Geophysics

Question 1

an angle in which the angle of incidence that provides the angle of refraction of 90 degrees

Answer 1

Critical Angle

Question 2

point at which the refracted ray overtakes the direct ray

Answer 2

Crossover Distance/Crossover Point

Question 3

a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment

Answer 3

Geophysics

Question 4

is detected when a survey encounters some geometric perturbation in the distribution of a particular physical property in the rocks

Answer 4

Geophysical Anomaly

Question 5

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

Answer 5

Gravity Anomaly

Question 6

objective of the survey; due to the causative body or target body

Answer 6

Signal

Question 7

anything else measured but which may not contain useful information

Answer 7

Noise

Question 8

remedy for

a. Natural Noise
b. Artificial Noise
c. Geologic Noise

Answer 8

a. discontinue measurements
b. stay away from the source
c. mathematical corrections

Question 9

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

Answer 9

a. Ground
b. Airborne
c. Marine
d. Borehole

Question 10

degree to which a substance may be magnetized

Answer 10

Magnetic Susceptibility

Question 11

deformation that vanish upon removal of the stresses

Answer 11

Elasticity

Question 12

ability of a material to conduct electrical current

Answer 12

Conductivity

Question 13

which is a rock unit of different density from its surroundings

Answer 13

Causative Body

Question 14

spring balances carrying a constant mass that directly measure small diferences in the strength of gravity

Answer 14

Gravimeter or Gravity Meter

Question 15

are polarized shear waves with a particle motion parallel to the free surface and perpendicular to the direction of wave propagation

Answer 15

Love Waves

Question 16

propagate along a free surface or along the boundary between two dissimilar solid media

Answer 16

Rayleigh waves

Question 17

propagate by compressional or dilational uniaxial strains in the direction of wave travel

Answer 17

P Waves

Question 18

can propagate along the boundary of the solid

Answer 18

Surface wave

Question 19

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

Answer 19

Seismic Reflection Method

Question 20

propagate by a pure shear strain in a direction perpendicular to the direction of wave travel

Answer 20

S Wave

Question 21

the later time of arrival of the reflected rays at receivers offset from the source for a horizontal reflector

Answer 21

Normal Moveout

Question 22

a weighted average across n-layers that factors out the differences in travel time spent in layers of differing velocity

Answer 22

Root Mean Square

Question 23

to determine the gross resistivity features of a prospect and its surrounding region

Answer 23

Mapping/Profiling/Traversing

Question 24

to determine the vertical resistivity structure at a set of stations

Answer 24

Vertical Electrical Sounding

Question 25

electrodes are uniformly spaced

Answer 25

Wenner Spread

Question 26

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

Answer 26

Dipole-dipole Spread

Question 27

current electrodes are spaced much farther than the potential electrodes

Answer 27

Schlumberger Spread