Looks like they're doing a seismic survey. They're typically contracted by an oil company (E&P). The shock waves travel at different speeds through different rock formations, so the petroleum geologists can identify any faults or grabens and adjust the wellbore placements accordingly. They can pair the seismic model with the geology model from the mud logs, etc from other wells in the area and get a pretty good picture of what's going on 7000' below surface.

As far as where they got permission to be working out there, I'm sure it's covered in the land use agreement between the landowners and the E&P.