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Well done to all who participated in the Giant Jump! We have received huge media coverage, broken two world records, and set Science Year off to a rocking start, but what about the geological effects of the experiment? • Effects of the Jump • Seismic Networks • Seismometers • Results Effects of the Jump During the Giant Jump all those record-breaking people jumping across the country caused the ground to shake. If you tried any of our simple ways to detect ground vibration – such as balancing rulers on the edge of tables to see if they fall off or looking for waves in a paddling pool – you may have noticed some surface effects of the Jump. Seismometers are devices that measure any vibrations in the ground. They can be designed to pick up vibrations much smaller and deeper into the ground that the vibrations we can normally feel or see on the surface. You may have made one or more of the seismometers from our website. Or you may have been lucky enough to see one of the seismometers lent to the nine Science Year launch venues by local universities and seismometer manufactures Guralp. The effects of the Jump shouldn’t be limited just to the area people are jumping in. If you place a cup of water at one end of a table and hit the other, you’ll see the water wobble as the impact you made by hitting the table travels down through its body. We should observe something similar with our jump. That is, if one of the schools participating in the Giant Jump had caused an earthquake in their playground (no one so far has reported one!), it would have sent out waves of energy across the Earth, called seismic waves. The distance these waves can travel depends upon the type of waves they are. The type of waves created by the Giant Jump were of a very high frequency, which meant they could not travel very far before dying out. You can see how far your jumping-waves travel by getting a line of people to lay on the ground (outside) while another group jump up and down nearby. The people lying on the ground will feel the Earth shaking if they are close to the jumpers. Those further away won’t feel the vibrations so strongly as the wave dies out before it gets to them. So that Science Year knows exactly how far its waves did travel, we have contacted groups with highly sensitive seismometers in Australia, Japan and the USA who can prove whether our waves were too high frequency to travel to them. Seismic Networks For the Giant Jump, Science Year linked up with several networks of seismometers. We know that many of you made your own seismometers from the instructions on our website because we’ve seen your photos! We also had the seismometers at our launch venues: - Wellcome Wing, Science Museum, London - BAe Systems at Warton - The Eden Project, Cornwall - Life Interactive World, Newcastle - Think Tank, Birmingham - Explore@Bristol - W5 Discovery Centre, Belfast - Techniquest, Cardiff - Glasgow Science Centre, with the BA Festival at Glasgow University  Murray McGowan from Guralp with Science teacher and TV presenter David Bromfield in the Wellcome Wing, Science Museum, London. From the seismometer at Explore@Bristol the Geologist there predicted that the jump there was equivalent to one hundreth of an average earthquake! Guralp seimometers are particularly sensitive. They can pick up vibrations that are not detectable by people. Science Year would like to thank Guralp for their huge amount of help in measuring the Giant Jump. Science Year also linked up to the permanent seismometers already located across the UK to trace the Giant Jump’s waves. You’ve probably passed these seismometers without even noticing. Below is a picture of a typical outstation for a seismometer (which collect the information from seismometers on computer)  |
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 This map shows the 140 seismometers that make up the British network. Different geological groups use different sub-networks of seismometers. all of which are part of these 140. The British Geological Survey’s offices in Edinburgh can read results from all of them at once. This was the office that Science Year looked to for the results of the Giant Jump. Each seismometer monitors seismic activity in their locality. The last networks of seismometers Science Year are using are international ones, as we look at results of seismometers from locations around the world. We have already contacted several international seismic stations to ask them to look out for any odd readings around 11am BST on the 7th of September. |
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| Seismometers There are many components that go into a really good seismometer. However there are a few important features that you should know. 
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As the Earth shakes, the seismometer does too. However, the magnetic mass is stable enough to stay relatively motionless, with the coils moving around it. As the coil moves back and forth along the magnetic mass it breaks the lines of magnetic force, thereby generating an electric current. This is very like the solenoid sensor you can make from instructions on our site.  This current is usually converted into FM radio waves. The picture on the right is of an outstation mast, which sends the waves to a base station where they are recorded on a computer hard drive.Results The experiment was a huge success – with lots of people recording how the ground vibrated locally. Seismologists in Bristol calculated that the vibrations caused were equivalent to 1/100th of an average earthquake. Thank you to all the people who have sent in their seismometer results. Many of the homemade seismometers have worked really well, and we will be showing some of the traces, and photographs here next week. We will also be showing the results from some of our on site seismometers. Please let us know about your school’s Giant Jump results! Send us your seismometer results or photographs to 11 Tufton Street, London SW1 3QP, remembering to include the name and address (or Giant Jump reference number) of your school. Although over 1 million people were jumping the vibrations created did not get recorded by the UK seismic network. This is because the vibrations were high frequency surface vibrations which are quickly absorbed in the earth. However the local effects of all that jumping was measurable and we will be publishing the results soon. 
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