude and A is amplitude of ground shaking. Amplitude is 10x stronger.

How large does an earthquake need to be to damage buildings?

5.5

How many earthquakes M>6 are there annually? What is the relationship between magnitude and number of global earthquakes per year?

Inverse relationship - the higher the magnitude the less often they occur. Millions of 2, hundreds of thousands of 3, tens of thousands of 4, thousands of 5, hundreds of 6, tens of 7, around one 8 and 9.

In terms of global energy release, which is more important: the very small number of large earthquakes, or the very large number of small earthquakes? Which has more energy? What about in terms of global earthquake damage?

Magnitude 9 has the total amount of energy of all small magnitude earthquakes. The higher magnitude causes the most damage and deaths.

Where on Earth do the most earthquakes occur? Where are the most powerful and most damaging ones?

The Pacific Ring of Fire has the most earthquakes. The most powerful and damaging are in subduction zones.

Why do many large earthquakes cause no damage or deaths?

The ones where people don’t live there.

Why are there few earthquakes deep in the Earth?

(hint: where do brittle and ductile deformation take place?)

There is so much compression and heat. (hint: continental crust)

What type of plate boundary is the San Andreas Fault in California? Which plates? What type of fault (normal/reverse/strike-slip)?

Transform plate boundary. Pacific Plate slides past North American plate. Strike-slip transform fault.

Describe the factors that affect the amount of ground shaking in an earthquake. For each, explain why. (There are five.) Based on this, give at least two places where buildings should not be built.

Factors:

1. magnitude of earthquake (more energy, more shaking)

2. direction effects of earthquake slip

3. distance from hypocenter (as energy spreads, the strength per unit area decreases)

4. wave attenuation due to regional geology (east=elastic ; west=not elastic (not as far of shaking)

5. site conditions (sediment amplifies shaking; bedrock does not; wet mud/landfills amplify shaking A LOT)

Should not build on:

1. landfills

2. muddy/wet areas

Should anchor large buildings to bedrock. Ground shaking doesn’t kill people, collapsed (engineered) structures kill people. If you sit in the middle of an empty field during an earthquake, you’re good.

Why was shaking felt much further away from the 2011 VA earthquake than for western US earthquakes?

east=elastic ; west=less elastic

more solid rocks in the west - think of CA vs VA

Where was the worst damage and deaths in the 1989 Loma Prieta (near San Francisco) earthquake? Why did it occur there? (Why not near the epicenter?)

On San Jose fault (wet bay mud, sediment, and rock areas). The worst damage was on wet bay mud areas because shaking was amplified by bay mud and landfill.

Would you rather be in a small family home or a concrete and cinder block building during an earthquake? Why?

Family home because wood is flexible; concrete is not flexible. Extra info: wood and steal are flexible; concrete and bricks are not. The best buildings to be in are wood frame, then steel frame with reinforced concrete, and then (the worst) is brick/block/unreinforced concrete. Building codes protect and prioritize high risk structures; disaster response plans are needed.

If you were caught in a M=7 earthquake, would you rather be in a modern Virginia building or a modern California building? (Think about building codes.)

Likely CA because they experience more earthquakes and are better prepared/have stricter codes.

Explain methods, that are not ground shaking, than an earthquake can cause damage. (There are five.) For each, explain where not to build.

1. Ground rupture: when the fault splits and slides the ground in half - “ground swallowing”

2. Creep: continuous ground rupture (no large earthquakes) - slips and sliding

3. Landslide: unstable slopes can be triggered by an earthquake

4. Liquefaction: muds and wet soils can become liquid when shaken

5. Tsunami: water wave created by vertical motion of fault slip

(other info: 1. engineering: land use codes; disaster response plan 2. shoreline is bad to build on; high ground is good to build on)

What information is successfully used to predict earthquakes over a short (days) time period in order to evacuate/prepare?

***No patterns have been statistically proven or disproven

Prediction:

• specific damaging earthquake

• location (within 100 km)

• time period of days

Value:

• evacuation

• disaster response preparation

Possible Precursors (pre-earthquake phenomena)

• Foreshocks

• Ground deformation

• Ground water level and chemistry

• Electromagnetic (piezoelectric) signals

What is the basis of forecasts of the probability of an earthquake over a long (decades) time period? Why is it easier to make such forecasts in California than in Virginia? (The answer is related to, but different from the fact that Virginia is less likely to have earthquakes. Why is VA harder to quantify?) What is the value of such forecasts?

