Digging Dangers

After reading the two articles about drilling in California and Arkansas. There are several concerns that I have that was addressed in these articles. Both articles explained that the disposal of the "salt water" waste was that returned to the Earth's surface. My concern with this process would be the effect on groundwater for people, animals and plants. Another process that was explained in both articles was that the drilling was fracturing rock which would make me think that if you are fracturing rock you are also causing seismic activity through the fracturing. Seismic activity is caused from fracturing of rock whether that fracturing comes from man or nature. This leads me to believe that any disruption in the Earth's surface would cause seismic activity.