Shale fracking—the process of extracting natural gas and oil from shale rock formations deep underground—has been linked to an increase in seismic activity in the United States. In Ohio, the town of Mineral Ridge experienced its first 100 earthquakes in 2016 after shale fracking began in the area.

Here's how shale fracking can cause earthquakes:

1. Injection of wastewater: During the fracking process, large volumes of water mixed with chemicals are injected into the shale formation to fracture the rock and release the gas or oil. This injection can cause the earth to shift and trigger earthquakes.

2. Withdrawal of fluids: After fracking, large volumes of fluids, including wastewater and produced water, are withdrawn from the ground. This withdrawal can cause the earth to sink and shift, leading to earthquakes.

3. Changes in pore pressure: Fracking can change the pore pressure in the subsurface rocks. This can lead to changes in the stress field and result in earthquakes.

The increase in seismic activity in Ohio and other parts of the United States has raised concerns about the safety of fracking and its potential impact on communities and the environment. As a result, some states and localities have implemented regulations and restrictions on fracking activities in order to mitigate the risk of earthquakes and other negative environmental impacts.