Determining geophysical responses from burials in graveyards and cemeteries

Abstract

Graveyards and cemeteries around the world are increasingly designated as full. There is therefore a requirement to identify vacant spaces for new burials or to identify existing ones to exhume and then re-inter if necessary. Geophysical methods offer a potentially non-invasive target detection solution; however, there has been limited research to identify optimal geophysical detection methods against burial age. This study has collected multi-frequency (225 MHz – 900 MHz) ground penetrating radar, electrical resistivity and magnetic susceptibility surface data over known graves with different burial ages and soil types in three UK church graveyards. Results indicate that progressively older burials are more difficult to detect but this decrease is not linear and is site specific. Medium-high frequency GPR and magnetic susceptibility was optimal in clay-rich soils, medium-high frequency GPR and electrical resistivity in sandy soils and electrical resistivity and low frequency GPR in coarse sand and pebbly soils respectively. A multi-geophysical technique approach should be utilised by survey practitioners where grave locations are not known to maximise target detection success. Grave soil and grave cuts are important grave position indicators. Grave headstones were not always located where burials were located. This study demonstrates the value of these techniques in grave detection and could potentially date burials from their geophysical responses.