Review - A flood occurs... Any time a body of water rises to cover what is usually dry land.

What are some causes of floods?

Causes of Floods  Heavy rain  Spring snowmelt  Dam and levee failure  Low absorption or no soil percolation

What are some contributing factors for flooding?

Factors Contributing to Flooding  Rainfall intensity  Rainfall duration  Topography  Soil conditions  Ground cover

Question?  What is the NUMBER ONE RULE where flooding is concerned?

Answer!!  Move to Higher Ground!  Carry debris, trigger landslides  Fast moving waters 24 in. deep can carry away a vehicle  6 in. swiftly moving water can knock someone off feet  Never try to walk, swim or drive through flood waters!

An ocean wave produced by earthquakes or underwater landslides. Review- A Tsunami Is...

Risks Posed by Tsunamis Tsunamis can cause:  Flooding.  Contamination of drinking water.  Fires from ruptured tanks or gas lines.  Loss of vital community infrastructure.

Tsunami Pose the greatest risk to areas less that 25 ft. above sea level Within 1 mile from shore

Destruction to everything in path

Tsunamis  Six Tsunamis have hit the U.S. since 1945  24 in the last 225 years

Tsunami Warning Tsunami Warnings originate from two agencies  The West Coast/Alaska Tsunami Warning Center (California, Oregon, British Columbia & Alaska)  The Pacific Tsunami Warning Center (Hawaii, U.S. Territories in the pacific basin)

If a Tsunami Warning Is Issued  If in a tsunami risk area, evacuate immediately.  Follow instructions issued by local authorities.  Get to higher ground as far inland as possible.  Listen to a NOAA Weather Radio or Coast Guard emergency frequency station.  Return home only after local officials tell that you it is safe.

Landslides - Review What is a landslide?

A Landslide Is... A rapid shift in land mass that is typically associated with periods of heavy rainfall or rapid snowmelt, and tends to worsen the effects of flooding that often accompanies these events.

What are some causes for landslides?

Landslides  Increased number of landslides annually are caused by:  Deforestation  Wildfires  Development

Debris Flow? Debris Flows - AKA Mudslides, Mudflows, Lahars and Debris Avalanches.  All are moving debris of some kind – generally pick up additional debris as they move: trees, rock, boulders, cars and sometimes homes  Water & land = Mudslide  Water, mud, lava = Lahars  Snow, land, trees = Debris Avalanche

Volcanoes

A Volcano Is... A vent through which molten rock escapes to the Earth’s surface.

Volcano Unlike mountains that are pushed up… Volcanoes are formed by surface accumulation of eruptive products  Layers of Lava  Ash Flows  Ash

Volcanoes Top Three Countries with active volcanoes Japan Indonesia United States

Volcanoes 5 U.S. eruptions Since 1980

Volcano Eruption Eruption – occurs when pressure from gases within molten rock have become to great  Eruptions can be relatively quiet with flows 2-10 mph  Explosive, shooting gas & rock 10’s of miles into air

Volcanoes Most Likely place for U.S. volcano eruption:  Hawaii & Alaska  Cascade Range  Washington  Oregon  California

Volcanic Hazards  Toxic gases  Lava and pyroclastic flows  Landslides  Earthquakes  Explosive eruptions

Volcanic Eruptions Lava - streams of molten rock  Pour from vent quietly  Erupt explosively as lava fountain

Lava  Intense Heat  Destroy everything in path  Move relatively slow

Lava Speed Factors that effect lava speed  Type of lava  Steepness of ground  Rate of lava production at vent

Pyroclastic Flows Fluidized masses of melted rock and gases

Pyroclastic Flow  Mixture of rock, molten rock, ash, lava and gases  Thicker at ground level lighter further away from ground.  Travels 20 – 40+ MPH, can travel for many miles  Wipes out everything in path

Accompanying Hazards  Mudflows (including lahars – mudflows at flanks of volcano made up of volcanic material, mud, rock & water)  Flash floods  Wild fires  Tsunamis  Earthquakes

Lahars Lahars historically have been the deadliest of hazards Made up of volcanic material, mud, rock & water Travel mph and go for 50 miles

Lahars Causes of Lahars – water built up in volcano by:  Melting snow  Heavy Rain  Breakout in summit crater lake

Question? What is Volcanic Ash?

Volcanic Ash  Fine glassy rock fragments and steam

Volcanic Ash Will  Cause severe respiratory problems.  Diminish visibility.  Contaminate water supplies.  Cause electrical storms.  Disrupt the operation of machinery.  Collapse roofs.

Question? How can you prepare for a volcanic eruption?

Volcanic Eruption Preparedness  Understand the risk.  Talk to your insurance agent.  Prepare a disaster supply kit.  Develop an evacuation plan.

Questions? What should you do during a volcanic eruption?

During a Volcanic Eruption  Follow evacuation orders.  Avoid areas downwind and river valleys downstream.  If outside, protect yourself from ash fall.  Be prepared for accompanying hazards.

Personal Safety  Wear long sleeve shirt  Use goggles  Wear glasses instead of contacts  Use dust mask or damp cloth

Question? What should you do after a volcanic eruption?

After a Volcanic Eruption  Stay away from volcanic ash fall areas.  Clear roofs of ash fall.  Avoid driving in heavy ash fall.  If you have a respiratory ailment, avoid contact with any amount of ash.

End of class Assignment  In groups of  Brainstorm – what steps can you take in and around your home to mitigate hazards from the following disasters?  Flood  Tsunami  Landslide  Volcano Five mitigation steps for each disaster.