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The natural logarithm of the ratio of two amplitudes is measured in nepers. By definition, if Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") One bel 10 decibels (dB), and energy is proportional to (amplitude)Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Let Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.")
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The concept of a reflection coefficient is fundamental to reflection seismology. A negative reflection coefficient implies phase inversion, that a compression is reflected as a rarefaction. Where displacement is measured with respect to a space-fixed coordinate system (e.g., if positive means downward displacement), the signs differ from this. In the more general case of a plane-wave incident at an angle, both reflected P- and S-waves and transmitted P- and S-waves may be generated. The amplitude of each of these waves may be found from Zoeppritz's equations (q.v.) (or Knott's equations).
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In earth science related fields, geophysics deals with surveying potential, diffusive and wave fields in order to obtain structural information of the subsurface to characterize earth's layers in terms of its physical and geological properties. Examples of potential methods are: gravimetry, magnetometry and electric resistivity methods. Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Among these potential fields, gravity and Magnetic surveys are routinely carried out over vast stretches of land or sea, thus are characterized by wide coverage but poor resolution, being the least expensive and the most commonly used in mineral and oil exploration.
- Geophysics > Gravity Surveying (1.00)
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- Information Technology > Knowledge Management (0.76)
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Figure 9.32a shows three reflections before and after normal-moveout removal. Explain the broadening of the wavelets produced by the NMO correction. A causal wavelet has zero amplitude for negative time, that is, when Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") A normal-moveout correction is subtracted from the arrival times of a reflection to compensate for the increase of raypath length with offset. The normal-moveout equation (4.1c) has the factor Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.")
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A source is offset 3.00 km west of a vertical well in which a geophone is suspended. There is a vertical north-south fault 0.80 km west of the well with velocities Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") A horizontal reflector is present west of the fault at a depth of 2.00 km. Find the reflection traveltime for geophone depths of 0.60 and 1.20 km. This problem must be solved by trial-and-error methods, either graphical or numerical.
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Land cables are built in sections that are identical. The connections to plugs at each end of the section effectively rotate the system by the number of groups to be connected to the section. Thus, if pins 1, 2, and 3 at one end of the section are connected to takeouts for 3 groups in a section, at the other end of the section they will connect with pins 4, 5, and 6 of the next section. Usually there are more sets of wires than channels being used at any one time, for example, perhaps 96 independent pairs of wires for use with 48 channels. However, occasionally so many sections and geophones are laid out that a distant group of phones is connected to the same channel as a nearer group.
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Because velocity analysis is not made on the wavelet onset, how will this effect stacking-velocity values? A causal wavelet has zero amplitude for negative time values, that is, when Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") A normal-moveout correction is subtracted from the arrival times of a reflection to compensate for the increase of raypath distance with offset. The normal-moveout equation (4.1c) has the factor Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") While the value of Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.")
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
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If the error in Shoran time measurements is Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Take the velocity of radio waves as Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") Shoran is a radio-navigation device which measures the 2-way traveltime between the point of observation and a fixed station. Using two fixed stations, the point of observation can be located by swinging arcs centered at the two stations; for large distances the arcs become nearly straight lines. The traveltimes are subject to error Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.")
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For an airwave with velocity of 330 m/s and two geophones separated by 5 m, at what frequency is maximum attenuation achieved? Maximum attenuation is achieved when the waves recorded at the two geophones differ in phase by one-half wavelength. Therefore Failed to parse (SVG with PNG fallback (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.")
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