As fracking activity increases, so have small-scale and medium-scale earthquakes in areas across the U.S. where shale oil and gas are booming industries.

Injection wells used for fracking are suspected to be at the root of more than 2,500 earthquakes recorded in Oklahoma since 2009.

Leftover water is injected into the ground after it is used in the fracking process. This water can travel along fault lines and even make the fault lines larger. It is speculated that this water is affecting fault lines, and thus causing earthquakes.

In Youngstown, Ohio, wastewater injected into the earth was linked to over 100 earthquakes in 2011. In Texas and Colorado, many earthquakes were more than likely caused by wastewater injection in 2011.

Due to the number of earthquakes that have occurred in connection to fracking, the U.S. government is planning to trace the risks from the earthquakes in hopes of better preparing for future building.

Related stories: Texas residents urge action on earthquakes

Via: Think Progress > 2,500 Oklahoma Earthquakes Linked To Fracking, Scientists Say