Q: Answer

(B) To detect and map subsurface geological structures Explanation: Magnetic methods in geophysics are primarily used to detect and map subsurface geological structures by measuring variations in the Earth's magnetic field caused by different rock types and mineral content.

Q: Answer

(B) Magnetometer Explanation: A magnetometer is the instrument commonly used in geophysical surveys to measure the Earth's magnetic field and detect magnetic anomalies.

Q: Answer

(B) Faster data collection over large areas Explanation: The primary advantage of aeromagnetic surveys is their ability to collect data quickly over large areas, making them efficient for regional-scale geological mapping.

Q: Answer

(C) Mid-ocean ridges Explanation: Magnetic anomalies detected in marine environments are often associated with mid-ocean ridges, where new oceanic crust is formed and records the Earth's magnetic field.

Q: Answer

(C) Mapping iron ore deposits Explanation: Magnetic surveys are commonly used in mineral exploration to map iron ore deposits due to the strong magnetic properties of iron minerals.

Q: Answer

(B) Magnetometer Explanation: A magnetometer is the instrument used to measure the magnetic properties of rocks in paleomagnetic studies. It can detect the strength and direction of magnetic fields.

Q: Answer

(B) The degree to which a material can be magnetized Explanation: Magnetic susceptibility is a measure of how easily a material can be magnetized by an external magnetic field, indicating the concentration of magnetic minerals within the material.

Q: Answer

(B) Using a base station magnetometer Explanation: A base station magnetometer is used to monitor and record diurnal variations in the Earth's magnetic field, allowing for corrections to be applied to the survey data to account for these natural fluctuations.

Question 1

Answer

Accepted Answer

(B) To detect and map subsurface geological structures
Explanation: Magnetic methods in geophysics are primarily used to detect and map subsurface geological structures by measuring variations in the Earth's magnetic field caused by different rock types and mineral content.

Question 2

Answer

Accepted Answer

(B) Magnetometer
Explanation: A magnetometer is the instrument commonly used in geophysical surveys to measure the Earth's magnetic field and detect magnetic anomalies.

Question 3

Answer

Accepted Answer

(B) Faster data collection over large areas
Explanation: The primary advantage of aeromagnetic surveys is their ability to collect data quickly over large areas, making them efficient for regional-scale geological mapping.

Question 4

Answer

Accepted Answer

(B) The temperature at which magnetic minerals lose their magnetism
Explanation: The Curie temperature is the temperature at which magnetic minerals lose their permanent magnetism, becoming paramagnetic.

Question 5

Answer

Accepted Answer

(C) Mid-ocean ridges
Explanation: Magnetic anomalies detected in marine environments are often associated with mid-ocean ridges, where new oceanic crust is formed and records the Earth's magnetic field.

Question 6

Answer

Accepted Answer

(C) Mapping iron ore deposits
Explanation: Magnetic surveys are commonly used in mineral exploration to map iron ore deposits due to the strong magnetic properties of iron minerals.

Question 7

Answer

Accepted Answer

(B) The difference between the measured magnetic field and the theoretical magnetic field
Explanation: The total field anomaly refers to the difference between the measured magnetic field and the theoretical magnetic field, indicating variations caused by subsurface structures.

Question 8

Answer

Accepted Answer

(B) Magnetometer
Explanation: A magnetometer is the instrument used to measure the magnetic properties of rocks in paleomagnetic studies. It can detect the strength and direction of magnetic fields.

Question 9

Answer

Accepted Answer

(B) The degree to which a material can be magnetized
Explanation: Magnetic susceptibility is a measure of how easily a material can be magnetized by an external magnetic field, indicating the concentration of magnetic minerals within the material.

Question 10

Answer

Accepted Answer

(B) Using a base station magnetometer
Explanation: A base station magnetometer is used to monitor and record diurnal variations in the Earth's magnetic field, allowing for corrections to be applied to the survey data to account for these natural fluctuations.

Question 11

Answer

Accepted Answer

(B) To map variations in the Earth's magnetic field at the surface
Explanation: The primary objective of a ground magnetic survey is to map variations in the Earth's magnetic field at the surface, which can reveal subsurface geological structures and mineral deposits.

