Seismometers for Teaching and Research
Seismometers vary from the simplest demonstration unit to complex and
expensive professional instruments used in research. Most commercial seismometers
cost more than $5000 per station to purchase and operational costs can exceed
this each year. For amateur seismologists, teachers and school systems,
this cost is relatively high compared to the cost of other equipment and
hobbies. Hobbyists and teachers can make less expensive instruments, but
it takes some effort to find plans that teachers and hobbyists can use as
a basis for construction. In general, these homemade instruments require
the learning of engineering details and considerable time to care for the
recording of the instrument. This task is made more difficult by the lack
of standards in recording. The object of this page is to document components
that can be combined or used to record earthquakes. The emphasis is on the
low-end of the cost scale, those instruments that a hobbyist, teacher or
school system could afford. The literature is rich in examples of seismic
recorders, but many of the older designs now have better solutions using
more modern electronics and computers.
The list below is not complete, suggestions for inclusion should be sent
A demonstration unit is one that can be used on a desk in a classroom.
The moving elements should be visible and the instrument should not be so
delicate that it could easily be broken in handling.
- Demonstration units are usually homemade and follow simple plans. Many
can be found by a search on the web. These primarily rely on direct visual
observation of movements that the student induces. However, more advanced
models use a simple mechanical or electronic device to write a short record.
They usually utilize oil for damping, the simplest approach, or a copper
plate in a magnetic field, or a damping load resister on the sensing coil.
Horizontal Component Seismometers
The horizontal component seismometer is the most common and is most often
constructed to behave like a swinging gate. Given the proper tilt and care
to reduce friction, an appropriate long period can be obtained. The design
is basically the same as the horizontal component of the long period World
Wide Seismographic Station Network (WWSSN) instrument. George Averill (1995)
describes one version of this in detail. (Averill, George E., (1995). Build
your own seismograph, The Science Teacher, Vol. 63, No. 3., 48-52.). A simple
version can be constructed out of PVC pipe. See
Vertical Component Seismometers
- The vertical component seismometer system uses a spring and magnet
in a coil. Larry Braile [http://www.eas.purdue.edu/~braile/edumod/handseis/handseis.htm]
has described a model
that is easy to construct. The Georgia Tech MAE Center teacher's workshop
constructed a vertical component instrument based
on the principal of the gravity meter.
- Seismographs constructed by amateurs and professionals. There are many
examples of these instruments, usually one of a kind. For many, instructions
for their construction are available on the web or in the literature. Few
of these units have been customized for mass production. A good example
is the STM-8 seismometer built by Sean Morrissey [http://www.eas.slu.edu/People/STMorrissey/index.html]
- AS-1 seismometer is a commercial version of a homemade seismometer.
It comes with a digitizer that uses filters to allow recording of long-period
signals from what is essentially an oil-damped 1.0 Hz vertical geophone.
Allan Jones had written AmaSeis software to continuously record data from
- The nearly Professional units
a) The PS-2 by GEOSense, in California, is appropriate for recording
local earthquakes that are prevalent in California. [http://www.geosense.com/seismometers.html]
b) The CHEAP SEIS system under
development will offer near professional control on response and timing.
C The EIA S-102 [http://www.eaiinfo.com/]
seismometer is a feedback system using linear transformer, [$1600]. This
unit has been adopted by the MichSeis educational program. [http://www.geo.lsa.umich.edu]
- The professional units at low price end
- GURALP PEPPV. Guralp Systems has many high-end seismic systems used
in research. Their special edition PEPPV is a reasonably economical seismometer
that can be use for research. It was one of the original educational seismometers
in the PEPP program [about $2800 plus an old computer] [http://www.guralp.demon.co.uk/]
- PMD systems are three-component systems that use a unique motion sensing
technique The PMD is also one of the original educational seismometers
In the PEPP program [about $4000] [http://home.att.net/~pmdsci/]
- Teledyne Geosciences has developed new broad-band seismometers for
recording earthquakes [$2000 + recording equipment] [http://www.geoinstr.com/]
- Professional quality instruments (typically more than $5000)
- Sprengnether Instruments makes earthquake recording systems and seismometers.
- Geo Space makes geophones and seismometers for many purposes. Their
1.0 Hz units are used extensively in short-period seismic stations. [http://www.geospacelp.com/]
- Kinemetrics. Their 1.0 Ranger seismometer now comes in a broad band
model appropriate for monitoring distant earthquakes. [http://www.kinemetrics.com/wr1.html]