Ground-penetrating radar (GPR) is a technology that can be used to detect buried objects. This type of radar uses electromagnetic waves to penetrate the ground and produce images of what lies beneath the surface.
Can GPR be used to Detect Organic Objects such as Human Remains?
Yes, GPR can and has been used for the detection of buried human bodies. This newer application of GPR has already shown promising results in the field, and it has the potential to revolutionize the way that law enforcement agencies search for missing persons.
When GPR is used to search for buried human remains, it will not be able to detect organic matter, therefore it will not be able to tell whether or not bones exist below.
Over time, bones will absorb the minerals from the soil and become essentially indistinguishable from it.
If the burial is relatively new, a specialist may be able to determine the bones or identify an object that resembles a bone within a few years of it being buried. You won’t see the bones if you’ve got anything that’s 50, 60, or 100 years old unless some special preservation has happened.
Instead, technicians will be looking for soil that has been “turned” or moved in a way that is not natural to it’s environment. Soil has micro layers, and when a shovel is put in the ground and the soil is disturbed and the layers mixed, it becomes different to natural soil next to it electrically and can be spotted by a trained professional.
How GPR Works
The GPR system works by moving a cart-mounted unit across a gridded survey site with the help of a portable linear resonator. A signal produced by the control unit is a continuous stream of high-frequency radio waves that travel through the top levels of the earth.
The reflectivity and rate of return of electromagnetic energy from various materials are determined. Different materials have distinct electrical energy storage or reflection abilities; metal has a high reflecting ability, while dry sand has a low capacity. The data is then displayed as a radargram, which is then deciphered by professionals.
Instances of GPR Being Used to Detect Bodies
A ground-penetrating radar survey was carried out in Cikutra’s cemetery, Bandung. The study was conducted on two adjacent graves that had been buried two weeks prior to data collection.
The survey was carried out with three lines on the grave. The data was sent and recorded using a MALA RAMAC X3M 500 MHz Shielded antenna. ReflexW software was used to process the data.
The radar images from this research revealed hyperbolic reflections, which were coming from the buried body. In comparison to the head and legs of the corpse, the hyperbolic reflection was most powerful in the belly area. The plot displays a high degree of correlation between the processed survey data and the real position of the human body.
Hyperbolic reflection was obtained at around 1.5 meters depth, which is in line with the depth of the buried corpse.
At the Stóra-Seyla farm in Skagafjörður, northern Iceland, separate Viking Age and Medieval churchyards were investigated with ground-penetrating radar.
A survey of a previously unknown area (ca. AD 1000) that was just a few meters above the Skagafjörður valley bottom revealed the remnants of a buried circular turf wall that enclosed a church structure and numerous graves.
The radar scans over the graves show strong hyperbolic reflections emanating from the bones. An air-filled void within the chest cavity was discovered over one grave as a result of abnormal polarity reflections.
In this case, the soil surrounding an intact rib cage crumbled as soon as the excavation began to confirm that there was indeed a hole. The skeletal remains were in excellent condition and produced clear reflections, allowing the body’s orientation to be established.
The radar scans a cemetery from a later churchyard (ca. AD 1200), which displayed ground activity but lacked hyperbolic reflections. Only teeth were discovered during excavation of this tomb. The deterioration of the bone fragments is attributed to exposure to infiltrating water from an overlying gravel layer.
Time-slice overlay imaging, forward modeling and analysis of the reflection coefficient were all used to interpret findings.
In conclusion, GPR can be used to find bodies that are buried along with many other objects hidden deep in the ground. GPR is a non-invasive method that can be used to locate graves without having to dig them up. This really opens up GPR to be used in many different scenarios that would have been restricted otherwise.