HOUSTON — Hurricane Harvey gave plenty of people in Houston a sinking feeling. Turns out, it wasn’t just emotional— it was also geological!
GPS data from the Nevada Geodetic Laboratory and the University of Nevada-Reno shows that the 1 trillion gallons of rainfall Harvey left over Houston in four days caused the area to sink by two centimeters.
“It’s a real phenomenon, and it’s something that’s related to the fact that the Earth’s crust and underlying mantle behaves kinda like a trampoline. Much more rigid than a trampoline, but it’s very much the same, so when you stand on a trampoline it goes down, when you step away it goes back up. This tremendous amount of rain we had is a sufficient enough load on the crust to have changed that in that way,” said Professor Peter Copeland from the University of Houston’s Department of Earth and Atmospheric Sciences.
That’s gotta be hell on the foundations beneath the buildings in Houston, right?
Well, not so much.
The effects Harvey had on the Earth’s crust was so wide in area, it alone won’t damage foundations, but the water soaking into the varying types of soil closer to surface level could have a huge impact for certain areas.
“Now, if you’re west of Houston, you’re in Pearland, you’re out there in Sienna Plantation, you’re out there in Telfair; those areas you got highly expansive soils and those areas can experience movement. Basically, those soils become saturated and they start changing volume, and they start lifting up the structures,” said David Eastwood, president of Geotech Engineering and Testing.
That doesn’t sound good. If you had feet of water in your home, and you haven’t made the transition from demolition to rebuilding yet, have your foundation inspected before your repairs.
“If you repair the inside of a home and then later you raise the foundation, it’s going to do damage to all of your repairs, cause anytime you move the slab it affects what’s above the slab,” explained Chris Cates with Olshan Foundation Repair.
What are some of the signs that show foundations of some houses were damaged? Cracks in brick, gaps between wood and brick, and as always, doors that stick.
The good news, as all the water still left in the soil dries out, the crust will return to normal. As for everything else that Harvey left behind, that will probably take a bit longer.