ERTH 2415 Lecture Notes - Lecture 13: Low Frequency, Nomogram, Seismogram
28 Aug 2018
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Document Summary
Earthquakes: earthquake occur when two plates come together, but and faults they are going to lock up, earthquakes are caused by sudden movements along faults. How are seismic waves recorded: seismometer: sensor that detects ground motions, seismograph: an instrument that records ground motions, seismogram: paper record or digital file with data describing ground motions. Seismic waves: two types, body waves: propagate through the whole body of the earth, large earthquakes generate body waves recorded all over the world, surface waves: propagate only near the earth"s surface. Surface waves from the p waves: low frequency, slow velocity, very large amplitude, low attenuation, high amplitude long duration wavetrain potentially causing considerable damage. Arrival time: time at which a particular seismic wave is recorded by a seismometer, p and s waves low amplitude, surface waves high amplitude wavetrain, p and s waves high frequencies. Magnitude: surface waves low frequencies, amount of energy released during an earthquake, basic principle, larger the earthquake.
