Reading a Seismogram ```Name: N/A Status: N/A Age: N/A Location: N/A Country: N/A Date: N/A ``` Question: I have a seismograph of my own construction connected to computer I get neat recordings but I want to read car and truck patterns. How can I quantify my readings to "prove " a reading is a car? Replies: You have a hypothesis -- "a seismograph will respond differently to a car than it will to a truck." Now you need to perform experiments to determine the validity of your hypothesis. Take data while observing whether you are detecting a car or a truck. Compare the results and see if there are any obvious differences -- e.g., different amplitudes, noise levels, frequencies, etc. You may want to try doing a Fourier transform of your data to see if certain frequencies are characteristic of one type of vehicle or the other. To do this job thoroughly you will want to take account of things like vehicle speed and road surface. Once you have done these experiments you may be able to refine your hypothesis to be something like -- "trucks (18 wheelers) have an enhanced signal at XXX hertz in the seismograph signal, relative to cars." Then you can perform more experiments to verify this and even quantify it -- for example you may find that cars have a signal intensity less than YYY at XXX Hertz while trucks have a signal intensity of ZZZ at the same frequency. There is a lot of work involved but building the seismograph must have taken a lot of work too! Your problem is very interesting and I would be interested in hearing how it turns out. Keep us informed! gregory r bradburn Click here to return to the Physics Archives

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