Detecting the minute vibrations caused by earthquakes that happened thousands of kilometres away with a simple piece of equipment sitting in your own school creates a 'wow' moment for students — and sometimes staff as well. The instruments required to do this are surprisingly simple — and some can even be made by teachers in a school workshop.
The SEP seismometer system is a horizontal seismometer that uses electromagnetic induction to detect ground motion (velocity) and eddy current damping.
Available from Mindsets UK for £445 + VAT.
Over 500 of these instruments have been purchased since 2007.
Mindsets also sell the electronics package (x100-500 amplifier, 0.013-5Hz filter and 20sps 16bit digitiser) seperately for £109 +VAT which can be used with your own homemade sensor.
The Rockwave VS1 is a compact, vertical motion seismometer,designed for education and the keen amateur intending to set up a home observatory. As a vertical instrument it is almost insensitive to ground tilt. The electronics are integral, the mechanics are visible, and the capacitance displacement sensor can be examined by removing the end cap. The VS1 is compatible with AmaSeis and isalso supplied with a full manual and software utilities in Basic.
Available from Rockwave for £526.
Rockwave are not VAT registered
The Department of Earth Sciences at Royal Holloway, University of London have written a short report on direct comparison of the SEP and Rockwave sensors.
US company Infiltec produce a "black box" seismic sensor based on using a small geophone. This is a small vertical sensor which lacks the sensitivity or low frequency response of other designs but is very robust and easy to install, it is compatible with Amaseis/Jamaseis datalogging tools. Infiltec do not have a UK distributor but the sensors may be ordered direct from their US website for $295 +taxes +shipping
A very simple seismometer can be constructed at home from just a mass on a spring with a magnet and coil as a transducer. Seismometers need to detect very low frequency signals to record earthquakes and to do this with a mass-spring arrangement you either need a very heavy mass or a very weak spring so that the natural oscillation frequency of your mass-spring system is lower than the signal you are trying to detect. Mini-slinkies work well as weak springs and Mindsets sell a seismology modelling kit which includes a suitable coil and magnet. Boise State University in the USA have refined a design for the slinky seismometer, or you can simply construct one yourself at home. The sensor will interface with the electronics package provided by Mindsets.
Guralp Systems are the world's largest manufacturer of professional seismometers.
They also make a version for use in schools. The Guralp CMG-EDU system includes an EDU-V vertical broadband seismometer and CD24E1 compact digitizer, with a robust GPS unit for timing.
This uses the same force feedback technology to detect ground motion as professional seismometers and produces calibrated data with GPS synchronised time stamps that can be used by researchers around the world.
The system costs approx £1000 per unit and is in use by three schools in the UK.
Many consumer electronics goods now use microchip MEMS accelerometers to detect motion e.g. iPhones, Wii controllers and 3D mice. These MEMS accelerometers can be used to detect ground motion. At the moment they are not sensitive enough to detect signals from distant earthquakes, however if an event happens nearby the data that they record can be quite useful.
Basic MEMS accelerometer with USB interface such as the JoyWarrior24F8.
iPod touch and iPhone have several applications which turn the devices into a seismometer.
Apple laptops have an accelerometer built into them which can be used as a seismometer — SeisMac 2.0
The Quake-Catcher network makes use of computers fitted with either inbuilt accelerometers (Apple laptops or IBM Thinkpads) or PCs with JoyWarrior USB accelerometers to act as strongmotion seismometers. A background process monitors activity from the accelerometer. Each time an event is detected the results are collected by the Quake-Catcher control centre at Stanford University. This is effective for measuring the large signals from nearby earthquakes on thousands of home computers.