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DAY 3 - APPLIED GEOLOGY > Week 2 > Flashcards

Week 2 Flashcards

1
Q

It is a point at which three lithospheric plates meet.

A

Triple Junction

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2
Q

Who invented the system of longitude and latitude and made a map of the spherical world?

A

Eratosthenes of Cyrene

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3
Q

This theorem is described to be the most general displacement of a rigid body with a fixed point is equivalent to a rotation about an axis through that fixed point.

A

Euler’s Fixed Point Theorem

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4
Q

What process allows rocks to record the Earth’s past magnetic field?

A. Sedimentation
B. Magnetization
C. Paleomagnetism
D. Crystallization

A

C. Paleomagnetism

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5
Q

What is the main function of a fluxgate magnetometer in magnetic surveying?

A. Detecting seismic waves
B. Measuring magnetic anomalies
C. Inducing magnetization
D. Elevation correction

A

B. Measuring magnetic anomalies

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6
Q

What law states, “for relatively small deformations of an object, the displacement or size of the deformation is directly proportional to the deforming force or load”?

A

Hooke’s Law

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7
Q

What is the primary characteristic of a dipole field in Earth’s magnetic field?

A. Complex structure
B. Multi-polarity
C. Simple, largely dipolar
D. Chaotic orientation

A

C. Simple, largely dipolar

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8
Q

It is aligned at 11.5 ° to the earth’s geographic north-south axis (spin axis).

A. Geomagnetic North
B. Best-fitting dipole
C. Dipole field
D. Geomagnetic South

A

B. Best-fitting dipole

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9
Q

How often is the IGRF updated?

A

5 years

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10
Q

The ratios between the sine of each angle and their corresponding velocity are equal to a constant called?

A

Ray parameter

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11
Q

A mountain in isostatic equilibrium must be compensated by a ______ between the surface and compensation depth.

A

mass deficiency

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12
Q

Which among the following is true about ground magnetic surveys?

A. Covers a relatively small area with 10 to 100 kilometer station spacing
B. Avoid metallic objects and power lines
C. Is cost-effective compared to other magnetic survey methods
D. All of the above

A

B. Avoid metallic objects and power lines

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13
Q

These are zones of charged particles trapped by the Earth’s magnetic field, providing a protective shield against harmful radiation.

A

Van Allen Radiation Belts

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14
Q

This triple junction is always unstable.

A

FFF

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15
Q

If four (4) or more plates meet at one point, the configuration is always ______ and the system will evolve into two (2) or more triple junctions.

A

unstable

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16
Q

Define geoid.

A

Reference surface equivalent to sea level.

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17
Q

What are the Geomagnetic North and Geomagnetic South?

A

Geomagnetic North – 79◦N, 71◦W
Geomagnetic South – 79◦S, 109◦E

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18
Q

What is the IGRF?

A

International Geomagnetic Reference Field (IGRF) – The internationally agreed values of the geomagnetic field.

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19
Q

What are the plates involved in the Galapagos triple junction?

A

Cocos Plate, the Nazca Plate, and the Pacific Plate

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20
Q

Define the term magnetic (dip) poles.

A

The two points on the Earth’s surface at which the magnetic field is vertical and has no horizontal component.

21
Q

Any changes in the solar wind, and hence in the magnetic field, can allow these charged particles
to enter the upper atmosphere, causing:

A

Northern Lights - Aurora Borealis
Southern Lights - Aurora Australis

22
Q

Describe the term Eötvös correction.

A

Correction applied to gravity data taken on moving vehicles.

23
Q

In aeromagnetic surveys, aircrafts can use a fixed “stinger” (aircrafts tail) in order to?

A

Compensate for the aircraft’s magnetic field

24
Q

What is space weather?

A

Space weather involves active processes and interactions between the magnetosphere and solar wind.

25
Q

Differentiate magnetic declination and magnetic inclination.

A

Magnetic inclination - angle between the earth’s surface and the magnetic field lines
Magnetic declination - angle between the magnetic north of the compass and the true north

26
Q

What is the VMM hypothesis?

