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HCMUS researchers combining electrical resistivity surveying with ground-penetrating radar to improve the reliability of survey results.

Nearly six decades have passed. Many traces of war have been obscured by time and changing landscapes, yet the search for those who gave their lives in service of the nation has never ceased. Through ground-penetrating radar (GPR) and advanced geophysical methods, researchers from VNUHCM–University of Science (HCMUS) are contributing scientific evidence to support the search for and recovery of the remains of fallen soldiers, demonstrating how present-day scientific knowledge can honour history through gratitude, responsibility and professional dedication.

Since June, a team of specialists from HCMUS has worked alongside relevant authorities to conduct surveys across three areas within Le Thi Rieng Park, Ho Chi Minh City, covering a total area of approximately 2,500 square metres. Survey locations were identified through historical records, eyewitness accounts and findings from previous studies.

At each site, researchers employed both ground-penetrating radar and electrical resistivity surveying to investigate areas requiring further examination and verification. Geophysical data collected in the field were subsequently processed using specialised algorithms to reduce signal noise, generate geological cross-sections, produce anomaly maps and construct three-dimensional subsurface models. Analysis of these datasets enables the research team to identify locations displaying characteristics that differ from surrounding geological conditions. Such findings provide valuable scientific evidence for delineating priority areas, cross-checking historical information and recommending locations for further field investigation.

According to Assoc. Prof. Lê Văn Anh Cường, Head of the Department of Geophysics, Faculty of Physics and Engineering Physics, HCMUS, ground-penetrating radar operates by transmitting electromagnetic waves into the ground and analysing wave propagation, reflection and scattering as signals encounter materials with different dielectric properties. During field surveys, the system continuously emits electromagnetic pulses beneath the surface and records reflected signals from geological layers or anomalous subsurface objects. Careful processing of these reflected signals enables specialists to identify variations in geological structures and determine the locations of features requiring further investigation.

Assoc. Prof. Lê Văn Anh Cường explained that, in the search for the remains of fallen soldiers, ground-penetrating radar does not directly detect human remains. Instead, the technology identifies traces associated with historical burials. Such indicators may include disturbed soil resulting from excavation and backfilling, disrupted geological boundaries, metallic objects such as canteens, firearms, ammunition casings or personal belongings buried alongside the deceased. Long-term changes in soil structure and gradual ground subsidence may also produce electromagnetic anomalies that can be detected by radar. Once processed and analysed, these anomalies help identify locations that should be prioritised for field verification.

Compared with large-scale exploratory excavation, the use of ground-penetrating radar enables authorities to narrow search areas before excavation begins, significantly reducing time, labour and cost. In many cases, preliminary analysis of field data can also be completed on site, supporting initial decision-making. According to Assoc. Prof. Lê Văn Anh Cường, however, locating mass burial sites created almost 60 years ago presents considerable challenges. Urban development, land reclamation and changes to terrain have left many targets buried much deeper than the original ground surface. Decades of burial have also caused physical traces to weather gradually and merge with surrounding geological materials, reducing the strength of reflected electromagnetic signals. For that reason, successful investigations depend upon the integration of advanced technology, specialist expertise and reliable historical evidence.

Assoc. Prof. Lê Văn Anh Cường emphasised that recommendations for site delineation or excavation are never based solely on radar data. Survey findings must be examined alongside historical maps, archival records, eyewitness testimony and results from complementary investigations. Only locations supported by multiple lines of evidence are prioritised for field verification or archaeological excavation. Alongside ground-penetrating radar, the research team continues to integrate additional geophysical techniques, including electrical resistivity tomography (ERT), electromagnetic sensing, shallow seismic surveys, three-dimensional mapping, unmanned aerial vehicles and artificial intelligence to improve confidence in survey findings.

Survey work conducted at Le Thi Rieng Park represents the latest stage in a series of initiatives undertaken by HCMUS to apply geophysical technologies to the search for and recovery of the remains of fallen soldiers. Under Official Dispatch No. 5144/VPCP-KGVX issued by the Government Office, ˮ����AV��˵ National University Ho Chi Minh City (VNUHCM) and VNUHCM–University of Science (HCMUS) were tasked with mobilising specialist researchers and advanced equipment to support survey, search and recovery operations across southern ˮ����AV��˵ through July 2027. The first operation was carried out in Quang Ngai Province, along Truong Chinh Street, where historical evidence suggests the presence of mass burial sites containing the remains of approximately 70–90 soldiers who lost their lives during the 1968 Tet Offensive.

The continued application of advanced geophysical technologies to the search for the remains of fallen soldiers demonstrates the research capability and technology transfer capacity of scientists at HCMUS. More broadly, such work illustrates how science and technology in ˮ����AV��˵ are making increasingly meaningful contributions to missions of profound historical significance and humanitarian value.

CTV