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Last Updated: Friday, 28 March 2008, 06:26 GMT
All of a tremor inside Blacknest
Gordon Corera
Security correspondent, BBC News

Blacknest. Picture courtesy of the Blacknest website.
Blacknest was set up in the early 1960s
From the outside, it looks like a large house in the Berkshire countryside and, as you pull up outside, there are few outward signs that the building, known as Blacknest, is actually part of Britain's Atomic Weapons Establishment (AWE).

But, all becomes clear once you enter the building situated separately from the rest of the highly secure AWE facility.

The unusual nature of the work going on inside is soon revealed when Peter Marshall, a scientist who has been working at Blacknest for more than four decades, walks me into a room and demonstrates a device revealing the tiny tremors produced by my car pulling up out front and from my footsteps entering the room.

The movement is recorded by a seismometer - essentially a mass on the end of a spring which is sensitive enough to measure tiny movements.

Boxing day tsunami

The one inside Blacknest is just for demonstration - the UK's main array is located hundreds of miles north, in Scotland at a place called Eskdalemuir.

Here, among the rolling moorland, are a series of small pits laid out in the shape of a cross. Inside the pits, about 7ft underground sit the seismometers.

The government would expect us to come up with the precise origin time, a location, and an independent assessment of the size of an event
Peter Marshall, scientist

Their sensitivity is quite astounding. If a mine goes off in the harbour all the way down in Portsmouth on Britain's south coast, the machines are able to detect the tiny tremors produced.

A 1,000-tonne explosion taking place 3,000kms away actually still generates a signal in this country of about 1 nanometre - 1/50th of the diameter of the flu virus.

Even a 25-tonne explosion in the former Soviet Union can be detected.

And when the tsunami hit on Boxing Day in 2005, the earth in the UK actually moved by 15mm.

International monitoring effort

Blacknest was set up in the early 1960s to house a group of scientists charged with trying to develop techniques to identify nuclear explosions anywhere around the world, whether happening in the atmosphere, underground or underwater.

It was vital to be confident about detecting explosions in order to make arms control agreements work.

Peter Marshall
Peter Marshall has worked at Blacknest for more than 40 years

Their effort continues to be directed at detecting explosions as part of a wider international monitoring effort.

The Comprehensive Test Ban Treaty has yet to come into force but countries are abiding by its provisions.

There are an array of monitoring stations around the world to detect any tests and their data is fed into a central hub in Vienna from where scientists can then extract what they need.

As well as seismology data, there are also monitors to detect hydro-acoustics and infrasound signals.

Using the global data, scientists at Blacknest are able to provide the government with fast assessments.

"The government would expect us to come up with the precise origin time, a location, and an independent assessment of the size of an event," explains Peter Marshall.

This happened most recently when North Korea conducted a test in 2006.

Buncefield was really quite interesting because a lot of people in the area around Blacknest, actually, their windows rattled
Peter Marshall, scientist

The system of monitoring is designed not only to be able to find out if someone has tested but also to act as a deterrent to countries by making it clear that they cannot conduct clandestine tests.

When the seismometers detect a movement, the challenge is trying to work out whether it is the sign of an explosion or an earthquake, a science which Blacknest has been at the cutting edge of development.

If it is an explosion, the next challenge is to try to distinguish between a large conventional underground explosion and an actual nuclear explosion of the same size.

In order to do that, you need to look for evidence of radio-nuclides, a tell-tale signature of a nuclear event.

The technology developed at Blacknest is also being put to much wider uses.

The expertise in seismology housed there has been used to investigate many non-nuclear events, including the Lockerbie plane crash in Scotland which occurred near the UK seismometer array.

The team was asked to try to establish whether there had been an explosion on board or just on impact.

They also investigated events including the sinking of the Kursk in Russia and the Buncefield explosion in the UK where the team was able to tell exactly how many explosions had taken place.

"Buncefield was really quite interesting because a lot of people in the area around Blacknest, actually, their windows rattled," explains Peter Marshall.

"Blacknest would have made a complete assessment which was then passed to the government."

Clouds of ash

Data on the epicentre of earthquakes, and future tsunamis, can also be provided to help rescue teams.

It can also be used for detecting volcanic eruptions. This has important applications for aircraft which might be flying over an eruption.

One recording played to Blacknest visitors includes a conversation between a KLM flight and air traffic control when this happened.

It reveals just how dangerous it can be as the ash cloud caused the engines to fail and the plane to plummet until it eventually recovered.

The international monitoring systems can provide early warning of such an event.

For Peter Marshall, and others working at the facility, using their knowledge and technology for wider applications has huge potential whether predicting atmospheric behaviour or finding out more about global warming.



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