A landslide or landslip is a geological phenomenon which includes a wide range of ground movements, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. Although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability.
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Step 1: Causes
• groundwater (pore water) pressure acting to destabilize the slope
• erosion of the toe of a slope by rivers or ocean waves
• earthquakes adding loads to barely stable slope
• volcanic eruptions
Step 2: Landslides Are Aggravated by Human Activities, Such As:
• vibrations from machinery or traffic
• earthwork which alters the shape of a slope, or which imposes new loads on an existing slope
• Construction, agricultural or forestry activities (logging) which change the amount of water which infiltrates the soil.
Step 3: Before a Landslide
• The following are things you can do to protect yourself, your family and your property from the effects of a landslide or debris flow:
• To begin preparing, you should build an emergency kit and make a family communications plan.
• Become familiar with the land around you. Learn whether debris flows have occurred in your area by contacting local officials. Slopes where debris flows have occurred in the past are likely to experience them in the future.
• Get a ground assessment of your property.
Step 4: During a Landslide
• Listen to local news stations on a battery-powered radio for warnings of heavy rainfall.
• Listen for unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together.
• Move away from the path of a landslide or debris flow as quickly as possible. The danger from a mudflow increases near stream channels and with prolonged heavy rains. Mudflows can move faster than you can walk or run. Look upstream before crossing a bridge and do not cross the bridge if a mudflow is approaching.
• Avoid river valleys and low-lying areas.
• If you are near a stream or channel, be alert for any sudden increase or decrease in water flow and notice whether the water changes from clear to muddy. Such changes may mean there is debris flow activity upstream so be prepared to move quickly.
• Curl into a tight ball and protect your head if escape is not possible.
Step 5: After a Landslide
• Stay away from the slide area. There may be danger of additional slides.
• Listen to local radio or television stations for the latest emergency information.
• Watch for flooding, which may occur after a landslide or debris flow. Floods sometimes follow landslides and debris flows because they may both be started by the same event.
• Check for injured and trapped persons near the slide, without entering the direct slide area. Direct rescuers to their locations.
• Look for and report broken utility lines and damaged roadways and railways to appropriate authorities. Reporting potential hazards will get the utilities turned off as quickly as possible, preventing further hazard and injury.