Have you ever seen a depression in the yard or near the house? It can be a sign of sinkhole formation. Are you wondering, “What is a sinkhole?” This is the depression in the natural ground surface caused by the collapse of the overlying earth. This can pose serious risks to infrastructure and human safety.
Read this blog to avoid this sinkhole formation, understand the causes, and take preventive measures before it’s too late.
What is a Sinkhole?
You can understand a sinkhole as a depression or hole in the ground that is generated when the surface layer collapses into an underground void. These features are most commonly found in areas with soluble bedrock, like limestone, gypsum, or salt, where natural processes slowly dissolve the rock, creating cavities beneath the surface. Sinkholes can vary in size from a few feet to several hundred meters in diameter and depth. They may develop gradually over time or appear suddenly, often causing significant damage to property and infrastructure. Sinkholes are also known as dolines, shakeholes, or swallow holes in different regions.
What are the Causes of Sinkholes in Residential Areas?
When you think deeply, “What causes sinkholes?” It can be caused by natural processes and human activities, often weakening the ground.
Natural Causes of Sinkholes
Karst Process
One of the natural causes of sinkholes is the Karst process. As you all know, stones and earth are also made of limestone, gypsum, or other soluble salt rocks. The salt content in the bedrock will dissolve or chemically react with water and gradually create underground voids. When these cavities grow large enough, the land above may collapse, forming a sinkhole.
Underground Water Flow
When water flows underground for a long time, it can slowly wash away soil and rock. This creates empty spaces or holes under the ground. If there is heavy rain or flooding, the water flow becomes stronger and can make these holes bigger, especially in areas with soft, easily dissolved rock (called karst regions). This can lead to the ground suddenly collapsing and forming a sinkhole.
Human-Induced Causes of Sinkholes
- Poor Drainage Systems: When drainage systems are blocked or don’t work properly, water can collect and slowly soak into the ground. This can dissolve certain types of rock (called soluble rocks) and make the soil weaker, which increases the chance of a sinkhole forming.
- Leaking Pipes or Sewer Systems: Old or damaged underground pipes can leak water. This water washes away soil and rock under roads or buildings, creating empty spaces. In city areas, this often speeds up sinkhole formation.
- Heavy Construction, Drilling, or Mining Activities: Large-scale construction, drilling, and mining disturb the ground and can remove support from underground cavities. The added surface weight from buildings or roads may also trigger collapses, especially in areas with a history of mining or weak subsurface geology.
- Over-Pumping Groundwater: When too much groundwater is taken out, the underground water level (called the water table) drops. This takes away natural support for underground spaces, which can cause the land above to fall in and form a sinkhole. This often happens in farming areas or places that use a lot of water.
What are Warning Signs of Sinkhole Formation?
Prevention is better than cure; thus, look for these signs of sinkhole formation to reduce the impact or avoid causing a disaster:
Structural Signs of Sinkhole Formation:
- Cracks in walls, floors, or foundations are among the most common early warning signs. These cracks may appear suddenly or widen over time, sometimes accompanied by the separation of walls from floors or ceilings.
- Doors and windows that no longer close properly or become misaligned can signal shifting or settling of the structure, often due to soil movement beneath the foundation.
- Sloping floors or parts of the building that seem to drop down may mean the ground below is becoming unstable.
Exterior Signs of Sinkhole Formation:
- Sudden ground depressions, localized sinking areas, or round, circular depressions in the yard often precede sinkhole formation. These can expose previously buried foundations, fence posts, or tree roots.
- Wilting vegetation in small, circular patches may indicate that water is draining into an underground void, depriving plants of moisture.
- New or unusual ponding or pooling of water in areas where it did not occur before can signal changes in ground drainage, often due to developing subsurface cavities.
- Slumping or tilting of trees, fence posts, or outdoor structures is another exterior clue.
Utility Issues:
- Sudden water discolouration or a noticeable drop in water pressure may suggest leaking or damaged underground pipes, which can erode supporting soil and contribute to sinkhole development.
- Cloudy water from wells or utility disruptions are also potential signs that the ground is shifting or that voids are forming below the surface.
How to Prevent Sinkholes With Measures Before & During Construction in India?
As sinkhole formation is a natural phenomenon you can take preventative measures to mitigate the risk of sinkholes. You cannot solve this issue permanently.
Site Evaluation Before Construction
You can take the following measures before starting the construction:
Geotechnical Survey:
You need to hire a geotechnical team to perform detailed site investigations to study the site’s subsurface conditions. Here, you can understand the site’s soil composition, groundwater levels, and the presence of karst characteristics that can become a cause of sinkhole formation in the future.
