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Seismographs By Danielle Stroup

Seismographs By Danielle Stroup. Definition. Record zigzag trace Detect earthquakes all over the globe Time, location, and magnitude Goal: to accurately record motion. History. Chinese and Egyptians Devices allowed marbles to fall

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Seismographs By Danielle Stroup

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  1. SeismographsBy Danielle Stroup

  2. Definition • Record zigzag trace • Detect earthquakes all over the globe • Time, location, and magnitude • Goal: to accurately record motion

  3. History • Chinese and Egyptians • Devices allowed marbles to fall • 132 AD: Chinese scientist Chang Heng invented seismoscope • Invention called a dragon jar

  4. Seismograph Advances • Modern seismograph invented in the 1800s • 1855: Luigi Palmeri of Italy • Recorded time, intensity, and duration for the first time of small earthquakes • 1880: JA Ewing invents pendulum seismograph • HO Wood and J Anderson: mass suspended by torsion

  5. Mathematical Theory • 1841: Earliest mathematical theory by Forbes • Considered only simple non-oscillatory ground displacements • 1877: Response of a seismograph to arbitrary, periodic, ground motion written in Japan; had little influence on the development of seismographs

  6. Theory • Tilting was neglected in the early development of the seismograph. • Forced damped harmonic-oscillator seismographs were presented by Perry, Ayrton, and Lippmann • Had little effect on the construction of seismographs • 1890's: the importance of tilt was much debated • 1900: become convinced that the effect of tilting could usually be neglected.

  7. Improvements • Press-Ewing seismograph • Records long period waves • Widely used around the world • Press-Ewing pendulum seismograph uses the Milne pendulum

  8. Seismographs • Compact, light weight, battery operated • Performs self-tests • Very detailed computer vibration analysis • Utilized four channels for signals

  9. Blasting seismograph • Monitor, record, analyze, display, and print ground vibration and airblast • Measures seismic wave • Data from blast events represented • Displayed on a liquid crystal display (LCD)

  10. Components • Attached to seismograph to collect data • Vibration sensor (geophone): three sensors • Vibration sensor has internal weight that when moved, creates a voltage • Measures absolute velocity • Microphone to measure airblast

  11. Data • Shows peak particle velocity, displacement, and the frequency of movement • Require different standards and limits depend on the type of structures • Technology is increasingly utilized • Sensors are placed very close to the blast

  12. Conclusion • Instruments have been used for over eighteen hundred years • From seismoscopes to seismographs suitable for detailed studies of earth motion

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