Landslides & Mudflows

Transcription

1 1 2 - What is a Landslide? - Geologic hazard Common to almost all 50 states Annual global Billions in losses Thousands of deaths and injuries 3 1

2 - What is a Landslide? - Gravity is driving force Some move slowly and cause damage gradually Some destroy property and take lives suddenly and unexpectedly 4 - What is a Landslide? - Resistance keeps land (soil) in place Factors that allow the force of gravity to overcome the resistance include: Saturation by water Steepening of slopes (erosion, construction) Freezing and thawing Earthquakes Volcanic eruptions 5 - What is a Landslide? - Landslides associated with: Heavy rainfall Rapid snow melt Add to flood damage Burned land more likely to experience landslides 6 2

3 - What is a Mudflow? - Mudflows are rivers of rock earth and other debris saturated with water 7 - What is a Mudflow? - Develop when water rapidly accumulates in the ground Soil changes into a slurry 8 - Slurry Characteristics - Flows rapidly Strikes without warning Moves at avalanche speeds Travels miles Grows in size 9 3

4 - Insurance - Mudflows covered by National Flood Insurance Landslides not covered Landslide Risk - Historical occurrence Identifiable hazard locations Information Sources Local officials State geological surveys Departments of natural resources University departments of geology 12 4

5 - Landslide Risk - Landslide Risk in the Continental United States Mitigation - Become familiar with land Identify evidence of landslides or mudflows 15 5

6 - Check Warning Signs - Patterns of storm-water drainage Places where runoff water converges Signs of hillside movement 16 - Minimize Hazards - Plant ground cover Build retaining walls Build channels or deflection walls to direct the flows around buildings 17 Install flexible pipe - Minimize Hazards

7 - Other Steps - Check with your insurance agent Develop a Disaster Plan Responsibilities Evacuation route Emergency Action Plan Assemble a Disaster Supplies Kit 19 - Make a Landslide - A landslide s damaging effects dependent on different factors Some factors can be mitigated Some factors cannot be mitigated 20 << ATTENTION >> If presentation did not display in pop-up window, check pop-up blocker. Pop-up blockers need to be turned off. 21 7

8 22 - Response - Stay awake and alert Be aware of intense rainfall Tune to NOAA radio or TV 23 Consider evacuation Driving can be hazardous Move to upper floors Stay out of the path - Response

9 - Response - Listen for unusual sounds Trickle may precede larger landslides Exercise caution since debris can flow quickly and without warning 25 - Near Stream or River - Be alert to increase or decrease in flow Notice newly muddy water Prepare to move quickly Save yourself, not possessions 26 - Driving - Stay alert Remember road embankments are susceptible Note collapsed pavement, mud, fallen rocks 27 9

10 - Imminent Danger - Contact your local authority Inform affected neighbors Help neighbors who may need assistance to evacuate Stay out of path Recovery: First Steps - Stay away from the slide area Check for injured and trapped people Call for help Direct rescuers Help others 30 10

11 - Recovery: First Steps - Get latest emergency information Watch for flooding Identify and report damaged utility lines Inspect buildings Inspect surrounding land 31 - After the Landslide - Replant on damaged ground Minimize erosion Consult geotechnical expert

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