Seismometry as an Introduction to Experimental Design and Data Analysis

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Seismometry as an Introduction to Experimental
Design and Data Analysis

• Dr. Thomas A. Dooling
• UNCP

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Amature Seismometry is an active area

• http//www.seismicnet.com/lehmntxt.html
• http//users.viawest.net/aloomis/seismom.htm
• http//www.seismicnet.com/dave/map.htm
• http//cse.ssl.berkeley.edu/lessons/indiv/davis/hs
  /Seismograph.html
• http//jclahr.com/science/psn/index.html

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Seismometry serves as introduction to,

• Geophysics
• Mechanics (damped oscillator design)
• Basic electronics (amplification, filters)
• Fourier Transforms
• Sonification of data
• Data visualization
• Cheap!

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Basic Design

• Seismometer is ideally a large inertial mass
  floating in space! The world moves about it.
• In practice, an inertial mass attached to a long
  period oscillator.
• Requires something to sense the displacement or
  movement of the device.

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Simple Pendulum Design
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Long Period Lehman DesignJuly, 1979 Scientific
American "The Amateur ScientistHow to build a
simple seismograph to record earthquake waves at
home by Jearl Walker Designed by James D. Lehman
of James Madison University
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My own quickie design from stuff lying around
the lab
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Pendulum Diagram
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Equipment List

• Pick-Up Coil
• Neodymium Magnet
• Op-Amp/Resistors
• Pasco Interface
• Voltage probes
• Meter Stick, Stand, Wire

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Simple Op-Amp, RC Filter Circuit
Gain 5000/22500
Period Cut Frequency 1/(2?RC)
Inverting Amplifier
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NOISE !

• The window of an office is mechanically and
  electromagnetically very noisy!
• However, there is one major seismic event that
  stands out well above the noise.

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A Train
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Spectrum of Train Going By
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Fourier Transform of Train and Background
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Typical Night Run(Started at 430 pm, Oct. 25
2005)
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Example of One Train(from night run)
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Sonification of Data( sound file)ascii file
converted to wav format by,TDL Technology,
Inc. http//www.tdl-tech.com/download.htmasc2wav
.exe
200 times faster
100 times faster
50 times faster
25 times faster
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Different Train (Oct. 28)
200 times faster
100 times faster
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Next Step

• Find some place quiet ..
• Improve design (more sensitive)
• Better amplification
• Develop new designs
• Build Infrasound detector!
• JAVA applet