Geophysics Flashcards
an angle in which the angle of incidence that provides the angle of refraction of 90 degrees
Critical Angle
point at which the refracted ray overtakes the direct ray
Crossover Distance/Crossover Point
a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment
Geophysics
is detected when a survey encounters some geometric perturbation in the distribution of a particular physical property in the rocks
Geophysical Anomaly
arise due to laterla perturbations in rock, density, magnetic ones are caused by lateral changes in rock magnetization, and seismic anomalies indicate variations in acoustic impedance
Gravity Anomaly
objective of the survey; due to the causative body or target body
Signal
anything else measured but which may not contain useful information
Noise
remedy for
a. Natural Noise
b. Artificial Noise
c. Geologic Noise
a. discontinue measurements
b. stay away from the source
c. mathematical corrections
a. applied for flat or gently undulating terrain
b. for large or heavily forested areas
c. for offshore investigations
d. records one or more physical properties as a function of depth
a. Ground
b. Airborne
c. Marine
d. Borehole
degree to which a substance may be magnetized
Magnetic Susceptibility
deformation that vanish upon removal of the stresses
Elasticity
ability of a material to conduct electrical current
Conductivity
which is a rock unit of different density from its surroundings
Causative Body
spring balances carrying a constant mass that directly measure small diferences in the strength of gravity
Gravimeter or Gravity Meter
are polarized shear waves with a particle motion parallel to the free surface and perpendicular to the direction of wave propagation
Love Waves
propagate along a free surface or along the boundary between two dissimilar solid media
Rayleigh waves
propagate by compressional or dilational uniaxial strains in the direction of wave travel
P Waves
can propagate along the boundary of the solid
Surface wave
a dynamic geophysical technique of generating sound wave at a source and recording the time it takes in which seismic energy to return and be recorded
Seismic Reflection Method
propagate by a pure shear strain in a direction perpendicular to the direction of wave travel
S Wave
the later time of arrival of the reflected rays at receivers offset from the source for a horizontal reflector
Normal Moveout
a weighted average across n-layers that factors out the differences in travel time spent in layers of differing velocity
Root Mean Square
to determine the gross resistivity features of a prospect and its surrounding region
Mapping/Profiling/Traversing
to determine the vertical resistivity structure at a set of stations
Vertical Electrical Sounding
electrodes are uniformly spaced
Wenner Spread
a denotes constant separation between the electrodes and the distance between B and M can be increased to be an integral multiple of n and a
Dipole-dipole Spread
current electrodes are spaced much farther than the potential electrodes
Schlumberger Spread
