Tojo Vikas International, which surveyed the disputed site in Ayodhya to conclude that there lay a structure beneath, had to call in a geophysicist busy at work in China and airlift to Ayodhya a high-power 100 MHz antenna to conduct a Ground Penetrating Radar (GPR) study. Led by deputy general manager Manoj Kumar, a team of six from the Delhi-based company visited the disputed site between December 30 and January 16. They were aided by their chief geophysicist and adviser Claude Robillard who had to be especially called from an international assignment underway in China. How did they come to the conclusion that there was a structure beneath? In their report submitted to the ASI, 28 pages are devoted to explaining the methodology used and the constraints they faced in reaching the conclusions. What stands out is that it’s a geophysical interpretation and not a survey from an archaeological angle. A GPR survey was conducted using the state of the art GPR Zond 12C which is normally used to provide a graphic image of shallow under-ground features like pipes and sewer lines with high resolutions. How does GPR work? It uses high frequency radio waves to probe the sub-surface without disturbing the ground surface. Radar pulses are transmitted from an antenna and are reflected from underground surfaces. The reflected signals return to a receiver, creating a graphic profile of the sub-surface. First, the area was mapped using Global Positioning System (GPS) and a geo-reference base map was prepared. The field work began with topographical land survey with reference pillars A, B, C, D, E and F. Every prominent feature was marked. The results are reached from surveys conducted in areas based on ‘‘anomalies’’ captured by GPR equipment. The interpretation is superimposed on the survey base maps prepared with GPS equipment. The report lists several constraints faced by the team — running GPR equipment along grid lines marked on sand-baggaged slopes, less space between the tented structure and four-feet high brick wall surrounding the tented elevated platform and broken marble slabs stacked over Ram Chabutra. ‘‘The western area’s steep and unstable slope precluded holding the heavy equipment,’’ says the report. In the end, the report speaks of many anomalies at depths of 0.5 to 5 metres. ‘‘It also appears that those anomalies are not at all contemporaneous,’’ says the report. • Discrete type anomaly: It’s the typical radar signature, for instance, of a pillar or of a wall foundation if crossed perpendicularly. Its radar signal would be a hyperbola shape anomaly due to refraction from the sides of the object. • Multiple reflection: Typical of some flooring, or platform structures made of concrete, bricks or stone slabs. • Hammocky or incoherent sequence: This could be a response of debris zone, rubble of heterogeneous material. • Remains of buried, collapsed dwellings as walls and roof material form piles • It also shows geological layers of undisturbed material at depths ranging from 3-6 metres.