Forecasting:

• probability of exceeding a certain magnitude or ground shaking

• location (within 100 km)

• time period of DECADES

Value:

• building codes

• land use codes

• disaster response plans

Based on known earthquake patterns:

• earthquake history

• measured stress build-up

• plate boundaries have lots of data

• plate interiors have limited data

• earthquakes are rare, history is short

What does a seismic hazard map show?

Shows the history of earthquakes and the most likely spots for earthquakes.

What is induced seismicity? What causes it? Explain why.

Wastewater injection causes it. It’s when wastewater is pumped deep underground, so it doesn’t have to be sanitized. It increases water pressure, reduces effective normal stress and friction (lubrication of rocks), and can trigger earthquakes in pre-stressed rocks. First documented in the 1960s. Recent methods for enhanced recovery of oil and gas are also causing this (fracking included).

How many earthquakes occurred in the USA in the past week? How big were they (smallest magnitude)? Were they at/near plate boundaries? Explain Oklahoma-Texas.

54 earthquakes; smallest = 0.7 largest=4.2; mostly at plate boundaries except some in central U.S.

How many earthquakes occurred in the world in the past month? How big were they (smallest magnitude)? Were they at/near plate boundaries? Any exceptions?

1663 earthquakes; most at or near plate boundaries, some right in the middle of plate boundaries; smallest=in the 0.x largest=6.7.

How many earthquakes occurred in California in the past week? How big were they (smallest magnitude listed)? Were they at/near plate boundaries?

Around 70-80; in the 2s (smallest), biggest=4.8; yes, at or near plate boundaries.

How many earthquakes occurred near Virginia in the past year? How big were they (smallest magnitude)? Were they at/near plate boundaries?

Few, not many earthquakes - in the tens. Not near plate boundaries. In the 2s for magnitude.

What should you do now/during/after an earthquake?

Now: make an emergency plan and protect your home (secure heavy items in place).

During: if in a car, pull over; if in bed, turn face down and cover neck and head; if outdoors, stay away from buildings; if inside, stay and don’t run outside and avoid doorways.

After: expect aftershocks; get out of/do not enter damaged buildings; if you are trapped, call for help; if your area is at risk for tsunamis, go inland or to higher ground right after shaking stops; make sure you and others aren’t hurt.

What is the common (but geologically technically incorrect) word for mass movement (also called mass wasting)?

Landslide (it’s technically a narrower definition, but we use it in the English language anyway.) Earth materials falling downhill because of gravity.

Picture the forces that act on a mass on a slope. Describe how each force affects sliding.

Force of gravity, normal force, shear force, and friction force (coefficient of friction = property of boundary). A slip occurs when shear force>friction force. Stability depends on: angle, shear force, shear strength, and stress vibration.

If the stress (force) is due only to gravity and the slope of a surface gets steeper:

• does the shear stress on the surface increase or decrease?

• does the normal stress increase or decrease?

• does the friction increase or decrease?

• is the movement on the surface more or less likely?

• increases

• decreases

• decreases

• more likely

the steeper the slope the more likely it is to be unstable

Describe whether each of the following increases or decreases the chance of a slope moving and how:

• tectonics

• erosion undercutting (and how to reduce)

• mass added to the top of the slope (give examples)

• weak materials (name the most important weak mineral)

• pre-existing weak planes (give some examples)

• weathering

• tectonics: steepen → less stable (build mountains by tectonic plates)

• erosion undercutting: erosion at base → undercutting = remove of lateral support; reduce (make more stable) by building structures or having more vegetation (specifically trees with large roots

• mass added to the top of slope makes it less stable (house, big tree, watering)

• weak materials: shear strength: weak mineral → less stable; pre-existing planes of weakness in rock, weak sediment or soil, most common weak mineral is clay

• pre-existing weak planes: fractures etc

• weathering: weakens the material and makes it less stable; mechanical weathering, freeze-thaw plant roots, animal burrows, chemically weathering to weaker minerals (clay), water: lubrication

What is a pore in sediment or rock?

Space between mineral grains filled with fluid (example: air, water, oil, etc. - think back to rock with plastic)

What is the angle of repose? Picture it for dry gravel, dry sand, and dry clay. What is the rule for dry sediment? Picture it for damp sand (water and air in pores) - why? Picture it for wet sand (water in pores) - why?