Question 12

Answer

Accepted Answer

(C) The combined strength of all magnetic field components
Explanation: The total magnetic field intensity is the combined strength of all components of the Earth's magnetic field, including vertical and horizontal elements, measured at a specific location.

Question 13

Answer

Accepted Answer

(C) Accurate measurement of weak magnetic fields
Explanation: Fluxgate magnetometers are highly sensitive instruments capable of accurately measuring weak magnetic fields, making them ideal for detailed magnetic surveys.

Question 14

Answer

Accepted Answer

(B) A fault filled with non-magnetic sediments
Explanation: A fault filled with non-magnetic sediments can create a negative magnetic anomaly because the sediments do not contribute to the magnetic field, resulting in a weaker magnetic signal compared to the surrounding rocks.

Question 15

Answer

Accepted Answer

(C) It provides the angle between magnetic north and true north
Explanation: Magnetic declination is the angle between magnetic north and true north at a specific location, which is important for accurately interpreting magnetic survey data.

Question 16

Answer

Accepted Answer

(B) By detecting buried waste and contamination
Explanation: Magnetic methods can be used in environmental studies to detect buried waste and contamination, as certain materials and pollutants may create distinctive magnetic anomalies that can be mapped and analysed.

Question 17

Answer

Accepted Answer

(D) Isodynamic line
Explanation: An Isodynamic line is a line on a magnetic map that connects points of equal magnetic intensity, helping to visualize the distribution of magnetic anomalies.

Question 18

Answer

Accepted Answer

(B) To measure magnetic field gradients
Explanation: A gradiometer is used in magnetic surveys to measure the gradients of the magnetic field, providing detailed information about the rate of change in magnetic intensity over short distances.

Question 19

Answer

Accepted Answer

(B) A subsurface rock formation with different magnetic properties
Explanation: A magnetic anomaly can be caused by a subsurface rock formation with different magnetic properties, resulting in a variation in the Earth's magnetic field at that location.

Question 20

Answer

Accepted Answer

(B) By detecting changes in magnetic susceptibility
Explanation: Magnetic methods can help identify fault zones by detecting changes in magnetic susceptibility, as faults often juxtapose rocks with different magnetic properties.

Question 21

Answer

Accepted Answer

(C) The total field intensity
Explanation: The primary component of the Earth's magnetic field measured in magnetic surveys is the total field intensity, which includes contributions from both the horizontal and vertical components.

Question 22

Answer

Accepted Answer

(A) To provide a fixed reference point for magnetic measurements
Explanation: A base station in a magnetic survey provides a fixed reference point for magnetic measurements, allowing for the correction of diurnal variations and other temporal changes in the Earth's magnetic field.

Question 23

Answer

Accepted Answer

(D) Basalt
Explanation: Basalt is typically associated with strong magnetic anomalies due to its high iron content, which contributes to its strong magnetic properties.

Question 24

Answer

Accepted Answer

(A) Low cost and rapid data collection
Explanation: The primary advantage of using magnetic surveys in unexplored regions is their low cost and rapid data collection, making them an efficient method for preliminary geological exploration.

Question 25

Answer

Accepted Answer

(B) By detecting buried structures and artifacts
Explanation: Magnetic methods can be used to study ancient human activities by detecting buried structures and artifacts, as these often cause magnetic anomalies that can be mapped and analysed.

Question 26

Answer

Accepted Answer

(B) Isogonic line
Explanation: An Isogonic line is a line on a magnetic map that connects points of equal magnetic declination.

Question 27

Answer

Accepted Answer

(C) Isoclinic line
Explanation: An Isoclinic line is a line on a magnetic map that connects points of equal magnetic dip.

Question 28

Answer

Accepted Answer

(A) Agonic line
Explanation: An Agonic line is a line on a magnetic map that connects points of zero magnetic declination.

Question 29

Answer

Accepted Answer

(D) Aclinic line
Explanation: An Aclinic line is a line on a magnetic map that connects points of zero magnetic dip.

Category: Magnetic Methods

MCQ on Magnetic Methods in Geophysics – Miscellaneous

MCQ on Palaeomagnetism | Unlocking Geological History of the Earth with Paleomagnetic dating

Geomagnetism – Important MCQ

RECENT POSTS

SUBSCRIBE NOW

GENERAL

USEFUL READS

HELPDESK

FOLLOW US