A tidal wave of huge proportions could hit central London at any time, causing untold loss of life and property. Authorities are worried that the threat is getting closer and closer. The danger does not come from freak weather conditions or outlandish earth movements. It is far more mundane and immediate.
The wreck of the SS Richard Montgomery lies in the Thames Estuary filled with enough explosives to bring down the city. The American cargo ship was carrying over six thousand tons of explosives when it grounded and broke in two off Sheerness in 1944. Much of that ordinance is still on the wreck, and the coastguard have warned that there is a serious and growing threat of significant structural collapse of the shipwreck.
If she blows, it will send a tidal wife sweeping up the Thames, which will overwhelm the Thames Barrier. The port of Sheerness would be wiped out within minutes.
The 420-foot-long cargo ship was built during the Second World War, and launched in June 1943. A little over a year later, August 1944, she left Philadelphia with 6127 tons of munitions. She was bound for the Thames Estuary, where she would join a convoy heading for Normandy to restock the troops who carried out the D-Day landings.
The Mongomery anchored off the north edge of Sheerness middle sands. But on August 20, she dragged anchor and began to drift. Several ships spotted the danger and tried to signal an alert by sounding their sirens. Captain Wilkie slept through the racket, and his chief officer unaccountably did not try to wake him. The ship subsequently ran aground on a sandbank around 800 feet from the Medway Approach Channel in 24 feet of water. The ship broke her back on the sandbank.
A salvage company tried to remove the cargo and got much of it off before the hull cracked open and the holds flooded. The ship broke in two and the ship was abandoned with half the cargo still on board. This included 1400 tons of high explosive.
As the Richard Mongomery poses a real danger to shipping, the wreck is constantly monitored and a warning buoy marks the site. Part of the superstructure of the vessel remains visible above the water. In 1973, the site was the first wreck to be designated as dangerous, and as such, there is a constantly policed exclusion zone around it.
A risk assessment is carried out periodically. After one in 1999, the port authorities said that “Doing nothing is not an option for much longer.”
According to a survey conducted in 2000 by the Maritime and Coastguard Agency, the wreck still contains 3173 tons of munitions. Removing the explosives would be dangerous. An attempt was made to salvage a similar cargo ship off Folkestone in 1967. The explosion on that occasion had the force equivalent to an earthquake of 4.5 on the Richter scale, punching a 20 crater in the seabed and bringing panic and chaos to Folkestone.
The Richard Mongomery lies in the estuary rather than in open water. Rxperts agree that if she blows, it would throw a 1000 feet wide column of water, mud, metal and munitions nearly 10000 feet into the air. It would generate a wave 16 feet high which would sweep up the estuary.
As the river narrows near the capital, the wave would groe in size. Couple that with a Spring Tide, and London could become the Venice of the north in minutes. The initial blast would blow out almost every window in Sheerness and the wave a few minutes later, would level much of the town.
How likely is the catastrophe? Some experts say a fuse in one of the fragmentation devices could becom unstable as its lead azide reacts with water vapour to form hydrazonic acid. This could then react with copper in the detonating cap forming an extremely sensitive copper azide. A knock, perhaps caused by the ship breaking up further, or a collision with a passing boat, could cause the copper azide to explode triggering a chain reaction resulting in the detonation of the bulk of the explosives.
The government however feels that the danger is exaggerated, and that much of the dangerous chemicals in the fuses will have dissolved in the seawater by now. However, no one knows for sure.
Surveys in 2008 and 2009 show that the ship continues to deteriorate, and is breaking up faster by the year. The Coastguard Agency said that a 2009 structual survey showed “accelerated deterioration”. Its report concluded that collapse was not imminent but getting closer. It went on to say: “At some point in the future, there could be a complete loss of structural integrity in hold number two possibly leading to this section breaking in two.”
If the ship explodes, it will one of the biggest non-nuclear blasts ever, the equivalent of a one kiloton nuclear bomb and will devastate the port of Sheerness. It will do more damage to London that the Great Fire of 1666.
The Richard Mongomery carries the explosive equivalent of a small 1.4 kiloton nuclear device and it lies in the Thames Estuary menacing London. Its deadly cargo still includes roughly 1400 tons of TNT. It is made up of the following:
286 x 2000 bombs
4439 x 1000 Lb bombs
1925 x 500 Lb bombs
2815 x fragmentation boms
Various smoke bombs including white phosphorus bombs.