Subsidence/Sinkholes – Mitigation (Actions Before, During, After)


A sinkhole, also known as a sink, sink-hole, shakehole, swallet, swallow hole, or doline (the different terms for sinkholes are often used interchangeably), is a depression or hole in the ground caused by some form of collapse of the surface layer.

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Subsidence/Sinkholes – Mitigation

The following actions are some important recommendations that you can follow through each stage of a Subsidence or Sinkhole emergency:[1] [2]


Actions Before: Increase Knowledge, Determine Risk, Safeguard, Plan

Signs that indicate sinkhole formation, especially in regions (such as Florida) where they are most likely to occur, should be interpreted by inspectors as a serious safety hazard.

General All-Hazard Actions:

  • Determine the disaster risks in your locale and the hazards that accompany them.
  • Increase your knowledge about the emergency warning signals and alert notifications used in your community.
  • Instruct family members how to shut off water, gas and electricity to your house.
  • Make the necessary property preparations to reduce the damage from the hazard.
  • Acquire a backup generator in case of a prolonged power failure.
  • Check into insurance (property, health, life, and hazard type).
  • Make the necessary financial arrangements in case of a sudden evacuation and power outage that shuts down local ATMs and banks.
  • Organize important documents and records and store them in a portable lock box or safe-deposit box.
  • Perform home inventory video taping and store tape in a portable lock box or safe-deposit box.
  • Develop an Emergency Communication Plan with evacuation plan and ask an out-of-state person to serve as the "family contact".
  • Assemble a shelter-in-place Emergency Supplies Kit.
  • Assemble a mobile Emergency Supplies Kit that can serve as a “grab and go” bag?
  • Get a family member trained in first aid and CPR.
  • Make the necessary preparations and arrangements for pets, seniors, and the disabled.
  • Familiarize yourself with the emergency plans of your family member's employment building, school, day care center, or nursing home.

Hazard Specific Actions:

In homes and buildings, look for:

  • Cracks in your exterior of your home, such as in the block or stucco;
  • Cracks in interior areas along joints, windows, or doors;
  • Doors and windows that don't close properly;
  • Floors sloping and becoming uneven;
  • Muddy or cloudy well water.

On the property, check for:

  • Previously buried items, such as foundations, fence posts and trees becoming exposed as the ground sinks;
  • Gullies and areas of bare soil, which are formed as soil is carried towards the sinkhole;
  • A circular pattern of ground cracks around the sinking area. Sudden earth cracking should be interpreted as a very serious risk of sinkhole or earth collapse. The first sign that a sinkhole was developing in Daisetta, Texas was the opening up of cracks in the ground and in the roadway on the morning of its collapse;
  • Localized, gradual ground settlement;
  • Formation of small ponds, as rainfall accumulates in new areas;
  • Interrupted plumbing or electrical service to a building or neighborhood due to damaged utility lines;
  • Vegetation that wilts and dies as essential water is drawn away by the sinkhole;
  • Slumping or falling trees or fence posts;
  • Sudden ground openings; and
  • Sudden ground settlement.

Actions During: Safety Basics, Evacuation, Shelter in Place

Here are some basic guidelines to follow if you have a sinkhole on or near your property:

  • Mark the hole for safety but restrict access.
    • Use posts or sawhorses with caution tape or rope.
    • Place a piece of plywood over a small hole.
    • Notify all parties: occupants, owners, real estate agents and buyers.
    • Notify the local Water Management District.
    • Keep children away!
    • Take photographs for documentation, but do not get too close to the edges.
    • Contact the homeowner's insurance company.
  • If the hole is very large, contact local police or emergency responders, especially if the hole is a hazard to the public, affects an occupied dwelling, near a utility line, in a roadway, or on a sidewalk or trail.
    • You may want to notify your municipality as well who may (or may not) be able to assist you with repairs.
  • Do not get too close.
    • If the hole is on your property, take photos for documentation but be cautious!
    • The edges of the hole may be unsupported and further collapse and growth of a hole is common.
    • Watch for surface cracks and stay back.
  • Do not allow unauthorized or inexperienced persons to investigate the sinkhole.
    • In no instance should you or anyone else crawl down or be lowered into a hole with no visible bottom. The soil around a void will eventually collapse.

Actions After: Get Disaster Relief, Clean-up, Salvage

Do not fill a hole with trash or debris.

  • Use only clean soil or fill, without organic content.
  • If the hole is large, the volume of material needed to fill it may be too great or additional materials such as concrete and large rock may be required.
  • Contact an experienced individual to assist you.
  • Try to divert any extra water away from a hole before, during and after filling.
  • Use qualified, reliable individuals or companies for repair. Filling a sinkhole with waste materials is illegal and may cause groundwater contamination for which the property owner would be liable.



  1. Lake County,, American Red Cross, CDC – Emergency Preparedness and Response, FEMA – Are You Ready? Guide,, Be a Force of Nature with NOAA’s Weather Ready Nation, National Weather Service Weather Safety
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