(Matthew Du, NewsUSA Reporter) - According to EcoHubMap, Houston is the 10th fastest sinking city worldwide, at a rate of 1.95 centimeters per year. However, other parts of the city sink for as much as two inches annually. 

What's causing this sinking woe?

Two main causes of sinking cities are ice caps melting and excessive groundwater drainage. 

Ice caps and glaciers melting are due to global warming or increased heat in the polar regions. Pollution, especially greenhouse gases, boosts this phenomenon. 

On the other hand, cities can pump out too much groundwater. Electric pumps are used to pump out water from underground for irrigation purposes. Unfortunately, too much pumping will deplete the natural water underground and lead to shrinking.