What goes bump in the night? We do.

Steve Harder prepares to detonate a shot.

Controlled blasts in deep holes are the source of sound waves for our program.  We set them off in the middle of the night because that is when it is quietest along the county and state roads where our instruments are shallowly buried on profiles across eastern Georgia and listening for sound waves.  During the nights of Aug 7, 8 and 11, our blasting experts Steve Harder, Galen Kaip and Ashley Nauer prepped and detonated 25 blasts along our lines, with some help from other enthusiastic scientists (like me).  Our shots have between 200 and 1600 lbs of explosives – mostly ammonium nitrate emulsion. At each shot, we connect a long wire between the drill hole and a blast box, move back a safe distance from the shot site, wait for the appointed time, and set off the blast. The blast box is used to detonate the shot at a very accurate time. There were two shooting teams, and each has different time windows for blasting to ensure that we only do one blast at a time. If two blasts occurred at the same time, the sound waves could interfere with one another.

Ashley Nauer and Kent Anderson wire up a shot.

When the blast goes off, you feel it more than hear it.  The sound waves radiate out from the shot traveling both within the earth and along the surface. Waves that travel along the surface of the earth (“surface waves”) cause the most ground shaking. If the ground is wet, sometimes a geiser briefly occurs 5-10 seconds are the explosion.  Not surprisingly, plenty of people are interested in experiencing this besides us!  Several of the property owners who very kindly gave us permission to set off these blasts on their land came out in the middle of the night to spectate.

Even putting aside the obvious rush of setting off a bunch of blasts, its fun to be out and about in the Georgia country side at night.  A cacophony of sounds echo around the forests from crickets and frogs.  Immediately after a shot, all of these creatures very briefly go silent – they know that something has happened! And then they ramp up again.  We also see other animals prowling around, including amardillos. A meteor shower occurred during our final night of blasting, which we could see quite well from the rural stretches of Georgia, far from light pollution of population centers.

Donna Shillington, LDEO

Jim Gaherty illuminates a steaming hole that formed over the shot site from the blast.
The shot team filled in this hole the next day.

Armadillo patrols one of shot sites.