Marcellus natural gas trend Experts believe that these were induced seismicity triggered by disposal of wastewater from Marcellus gas wells into Class II underground injection wells. The Ohio Department of Natural Resources Ohio Seismic Network (OhioSeis) determined that the 2011 earthquakes are distinct from previous seismic activity in the region because of their proximity to the Northstar 1, a Class II deep injection well. All of the earthquakes were clustered less than a mile around the well. ODNR then ordered the company to shut down operations and plug the well. ODNR has continued to report increased seismic activity through 2017 in eastern Ohio in
Seismic anisotropy of 1993-1998 . The early survey does not take into anisotropy into account, while the later survey employs the PreStack Depth Migration imaging. This PSDM was done on a commercial seismic package developed by Total. The following two plots clearly reveal the resolution improvement of the PSDM method. The top plot is a convention 3D survey without anisotropy effect. The bottom plot used PSDM method. As can be seen in the bottom plot, more small structure features are revealed due to the reduce of error and improved resolution. Seismic anisotropy relies on shear waves, shear waves carry rich information which