Several gas exploration companies conducted a series of tests looking for pockets of natural gas. One Saturday morning Rick and I were woken up earlier than we'd have liked by a great deal of noise outside our window. Turns out one of the gas companies was conducting siesmic testing using a helicopter. The helicopter was hovering over the storage units next door while people hooked up a huge sand bag. The helicopter then flew a straight line towards the back of the house and would basically drop the bag to the ground every few feet. I guess the crew on the ground had equipment to measure vibration from the sandbag dropping. I'm not sure how exactly it worked. We didn't manage to get pictures of the helicopter at our place, but a few weeks later they were doing the testing again near Rick's parent's and I managed to get some pictures then:

 

In these you can see the line holding the sand bag. The helicopter flies very very low. Basically when it was at our house it was barely over the roof top.





Here you can see the sandbag.