Seismic activity occurs regularly, primarily due to Earth’s natural movement but sometimes due to the deep injection of wastewater for disposal or other valuable purposes. Far from the catastrophic images of devastating earthquakes that may come to mind, the most frequent seismic activity is imperceptible and even beneficial to the average American. When it comes to hydraulic fracturing operations to recover deep shale gas, seismic activity provides vital information to scientists about the subsurface stresses and permeable fractures. Seismic activity also enhances production and boosts efficiency. Hydraulic fracturing involves rapidly pumping vast amounts of fluid underground, creating and enlarging cracks that provide pathways for natural gas recovery. Hydraulic fracturing operations are designed to take advantage of existing natural cracks – routes that are easily reopened by fluid under high pressure. During the process, scientists record microseismicity – unfelt tremors caused by the movement of brittle rock – to estimate the production capacity, or stimulated reservoir volume (SRV), of a shale gas well.