81. The seismic velocity of a rock is primarily controlled by: A. Temperature B. Density and elasticity C. Resistivity D. Permeability Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B Solution: Seismic velocity depends on the density and elastic moduli (Young�s and bulk modulus) of the material.
82. What does a high-resistivity anomaly usually indicate? A. Wet clay B. Saturated silt C. Compact dry rock D. Peat layer Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: A high-resistivity anomaly often indicates dry, compact, or resistive materials like granite or dense limestone.
83. The tool used to record seismic waves is called: A. Electrometer B. Magnetometer C. Geophone D. Resistivimeter Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: A geophone is an instrument that converts ground motion into voltage, used to detect seismic waves.
84. In seismic methods, what does travel time refer to? A. Time to set up equipment B. Time to process data C. Time for waves to reach a receiver D. Time before seismic shaking begins Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Travel time is the time taken by a seismic wave to travel from the source to the detector.It�s used to calculate depth and velocity.
85. What is the role of the base station in a magnetic survey? A. Collect seismic data B. Provide electric current C. Record daily magnetic variations D. Calibrate seismic velocity Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: In magnetic surveys, a base station records diurnal changes in the Earth's magnetic field for correction of mobile station data.
86. Which array provides better depth penetration in resistivity surveys? A. Wenner array B. Dipole-dipole array C. Schlumberger array D. Pole-pole array Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: Schlumberger arrays offer greater depth penetration due to wider spacing between current electrodes.
87. What is the purpose of a Bouguer correction in gravity surveys? A. To reduce atmospheric errors B. To account for elevation differences C. To convert magnetic data to gravity data D. To measure water content Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B Solution: Bouguer correction adjusts gravity readings to a common elevation datum, removing effects of height.
88. A gravimeter measures: A. Changes in electrical resistance B. Magnetic field intensity C. Acceleration due to gravity D. Wave travel time Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option C Solution: A gravimeter is a sensitive instrument that measures small variations in gravitational acceleration.
89. What is the typical unit of magnetic field strength used in magnetic surveys? A. Tesla B. Ampere C. Gauss D. Newton Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option A Solution: Magnetic field strength is often expressed in nanoTesla (nT) or Tesla.1 Tesla = 10,000 Gauss.
90. What does a resistivity sounding curve show? A. Water table fluctuation B. Variation of resistivity with depth C. Surface temperature changes D. Soil color variation Answer & Solution Discuss in Board Save for Later Answer & Solution Answer: Option B Solution: A resistivity sounding curve plots apparent resistivity vs electrode spacing, used to interpret subsurface layering.
