Geoscientist Chris Milliner of NASA's Jet Propulsion Laboratory (JPL) found that the Hurricane Harvey floods caused the city of Houston to sink down about two centimeters.
Flooding in downtown Houston [Photo by Reuters/C. Tycksen]
Hurricane Harvey was a Category 4 hurricane that turned out to be the first major hurricane to hit the US since 2005. Several areas in theGulf of Mexico experienced about 100 centimeters of rain, and there was intense flooding in Houston, Texas. 30,000 people had to evacuate from their homes, while thousands of homes were inundated by flood waters. These floods made over 17,000 rescues necessary.
However, this wasn't the entire extent of the effects of the floods. Milliner says that there was actually enough water in the Hurricane Harvey flooding to deform the Earth's crust. There was so much water that there was enough weight for the crust in some parts of southeastern Texas, including the city of Houston, to sink.
Of course, this raises many questions. For now, however, let's look at how this could have happened.
Map showing the sinking of the crust in Houston and the surrounding areas [Image by Chris Milliner]
The “how” of this is actually simple. More water on the surface means more weight. Let's look at the math: a gallon of water weighs about 8.34 pounds. According to some estimates, Hurricane Harvey dumped 33 million gallons of water on Texas, Kentucky, Louisiana, and Tennessee. Scientists calculate that about 275 trillion pounds of water was added to the weight on the crust in that area.
Milliner said on Twitter that it's like someone jumping on then off a mattress. He also included a map that showed data from the Nevada Geodetic Laboratory. According to the map, GPS data from around Houston showed that Hurricane Harvey floods pushed the entire area area down by two centimeters.
A mountain of water [Image via the Washington Post]
Two centimeters may not seem like much, but it's important to take note that it takes a lot to affect the Earth's crust in this way. That area of land carried an amount of water equivalent to 77% of the estimated mass of Mount Everest. it's safe to say, therefore, that a mountain of water fell on Texas and the other affected areas during Hurricane Harvey.
It's possible that the GPS readings were caused by the weight of the water compacting sandy soil, but Milliner says it's unlikely. Soil compaction could be a factor, but if the ground moves upward once the Hurricane Harvey floods recede, then we'll know for sure what the culprit was.
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