Week2 D3

Question 1

The theory states that new lithosphere is formed at ocean ridges due to the uplift of mantle material and moves away until it collides with another plate and subduct. The motion is described to me similar to a conveyor belt.

Answer 1

Plate Tectonics

Question 2

The theory was proposed to explain magnetic anomalies on the sea floor

Answer 2

Seafloor spreading

Question 3

Accretionary plate boundaries where new lithosphere is formed from upwelling mantle

Answer 3

Ocean Ridge

Question 4

Average rate of production of oceanic lithosphere

Answer 4

3.5 km^2/yr

Question 5

A seismic region that descends beneath a continental margin or an island arc, with a deep-sea trench serving as its visible manifestation on the surface.

Answer 5

Benioff Zone

Question 6

Most common type of tranform fault

Answer 6

Ridge-Ridge

Question 7

This concept is used to describe motions on the surface on the sphere

Answer 7

Euler’s ‘fixed-point’ theorem

Question 8

This law describes the connection between the trajectory of a light ray as it traverses the boundary or interface between two adjacent substances and the refractive index of each substance involved.

Answer 8

Snell’s Law

Question 9

measuring the precise position of sites on the Earth’s surface from sources in space, such as radio-wave sources and satellite tracking

Answer 9

Space Geodesy

Question 10

Is a type of force that pulls the body apart

Answer 10

Tensional

Question 11

two opposite forces that act upon the same object, but not along the same line

Answer 11

Shear Forces

Question 12

External forces that tend to compress

Answer 12

Compresisonal

Question 13

Types of deformation

Answer 13

Plastic

Question 14

Formula for Young’s Modulus

Answer 14

Tensile stress/Tensile Strain

Question 15

Formula for Shear Modulus

Answer 15

Shear Stress/Shear Strain

Question 16

Rigid body deformation is categorized into

Answer 16

Translation and Rotation

Question 17

What are the basic premises in plate tectonics

Answer 17

> Lithosphere is a rigid and strong substancer resting on a weaker plastic region called asthenosphere
Lithosphere is broken into several segments known as plates

Question 18

Four types of seismic boundaries based on epicenter distributions and geologic characteristics

Answer 18

Ocean Ridges, Subduction Zones, Transform Faults and Collisional Zones

Question 19

Seven Major Plates

Answer 19

Eurasion, Antarctic, N. American, S. American, Pacific, African, and Australian Plates

Question 20

Examples of Intermediate plates, give 3

Answer 20

Philippine, Arabian, Nasca, Cocos, Carribean, Scotia Plates

Question 21

Examples of Small plates, give 3

Answer 21

Turkish-Aegean, Adriatic, Arabian, Iran Plates

Question 22

Two Types of continental margins

Answer 22

Active continental margins and Passive continental Margins

Question 23

Active vs Passive continental margins

Answer 23

Active Continental Margin: subduction zone or a transform fault coincides with continent-ocean interface.
Passive Continental Margin: along edges of basins where little to no tectonic activity is seen

Question 24

Difference betwwen fast and slow spreading ridges in terms of axial topography

Answer 24

Fast Spreading ridges: low relief; some intances of topographic highs
Slow Spreading ridges: deep axial valley, flanking mountains

Question 25

What are transform faults

Answer 25

plate boundaries where they slide past each other and plate surface is more or less conserved

Question 26

Three types of Transform faults

Answer 26

Ridge-Ridge, Trench-Trench, Ridge-Trench Faults

Question 27

The formula for getting the relative velocy (v) between two plates

Answer 27

v = ωR sin θ [ ω = angular velocity, R = earth’s radius, θ is the angular distance between the rotation pole P and a certain point]

Question 28

Give the chemical equation for the conversion of microcline to kaolinite

Answer 28

2 KAlSi3O8 + 9H2O + 2H <=> Al2Si2O5(OH)4 +2K + 4H4SiO4

Question 29

What are the mechanism that drives plate movement

Answer 29

Slab pull and Ridge Push

Question 30

Non rigid body deformation is categorized into

Answer 30

Distorsion, Dilation

Question 31

What is Young’s modulus

Answer 31

The property of a material pertaining to how easily it can strech and deform.

Question 32

What is the definition of Shear Modulus

Answer 32

Measures the resistance of a material to change shape, usually applied for shear stress

Question 33

What is Poisson’s Ratio

Answer 33

the ratio between the strain in width vs length; pertains to the overall strain of a material

Question 34

What is the Bulk Modulus or Incompressibility

Answer 34

a measure of a material’s resistance to compression

Question 35

What does INSAR stand for

Answer 35

Interferometric Synthetic Aperture Radar

Question 36

Why doesnt the earth grow despite the production of new crust at ocean ridges

Answer 36

As new crust is produced from the upwelling of magma at oceanic ridges, old oceanic crust is destroyed as they subduct to the mantle.

Question 37

Illustrate the geometry of RRR triple junction

Answer 37

Illustration at physical copy

Question 38

Illustrate the geometry of TTT triple junction

Answer 38

Illustration at physical copy

Question 39

Illustrate the geometry of TTF triple junction

Answer 39

Illustration at physical copy

Question 40

Illustrate the geometry of FFR triple junction

Answer 40

Illustration at physical copy

Question 41

Illustrate the geometry of FFT triple junction

Answer 41

Illustration at physical copy

Question 42

Illustrate the geometry of RTF triple junction

Answer 42

Illustration at physical copy

Question 43

Illustrate the six types of transform fault

Answer 43

A. Ridge-Ridge
B and C. Ridge-Trench
D, E and F. Trench-Trench

Question 44

Breifly explain and Illustrate the Wilson Cycle

Answer 44

The repetitive process of ocean basins opening and closing is attributed to the Earth’s plate movements. The Wilson cycle commences with the emergence of a magma plume and the subsequent thinning of the overlying crust. As extensional tectonic forces persistently thin the crust, an ocean basin takes shape, and sediments gather along its borders. Eventually, subduction begins at one of the ocean basin’s edges, leading to the closure of the basin.

Question 45

What would be the relative velocity of Plate B, based from an observer standing on Plate C?

Answer 45

Illustration at physical copy

Question 46

How high does a 70km-thick crust stick out above the mantle

Answer 46

Illustration at physical copy

Question 47

Assume the mechanism for co-seismic defomation at the PFZ is simple shear. A certain region affected by shearing extends for 80 km on either side of the fault and the average displacement parallel to the fault is 6 m. Calculate the shear strain

Answer 47

Illustration at physical copy

Question 48

Why is plate tectonics an important theory in Geology?

Answer 48

The concept of plate tectonics is a unifying theory that explains much of earth’s processes.

Question 49

Can tranform faults produce new crust, if so then how?

Answer 49

Oceanic transform fault boundary are “leaky” where magma escapes from such boundaries producing slivers of lithosphere

Question 50

Why is it that hypocenters are only found until 660 km depth?

Answer 50

Beyond the 660 km dpeth lies the asthenosphere. Since the layer is plastic in nature, brittle deformation cannot happen since its response would be ductile. This earthquakes does not occur beyond these depths.