A

VMM Hypothesis states that magnetic stripes are caused by seafloor spreading. It was proposed by F.J. Vine, D.H. Matthews, and L.W. Morley.

27
Q

What do the black and white magnetic stripes infer?

A

Black Stripe – strong record, normal polarity
White Stripe – low record, reversal occurred

28
Q

What does the Königsberger Ratio mean?

A

It is the proportion of remanent magnetization relative to induced magnetization in natural rocks.

29
Q

What is a magnetosphere?

A

It is the magnetic field that envelops the Earth.

30
Q

What does Absolute Motion mean?

A

The motions of the plates relative to some imaginary fixed point; to calculate hotspot since hotspot is fixed.

31
Q

What are the coordinates of the present North and South Magnetic Poles?

A

North Magnetic Pole (present) – 76◦N, 101◦W
South Magnetic Pole (present) – 66◦S, 141◦E

32
Q

Differentiate magnetosheath and magnetopause.

A

Magnetosheath – turbulent zone w/n the bow shock
Magnetopause – inner boundary of magnetosheath

33
Q

What is Airy’s Hypothesis?

A

When isostatic equilibrium is achieved by mountains having deep roots and ocean basins have anti‐roots.

34
Q

Explain Terrain Correction.

A

Correction due to topography – only applied to rugged terrain

35
Q

Define isostasy.

A

The state of balance/equilibrium between the lithosphere and asthenosphere.

36
Q

Assume pc= 2800 kg/m^3, pm= 3100 kg/m^3, D= 30 km. What crustal density p1 is needed to explain the 5km high Tibetan Plateau?

A
37
Q

Discuss the stability of the TTT triple junction. Provide illustration and example.

A
38
Q

Simply explain the difference between dextral and sinistral faults. Give an example that occurred in the country.

A

Dextral - right-lateral (Ex. Marikina Valley Fault System)
Sinistral - left-lateral (Ex. Philippine Fault)

39
Q

What does it mean when a triple junction is always stable? Give examples.

A

When the relative motions of the 3 plates and the azimuth of their boundaries are such that the configuration of the junction does not change with time. Examples: Galapagos, Azores, Afar

40
Q

Expound the configuration and findings in the Mendocino triple junction. Provide the plates involved.

A

Configuration - Unstable (an FFT)
Findings - deformation, high magnitudes
Plates - Juan de Fuca, Pacific, North America

41
Q

Expound the term hotspot volcanism and give an example.

A

It is a place where melt rises from deep in the mantle and formed volcanic islands as the plate moved over. Example: Hawaiian-Emperor seamount chain

42
Q

What does Magnetic Gradiometers measure? Provide examples.

A
  • measures horizontal and vertical magnetic gradients
    1. Ground surveys
    2. Aeromagnetic surveys
    3. Marine surveys
43
Q

Discuss the use of magnetic surveying and provide one (1) instrumentation and data collection technique for magnetic exploration.

A
  • investigates the anomalies of the earth’s magnetic field caused by the magnetic properties of rocks in the subsurface

Instruments/Techniques:

  1. Fluxgate Magnetometer
  2. Proton Magnetometer (Nuclear Precession)
  3. Optically Pumped Magnetometer (Alkali Vapour Magnetometer)
  4. Magnetic Gradiometers
44
Q

Illustrate and discuss Pratt’s Hypothesis.

A

Pratt’s hypothesis states that the density of the lithosphere is not uniform. Isostatic compensation is achieved by a lateral variation of density beneath surface features.

45
Q

Calculate the mass of Earth.

A
46
Q

Show how direct wave, head wave, and reflected wave behave in a ray path illustration.

A
47
Q

Illustrate a model about Airy’s Hypothesis on isostasy.

A
48
Q

Find the Free-Air Correction using the following values:
go = 9.81 m/s2
R = 6371 km
h = 1 m

A
49
Q

Discuss the principles behind the Optically Pumped Magnetometer (Alkali Vapour Magnetometer) and its application in magnetic exploration.

A

Optically pumped magnetometer uses evaporated alkali in a glass cell energized by light, measuring changes in the frequency splitting.

DAY 3 - APPLIED GEOLOGY (1 decks)

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