The use of GPR is often mentioned as a way of locating missing children. Note that although this is a powerful tool, not all missing children will likely be located, even with GPR.
This document outlines what GPR is, how it can be used, and how it is used in ground searches.
What is GPR?
Ground-penetrating radar is one of a group of technologies that can map the contents of the ground remotely and without digging. GPR sends out radio waves and records their reflections, often using a push-cart system. Like navigational radar, GPR distinguishes difference in the reflections, which are then interpreted by an expert. While burials have characteristic reflections and can often be located with GPR, it is more difficult where the background is complex, or the burial is small.
What Role Can GPR Play in Identifying Missing Children?
Many survivors, their families, and communities have knowledge of where missing children are buried. Some archives also contain similar information. GPR can be used when ground searches are conducted. GPR works best when the radar signal is collected carefully – this means that the ground must be clear of debris or tall plants, and the GPR results are collected intensively, usually at intersecting 25 cm lines in grids. The result is a dense pattern of reflected radio waves that allows us to identify places of difference, sometimes called “anomalies” or “targets”. Burials have some characteristic traits in GPR, but researchers are still working out what all of these are and if they change in different landscapes. GPR mostly captures the reflections of the grave shaft rather than its contents.
GPR is sometimes used to scan places where there is no information of burials. GPR is usually used with other information, such as survivor knowledge, information from archives, or within known cemeteries. GPR takes time to conduct and needs special training for both ground searching and interpretation. Courses for Indigenous communities to build this capacity are being developed. GPR technology is also changing and new tools, such as GPR from drones, will likely be available in the coming years.
GPR works as one step in a complex path toward missing children. This path includes supports for survivors, ceremony for communities, and the collection of information about missing children. GPR is not the only scanning tool for ground searches, and only works when ancestors are in burials. Because GPR is a tool for locating missing children, it needs to work with mapping systems such as GIS.
What Are the Challenges of GPR Analysis?
All three main parts of GPR (ground searches, interpretation, mapping) require specialized training and benefit from experience working to locate burials. GPR only works is some kinds of landscapes and conditions. The interpretation of a burial in GPR is complex and builds out of experience. GPR cannot locate children who do not have a burial and cannot confirm the contents of a burial, but only the possible presence of a grave. Our understanding of this tool improves if we share information between communities, but this can be difficult.
