Landslide and debris flow safety tips

March 26, 2014
landslide-fema-la_conchita-ca

1995 landslide in La Conchita, CA Photo: FEMA

According to US Geological Survey, landslides in the United States cause approximately $1-$2 billion in damage and kill more than 25 people on average each year. Worldwide, landslides cause thousands of casualties and billions in monetary losses every year.

Researchers at UK’s Durham University recently reported that landslides kill ten times more people across the world than was previously thought. Their Durham Fatal Landslide Database (DFLD) showed that 32,300 people died in landslides between 2004 and 2010. Previous estimates ranged from 3,000 to 7,000 fatalities.

One of the worst landslides and subsequent loess [sediment] flows on record happened in 1920 when the 8.5 magnitude Haiyuan Earthquake shook China for 10 minutes killing over 100,000 people.

Although landslides and debris or mud flows are primarily associated with mountainous regions, they also occur in low elevations too. According to Science Daily some key landslide hotspots include China, the Philippines, Central and South America, and India, but slides can happen anywhere in North America too.

Landslides are basically masses of rock, earth or debris that move down a slope often triggered by many natural events such as earthquakes, floods or volcanic eruptions. The term “landslide” encompasses five modes of slope movement: falls, topples, slides, spreads, and flows and can be further subdivided by the type of geologic material (bedrock, debris, or earth).

Mudflows or debris flows (a type of landslide) are rivers of rock, earth, and other debris soaked with water mostly caused by melting snow or heavy rains creating a slurry. A slurry can travel several miles from its source and grows in size as it picks up trees, cars, and other things along the way. They can even move houses off their foundations or bury a place within minutes due to their incredibly strong currents.

Whidbey Island WA 2013 mudslide before after

Before and after photo of 2013 mudslide on Whidbey Island / Photo: Washington Department of Natural Resources

In addition to Mother Nature’s fury causing land movements, human activities like deforestation, cultivation, stresses on groundwaters, and construction on unstable land also play large roles.

There are some warning signs to indicate if you have a potential problem.

BEFORE A LANDSLIDE OR MUDFLOW:

Learn risks – Ask your local emergency management officeif your property is a “landslide-prone” area. Or call your County or State Geologist or Engineer or visit the USGS Landslide Hazards Program

Recent fires? – Be aware that areas hit by wildfires have an increased risk of landslides and mudflows once the rainy season starts.

Get insurance…? – Talk to your agent and find out more about the National Flood Insurance Program since mudflows are covered by NFIP’s flood policy.

Be prepared to evacuate – Listen to local authorities and leave if you are told to evacuate.

Where would we go? – Decide in advance where you would go in case you can’t return home for weeks or months .. or ever. If your home is damaged or destroyed or you’re forced to leave your home due to on-going threats (like mudslides or flooding), you’ll need to find temporary or permanent living quarters. This could mean staying in a public shelter or hotel, living with friends or relatives, or renting a home or apartment in the middle of all the chaos, so discuss several options now. Then, write down those options and share them with relatives and friends.

Reduce risks – Plant ground cover on slopes and build retaining walls.

Inspect – Look around home and property for landslide warning signs:

  • cracks or bumps appear on hill slopes, ground or roads
  • water or saturated ground in areas not normally wet
  • evidence of slow, downhill movement of rock and soil
  • tilted trees, poles, decks, patios, fences or walls
  • underground utility lines break
  • doors and windows stick or cracks appear on walls, etc.

Call an expert…? – Consult a professional for advice. Or visit the National Landslide Information Center

 

DURING A LANDSLIDE OR MUDFLOW:

Strange sounds – Listen for trees cracking, rocks banging together or water flowing rapidly (esp if near a stream or river) – debris flow may be close by.

Move it! – Whether you are in a vehicle, outside, or in your home – GET TO SAFER GROUND! Avoid low-lying areas, washes and river valleys and look upstream before crossing a bridge in case a debris flow is coming.

Listen – Tune in to local radio or TV reports to keep you posted on latest updates especially since other disasters like earthquakes, storms, flooding or volcanic eruptions may be associated with debris flows.

Be small – If there is no way to escape, curl into a tight ball and protect your head the best you can.

 

AFTER A LANDSLIDE OR MUDFLOW:

Listen – Local radio and TV reports will keep you posted on latest updates or check with your local police or fire departments.

Don’t go there – Stay away from the area until authorities say all is clear since there could be more slides or flows.

Things to watch for:

  • flooding – usually occur after landslides or debris flows
  • damaged areas – roadways and bridges may be buried, washed-out or weakened — and water, gas & sewer lines may be broken
  • downed power lines – report them to power company

Inspect – Look for damage around home and property and watch for new landslide warning signs:

  • check foundation, chimney, garage and other structures
  • report any broken utility lines or damaged roads to local authorities
  • watch for tilted trees, poles, decks, patios, fences or walls
  • notice doors or windows stick, cracks appear, etc.

Replant – Try to fix or replant damaged ground to reduce erosion, possible flash flooding or future landslides.

Call an expert…? – Consult a professional landscaping expert for opinions and advice on landslide problems. Also call an expert out if you discover structural damage to home, chimney or other buildings.

Insurance – If your home suffers any damage, contact your insurance agent and keep all receipts for clean-up and repairs.

Some additional things to check and do…

  • Check for gas leaks (smells like rotten eggs, hear a hissing or blowing sound or see discolored plants or grass)
  • Check electrical system (watch for sparks, broken wires or the smell of hot insulation)
  • Check appliances after turning off electricity at main fuse and, if wet, unplug and let them dry out. Call a professional to check them before using.
  • Check water and sewage system and, if pipes are damaged, turn off main water valve.
  • Consider having your house tested for mold.
  • Secure valuable items or move them to another location, if possible

Emotional recovery tips –   Disasters and emergencies may cause you to leave your home and your daily routine and deal with many different emotions, but realize that a lot of this is normal human behavior. Read more

Remember… the more you prepare before disaster strikes, the better off you and your loved ones will be financially, emotionally and physically.

 

Sources: It’s A Disaster! …and what are YOU gonna do about it? book and our “Slip Sliding Away” article in PREPARE magazine’s Sep 2013 issue

Our thoughts and prayers go out to all those impacted by the recent #530slide in Washington state. Stay current on news and learn how to help the victims at www.snohomishcountywa.gov/2354/530-Slide  j & B

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