Why Michigan has a bigger sinkhole problem than you might think

DETROIT – The ground under your home could collapse -- and you might not see it coming.

Few things are scarier than sinkholes.

Here’s what causes them, why Michigan is more vulnerable than you might think, and what to do if you spot one.

How sinkholes form

Sinkholes form when the ground beneath the surface can’t support what’s above it. The ground can look completely normal until the moment it gives way.

Sometimes the cause is something that can be controlled -- like a water main break washing away soil beneath a road.

But the more catastrophic sinkholes happen when water slowly dissolves rock underground, creating a hidden cavity. That rock can be salt, limestone or other carbonate rocks.

Why Michigan is at risk

Here’s the bad news for Michigan residents: The state has a lot of that vulnerable rock -- and a lot of groundwater to go with it. Nearly the entire Lower Peninsula sits on massive salt deposits.

Changes in groundwater or drainage can also raise the risk. That includes droughts, irrigation, storms, floods, deep freezes and construction activity.

Those are all things Michigan is very familiar with, unfortunately.

Wet and dry conditions can both play a role. Groundwater can actually support the weight above it in a way dry soil can’t -- but it can also carve out underground cavities that eventually trigger sinkholes.

How fast can sinkholes form?

Some sinkholes develop slowly, creating shallow dips in the ground before turning catastrophic. Others can form in a matter of hours and collapse without warning. That’s more likely when clay-heavy soil sits above underground cavities.

Here’s some good news: Michigan doesn’t have much clay, and the state isn’t even close to being the most vulnerable in the country for sinkholes.

Thanks for taking one for the team, Florida!

What to do if you spot one

If you notice new cracks, settling or sudden depressions in the ground, contact your city’s public works department, county road commission, the Michigan Department of Transportation or the Geological Survey. If it’s an emergency, call 911.