Why Would Seismic Testing Happen Inside City Limits?
An article in The Marietta Times (Marietta, Ohio) does an excellent job of describing the process of seismic mapping recently performed in the City of Marietta. Having a map of underground structures—how the rock formations and layers are arranged—is worth millions to drillers. So they hire companies to create maps.
Cables are laid along side roadways and a truck moves along “stopping at regular intervals to lower large vibrating metal disks from each truck onto the road surface.” The cables record seismic vibrations and create a 2-dimensional map of structures under the surface.
The initial 2-D mapping shows what’s happening directly beneath the road. If companies see areas that pique their interest, they then order a 3-D map, a more involved process. But they hardly ever (perhaps never) order 3-D maps for cities because drillers typically don’t want to deal with signing hundreds or thousands of individual landowners over a relatively small area. So the question is, why were seismic trucks doing 2-D mapping inside the city limits of Marietta if no drillers would ever want to drill there?