How Does Liquefaction Affect a Home's Foundation After an Earthquake?

Soil liquefaction is a phenomenon where strong shaking from major ground movement causes water-saturated, loose soil, like sand or silt, to temporarily lose its solid strength. The ground essentially turns into a dense fluid that cannot support weight. This process is more common in areas with high groundwater tables and specific soil types. The sudden loss of bearing capacity is what makes it so dangerous for structures built on top.

After major ground movement, inspect your property for clear indicators of foundation problems. Look for new, significant cracks in your foundation, exterior walls, or interior drywall and flooring. Doors and windows that no longer open or close properly are a common sign. You might also see soil displacement, like sand boils or ejected sediment, in your yard near the foundation.

• Wide, uneven cracks in the concrete foundation slab or stem walls.
• Doors and windows that are jammed or have large gaps in their frames.
• Visible tilting of the house or unlevel floors you can feel when walking.
• Cracks radiating from the corners of doors and windows inside the home.
• Separation between the foundation and the exterior siding or brick veneer.
• Mud or sand venting through cracks in the ground around your property.

Your first priority is safety. If you see major structural damage, evacuate and contact local authorities. Once it is safe to re-enter, document all damage with photos and videos for your insurance company. Avoid using water or flushing toilets if you suspect broken pipes. You will need to consult a structural engineer to assess the foundation and a water damage pro for any resulting flooding.

• Ensure the structure is safe to enter; evacuate if there is major cracking or tilting.
• Shut off the main water valve to prevent flooding from broken pipes.
• Take extensive photographs and video of all damage, inside and out.
• Contact your insurance provider to start the claims process.
• Schedule an assessment with a qualified structural engineer.
• Call local water damage pros to address any interior flooding or moisture.