One of the reasons that the explosives have not been removed was the unfortunate outcome of a similar operation in July 1967, to neutralize the contents of the Polish cargo ship Kielce, that sank in 1946, off Folkestone in the English Channel. During preliminary work, Kielce exploded with a force equivalent to an earthquake measuring 4.5 on the Richter scale, digging a 20-foot-deep (6 m) crater in the seabed and bringing "panic and chaos" to Folkestone, although there were no injuries.[5]: 2000 survey, p21–22  Kielce was at least 3 or 4 miles (4.8 or 6.4 km) from land, had sunk in deeper water than Richard Montgomery, and had "just a fraction" of the load of explosives.[10] According to a BBC News report in 1970,[12] it was determined that if the wreck of Richard Montgomery exploded, it would throw a 300 metres (980 feet)-wide column of water and debris nearly 3,000 metres (9,800 feet) into the air and generate a wave 5 metres (16 feet) high. Almost every window in Sheerness (population circa 20,000) would be broken and buildings would be damaged by the blast.