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Seismographs record a zig-zag trace that shows the varying amplitude of ground oscillations beneath the instrument. This record is proportional to the motion of the seismometer mass relative to the earth, but it can be mathematically converted to a record of the absolute motion of the ground. These are examples on how seismographs work. Nowadays they are much more modern but the physical principles are the same:
Geophysical equipment used for surface seismic refraction measurement includes a seismograph, geophones, geophone cable, an energy source and a trigger cable or radio link.
What is Seismic Refraction?
Seismic refraction is a useful geophysical method used in the fields of engineering geology, geotechnical engineering, and exploration geophysics. The seismic refraction method utilizes the refraction of seismic waves at the interface between subsurface/geological layers in order to characterize the subsurface geological structure and rock properties.
Seismic refraction utilizes hammer/gun/explosive source at the surface and records earth responses via an array of geophones or hydrophones. The travel-times of first arrivals are derived from the data and then processed to develop 2D/3D subsurface models.
What is Seismic application:
Applications:
• Mapping bedrock tomography and overburden thickness
• Locating buried channels
• Investigating faults, sinkholes and other geohazards
• Landfill investigation
• Estimation of depth to water table
• Estimation of rock rippability
What is technical for seismic seismograph?
Sample stations | 1024, 2048, 4096, 8192, 16384 |
Micro-seismic survey, 1M sampling, several notches | |
Sampling frequency | 10μs, 25μs, 50μs, 100μs, 200μs, 500μs, 1ms, 2ms, 5ms, 10ms, 20ms |
Micro-seismic survey: 1ms~200ms, selectable | |
A/D converter | 24-bit |
Signal stack and amplification | 32 bit |
Dynamic range | 144dB |
Frequency pass bands | 0.1Hz~4000Hz |
Noise | 1μV(full-frequency) |
Amplitude consistency | ±0.2% |
Phase consistency | ±0.01ms |
Lapse-time | 0~9999ms |
Host computer (Industrial PC) |
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PIII 533MHz |
|
EMS memory | 128M |
Disk | no less than 40GB |
CD-ROM | interior |
Display | 800 600 VGA LCD (TFT true colour) |
Input | Chinese character tablet, small keyboard, photoelectric mouse |
Port: | double serial port, one parallel port, double USB port, mouse port, |
keyboard port |
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Flash-Memory | 32M |
Data format | SEG-2 |
Software package | Shallow reflection software |
Rayleigh wave software | |
Micro-seismic collecting software | |
High density and high resolution lateral section survey transaction software | |
Operating temperature | -10ºC~ +50ºC, 90%RH |
Memory temperature | -20ºC~60ºC |
Power | DC 12V 4A (5.5A at 48 channel) |
Size | 400mm×310mm×180mm |
