B A C K G R O U N D E R

LANDSLIDES AND WHAT IS A ? occur when masses MUDFLOWS of rock, earth, or move down a slope. Landslides may INFORMATION be very small or very large, and can move at slow to very 1. Acres of property may be damaged and buildings and homes high speeds. Many landslides destroyed by landslides. Landslides can provoke associated have been occurring over the dangers, such as broken electrical, water, gas, and sewage lines, same terrain since prehistoric and disrupted roadways and railways. times. They are activated by , , , and 2. Landslide warning signs include cracks opening on hillslopes; by human modification of the evidence of slow, downhill movement of rock and soil; tilting of land. New landslides occur as trees, poles, or walls; or visible changes such as the formation of a result of rainstorms, earth- sags and bumps in the slope. quakes, volcanic eruptions, and various human activities. 3. Landslide, mudflow, and debris-flow problems are often caused by land mismanagement. Improper land-use practices on ground of questionable stability, particularly in mountain, canyon, and coastal regions, can create many problems WHAT IS A MUDFLOW? associated with landslides, mudflows, and debris flows. Mudflows (or debris flows) are rapid movements of rock, DANGER ZONES earth, and other debris saturated with water. They develop when the ground becomes saturated such as during heavy rainfall or rapid snowmelt, or during a volca- nic eruption, changing the earth into a flowing river of or “slurry.” A slurry can flow rapidly down slopes or through channels, and can strike with little or no warning at speeds. A slurry can travel several miles from its source, growing in size as it picks up trees, cars and other materials along the way.

Landslides occur in every state of the Union and its island territories. California, West Virginia, Utah, Kentucky, Tennessee, , Ohio, and Washington have the most severe landslide problems.

The United States supports international efforts to raise awareness that natural risks can be managed: Federal Agency, American Red Cross, National Weather Service, U. S. Geological Survey, Department of Energy, Corporation for National Service, U. S. Army Corps of Engineers, Small Business Administration, National Aeronautics and Space Administration, Department of Transportation, Department of Education, and the National Interagency Center. HELP YOUR COMMUNITY GET READY HOW THE PUBLIC CAN The media can raise awareness about landslides and mudflows by HELP AFTER A providing important information to the community. Here are some suggestions: When disaster strikes, people everywhere want to help those 1. In an area prone to landslides, publish a in need. To ensure that this special section with emergency information compassion and generosity on landslides and mudflows. Localize the are put to good use, the media information by including the phone numbers can highlight these facts: of local emergency services offices, the American Red Cross, and hospitals. • Financial aid is an immediate need of disaster 2. Report on what city and county governments are victims. Financial doing to reduce the possibility of landslides. contributions should be made Interview local officials about local land-use through a recognized zoning regulations. voluntary organization to help ensure that contributions are 3. Interview local officials and major put to their intended use. insurers regarding the National • Before donating food or Insurance Program. Remind your clothing, wait for instructions community that mudflow is covered by from local officials. flood insurance policies from the National Immediately after a disaster, Flood Insurance Program. relief workers usually don’t have the time or facilities to 4. Work with local emergency services and American Red Cross set up distribution channels, officials to prepare special reports for people with mobility and too often these items go to impairments on what to do if evacuation is ordered. waste. • Volunteers should go through a recognized voluntary agency such as the DID YOU KNOW. . . American Red Cross or the Salvation Army. They know • The most expensive landslide • The Loma Prieta in what is needed and are in U.S. history occurred in October 1989 triggered prepared to deal with the need. Thistle, Utah, in spring 1983. thousands of landslides Local emergency services 1 officials also coordinate It reached 1 /2 miles from top throughout an area of 5,400 to bottom and ranged in width square miles. In addition to volunteer efforts for helping in from 1,000 feet to about 1 causing tens of millions of disaster. mile. Total costs attributable dollars of damage to houses, • Organizations and to the landslide exceeded $500 other structures, and utilities, community groups wishing to million. landslides blocked many donate items should first transportation routes, greatly contact local officials, the • Landsliding in the United hampering rescue and relief American Red Cross, or the States is estimated to cause an efforts. Salvation Army to find out annual loss of about $1.5 what is needed and where to billion and at least 25 • Mudflows tend to flow in send it. Be prepared to deliver fatalities. channels, but will often spread the items to one place, tell out over a floodplain. They officials when you’ll be there, generally occur in places and provide for transportation, where they have occurred a driver, and unloading. before.