50 Facts and Terms from my Geophysics Lecture Notes

50 Facts and Terms In Geophysical Exploration
1.       Geophone: a device that measure the arrival of seismic waves
2.       Shot point: is point where seismic waves are sent, a place where explosion generate vibrations into the ground.
3.       Seismic waves: waves or vibrations that travel through the  earth surface, it  is produced by explosives in seismic method.
4.       Seismometer: a device that record the time for the arrival of seismic waves.
5.       Seismic depth: distance between the shooting point and where a wave reflect or refract seismic method.
6.       Explosives: substance used to send seismic waves into ground.
7.       Geophysics: is the probing of the sub surface from the surface using geophysical tools.
8.       Schulemberger array: a configuration with unequal current to potential electrode separation in D.C resistivity method.
9.       Wenner array : a configuration with equal current to potential electrode separation in D.C resistivity method.
10.   Horizontal profiling : a resistivity method of geophysical mapping used in detecting the spread of mineral, water, or oil deposits.
11.   Electrical drilling:  a resistivity method of geophysical mapping used in detecting the depth of mineral, water, or oil deposits.
12.   Apparent resistivity:  Apparent resistivity is the measure of the earth resistivity between two point  which correspond to the sensitivity the ground would have if it were homogenous.
13.   Seismic reflection:  a direct current resistivity method employed in high coastal area seismology e.g oil exploration. It is very expensive and not ideal for shallow depth like ground water, dams etc
14.   In direct current resistivity method, current pass into ground changes potential due to the difference in the resistivity of the ground layers.
15.   Resistivity is the basics  for the d.c resistivity method. Correspondence in resistivity of a sample within a given ranges indicate the presence of such substance.
16.   All soil and rock types have their characteristic resistivity.
17.   Seismic refraction: a direct current resistivity method employed in shallow depth seismology. It is less expensive and ideal for shallow depth like ground water, dams  explorations etc
18.   Radiometric method: is a gamma ray spectroscopy used as geological mapping tool.
19.   The slope of T and X determine the velocity of the seismic wave in seismic refraction.
20.    Radiocarbon dating: is a method for determining the age of substance containing organic matter using the properties of carbon -14.
21.   Both seismic method and D.C resistivity method can be used to determine the depth of rocks.
22.   The basics of radiometry is concentration of radioelement in rocks.
23.   All rocks and sol type have unique amount of radioelement.
24.   Half life is the unique property of all radioelement.
25.   The three element found in rocks are potassium, uranium and thorium
26.   The gamma ray emitted each radioelement have its unique energy.
27.   Air borne gamma ray spectroscopy can be used for geological mapping
28.   The concentration of gamma rays are measured using crystals that scintillate at contact with gamma radiation.
29.   Low-flying aircraft with elevation of 40-150m above ground level can be used in radiometry.
30.   The law of radioactive disintegration covering radiometry are
31.   Gamma ray can move several centimeter through rocks and several hundredths of meters through air
32.   Gamma rays originates as a result of natural decay of radioactive elements.
33.   Photomultiplier convert scintillation to voltage proportional to the energy of of the gamma ray.
34.   Gravity method is based on the mutual attraction between experienced between two mass as explained by newton’s universal gravitational law.
35.   Failing body ,pendulum nd mass on spring measurement are method employed in gravity method
36.   Rocks , soil types and all substance ave their characteristic density
37.   Density of substance is the basic in gravity method
38.   The equation for the determination of the age of rocks is t=ln(D/N) 1/H
39.   Magnetic field method measures magnetic field susceptibility.
40.   Thermal method measures the variation of geothermal temperature.
41.   Tidal effect occur due to presence of heavenly bodies like sun, moon, etc
42.   The equation for apparent resistivity is given by equation.
43.   The 1st law of radioactive decay “ atoms of radioactive element are constantly disntgrating into radioactive product with the emission of alpa, beta or gamma radiatons.”
44.    The 2nd law of radioactive decay “the number of atoms decaying  per second is proportional to the number of atoms presents”
45.   The 3rd law of radioactive decay “ particle decay  are independent of any phenomena like temperature and pressure”
46.   The depth in seismic reflection is given by equation
47.   The depth in seismic refraction is given by equation
48.   Schulemberger equation  is given by equation
49.   Gravity station is a point where gravimeter is installed to calculate value of gravity
50.   Seismograph an instrument that measure and records earth quakes such as force and duration

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