Geological Mapping:
You can review local geological maps to identify areas with karst terrain or sinkhole-prone zones. This step helps avoid building in places that are at high risk unless necessary precautions are taken.
Ground-Penetrating Radar (GPR):
Utilizing GPR and other advanced technologies, such as electrical resistivity tomography, allows for the detection of underground cavities or limestone bedrock that may be susceptible to dissolution and collapse.
Sinkhole Mitigation Techniques During Construction
Proper Foundation Design:
Often avoid constructing your residential building near karst areas in India.
For advanced safety, you start building your home with deep foundations such as pile foundations or piers foundations, which can transfer building loads to more stable strata.
During the construction, you can add more reinforcement to the foundation with steel beams or use grouting techniques to stabilise foundations and reduce the risk of settlement or collapse.
Drainage Control:
Installing French drains, ensuring proper site grading, and implementing gutter systems divert surface water away from foundations, reducing the risk of soil erosion and water infiltration into underground voids.
Avoiding excessive irrigation near the building foundation helps maintain soil stability and prevents the creation of saturated zones that could trigger sinkhole formation.
Soil Stabilisation:
You can stabilise the soil by using compaction grouting, where grout is pumped into the ground to fill empty spaces and strengthen weak soil. Avoid excavating too much during construction. This can disturb the underground layers and weaken the ground, leading to problems like sinkholes.
How to Mitigate Sinkhole Risks in Existing Homes?
Regular Infrastructure Inspections and Maintenance
Frequent inspection and maintenance of underground utilities—especially ageing water and sewage lines—are essential for the early detection of leaks and weaknesses that can trigger sinkholes. Indian cities are increasingly adopting technologies like ground-penetrating radar (GPR) and acoustic leak detection for mapping and monitoring underground infrastructure, particularly in metro areas. However, regular visual checks and immediate repair of visible leaks or ground subsidence remain crucial for most residential areas, especially where advanced technology is less accessible.
Fix Water Leaks Immediately
If you see any broken pipes, leaking sewer lines, or drainage problems, fix them right away. Leaking water can slowly wash away the soil beneath your home. This weakens the ground and can lead to a sinkhole. Regular maintenance of your plumbing and drainage systems helps keep the soil stable and your home safe in the long run.
Landscaping Adjustments:
Be careful when choosing plants around your house. Avoid planting trees with large or deep roots near the foundation, as their roots can disturb the soil and make underground spaces worse. To control soil erosion and guide rainwater properly, use retaining walls—especially if your house is on a slope.
Professional Help:
If you notice the ground sinking or cracks in your walls, it’s best to call a structural engineer or a geotechnical expert. They can check the problem and suggest solutions. Methods like underpinning (strengthening the foundation from below) or slab jacking (lifting and leveling sunken concrete slabs) can help make the foundation strong again and keep the house safe.
Does Home Insurance Cover Sinkhole Damage in India?
Typically, standard homeowners insurance policies do not cover damage caused by sinkholes. These sinkholes are generally considered “earth movement” events, which are often excluded from standard policies. Not only are earth movements hard to predict, but they are also difficult to investigate. Thus, you can’t expect to receive home insurance offering benefits on sinkholes.
Government Regulations & Building Codes to Minimize Sinkhole Risks in India
In India, the National Building Code (NBC) and local development authorities already set guidelines to improve structural safety and reduce sinkhole risks. According to NBC, conducting a thorough geotechnical investigation and soil testing is compulsory before construction, especially in areas prone to subsurface instability. Structural design must comply with code provisions to ensure stability against natural hazards, including ground subsidence and sinkholes.
Before starting the construction, your building plans should get approval from the respective authorities, and safety certifications by structural engineers are mandatory for high-rise and special buildings. Regular inspections and maintenance of underground utilities, as recommended by the NBC, further help prevent soil erosion and sinkhole formation.Sinkholes can cause serious damage if not detected and managed in time. From natural factors like underground water flow to human activities such as poor drainage and over-extraction of groundwater, several causes can weaken the ground beneath your home. Early warning signs—such as ground cracks, misaligned doors, or unusual water pooling—should never be ignored. Regular maintenance, proper site evaluation, and expert guidance can help you to prevent disasters. If you’re planning to build a new home, don’t take chances. Reach out to Brick & Bolt, a trusted construction partner, for expert support in planning and building a sinkhole-resistant home.