Mini landslides happen and pile stays at the same height. Smaller clasts have smaller angles of repose and larger clasts have bigger angles of repose. Gravel can have steep piles, sand less steep, and clay is even less steep. Rule: water and air in pores makes it stick together and angle of repose is bigger. When there is only water in pores, the angle of repose is very flat.

What does water pressure do to the normal stress? What does it do to the friction? Is the soil/rock strengthened or weakened? What is liquefaction; what happens?

Water pressure reduces effective normal stress=reduced friction and shear strength (think of slippery when wet signs). With liquefaction, effective normal stress = 0, shear strength = 0, and flows like a liquid (picture of whole building sunk into the ground).

What common mineral group expands when wet and contracts when dry, and thus contributes to downslope movement? How does the slope move? What type of mass movement? Example of effects?

Clay expends when wet and shrinks why dry. Water expands when frozen and shrinks when it thaws. When these two things expand, the slope moves outward perpendicular to the slope. When they shrink, it does not go back the same way, it moves downward. The slope is moving downhill. Examples: creep, fence posts uneven, and pistol butt of a tree.

What other common process can cause expansion-contraction cycles and downslope movement? Describe each type of technical names for types of mass movement.

• Fall (How fast?):

• Slide (How fast? What is a scarp?):

• Slump (How fast?):

• Flow (How fast? Role of water?)

• Creep (How fast? Role of expansion/contraction cycles?):

• Avalanche (How fast?):

• Turbidity Current (What hazard?):

• fall (or roll): 10s of km/h (super fast, fall and roll is how we make the angle of repose)

• slide: technically a special piece of physics of how material moves downhill. The material moves downhill by sliding/slipping like a block on a flat surface. This happens at bicycle speeds, pretty fast, but not as much as fall/roll. After material moves we have a steep surface left behind - called a scarp.

• Slump: like slide but chunk rotates on the curved surface, rolling downhill (inside materially is still generally intact). Can be slower than slide but doesn’t have to be. Also has a scarp.

• Flow: flow like fluid- liquefaction. It internally deforms. As fast as miles or kms per hour. Role of water is lahar mud flow and liquefaction.

• Creep: slow flow (like a rock or glacier). Only millimeters to meters per year.

• Avalanche: fast flow suspended in air. Can occur with dry, small particle soil/sediment. Very fast, 10s of km/hr.

• Turbidity current: flow suspended in water (on continental slope, tsunami hazard), kms per hour, tsunami hazard (it can behave as if the whole seafloor moved).

Explain how mass movements can create the following:

• a lake

• a flash flood

• slide → block river = natural dam → lake

• natural dam breaks → flash flood

Name at least four things that humans should, or should not, do to reduce the risk of mass movement. (Advice based on previous info.)

Don’t:

• undercut slope

• steepen for landscaping

• add mass to top of hill

• add water

• increase wet dry cycles

• remove vegetation (increase erosion)

How do geologists and geotechnical engineers study to risk of slope failure?

They ask:

• What are the materials? Rock, sediment, soil? What type?

• Are there planes of weakness already?

• How does the water flow? How will it after a hurricane or a rainy season? Does it change with time?

• Is there evidence of past movements?

What are the warning signs of landslide hazards?

• springs, seeps, or saturated ground in areas that’s not typically like that

• new cracks or unusual bulges

• soil moving away from foundations

• structures (decks and patios) tilting and/or moving relative to main house

• broken water lines and other underground utilities

• messed up roads

• rapid increase in creek water levels and possible increased turbidity

• sticking doors and windows (out of plumb)

• faint rumbling sounds and other unusual sounds (trees cracking or boulders knocking together)

What should you do before/during/after a landslide?

Before:

• don’t go near slopes or mountain edges, drainage ways or natural erosion valleys

• get a ground assessment of your property

• know the landslide history of your area

• watch storm and water drainage patterns

• know emergency-response and evacuation plan for area

• minimize home hazards (pipe fittings, ground cover on slopes, retaining walls, channels or deflection walls)

During:

• stay alert

• leave the area if possible

• listen for unusual sounds

• watch water levels

After:

• stay away from slide area

• check local alerts

• watch for floods

• make sure everyone is okay

• check foundation and utility lines