Recent news coverage of archaeologists investigating the ground got me thinking about using their method in forensic investigation. It’s called ground penetrating radar, GPR for short. It sounds technical but it’s not really. It’s simply a radio transmitter and a receiver.
The device sends radio waves into the ground, processes their reflection from a buried object and displays the results on a computer monitor. The display is analysed and the nature and depth of the object is determined. Airports send radio waves out all the time to identify your inbound flight from Toronto and how near you are to landing.
GPR is used to look for objects of interest below the ground surface. Things like old skating rinks, stone walls and graves as reported in the news stories on archaeological work at the Halifax Commons and Grand Pre in Nova Scotia and at Sydney Mines in Cape Breton. (Refs 1 and 2) The work on the mainland is by Jonathan Fowler, Saint Mary’s University and in Cape Breton by Maura McKeough, Parks Canada. GPR can also be used to identify the depth to the water table, different layers of soil and rock and voids in the ground.
There was a news report a while ago about a house in Nova Scotia collapsing into a void. GPR could be used to locate voids like this before a house was built.
i used GPR during an engineering investigation in the Bahamas looking for voids in the limestone beneath an airport runway. The voids are called banana holes. I understand they got this name because banana plants grow there when the roof of the void collapses exposing it at the surface of the ground, or a runway. The voids form when ground water dissolves the limestone.
You can imagine the civil litigation that would result if an aircraft on landing caused the roof of a banana hole to collapse and the aircraft to crash. Particularly considering the ready availability of remote sensing methods like GPR to locate voids.
These methods are remote sensing – non intrusive – like CAT scans, X-rays and Ultrasound in medicine. No surgical cutting a patient ‘s body to see the tumor and no digging in the ground to see the void.
On a personal note, my re-awakened interest in this method was also its possible use in locating the unmarked grave of my baby sister in a cemetery in New Brunswick. My mother had a 7.5 month premature baby – Baby Hazel – who died 2.5 days after she was born. My sister’s casket would display on a GPR monitor as an unusual feature in the soil.
I don’t know when the need to use GPR during a forensic investigation will arise but I’m certain it will. I can imagine it resulting in a more cost effective forensic investigation in some instances as well. Almost any civil litigation involving the ground might be a candidate.
i chanced to see a drone fitted with a camera taking low level, aerial video several years ago and now consider getting aerial video with a drone of all my forensic sites involving the ground. Who knows when and where ground penetrating radar, GPR, might be useful during a forensic investigation?
- Fowler, Jonathan, professor of archaeology at Saint Mary’s University, Halifax, NS as reported in The Chronicle Herald, Halifax, Saturday, July 18, 2018
- McKeough, Maura, cultural resource manager, Parks Canada as reported by CBC June 29, 2018