Plate Tectonics

Question 1

The Earth’s lithosphere consists of what layers?

Answer 1

The crust; the upper part of the mantle (rigid mantle).

Question 2

What are the three (3) various kinds of rocks consisting the crust?

Answer 2

Sedimentary; metamorphic; igneous

Question 3

What is the average density of the crust? What is the thickness of the crust?

Answer 3

2.8 g/cm^3

5 to 5 km

Question 4

The crust is thickest in _____ and thinnest along the _____

Answer 4

Mountains; ocean floor

Question 5

There are two (2) kinds of crust: the thicker but less dense _____; and the thinner but denser _____.

Answer 5

Continental crust; Oceanic crust

Question 6

According to the plate tectonics model, the entire lithosphere of the Earth is broken into numerous segments called what?

Answer 6

Plates

Question 7

Geologists consider seven (7) large plates, these are?

Answer 7

North American Plate; South American Plate; Eurasian Plate; African Plate; Indo-Australian Plate; Pacific Plate; and Antarctic Plate.

Question 8

The movement of plates are described to be slow but constant. Such movement is called? The theory of moving lithospheric plates?

Answer 8

Tectonics. Plate tectonics.

Question 9

An earthquake releases three (3) types of seismic waves. These are?

Answer 9

Primary (P-waves); Secondary (S-waves); Long surface waves (L-waves)

Question 10

Among the three (3) seismic waves, which two travel into the Earth’s interior? Which one travels on the surface?

Answer 10

Primary (P-waves) and Secondary (S-waves) travel into the Earth’s interior. Long surface waves (L-waves) travel on the Earth’s surface.

Question 11

How is the distance of the recording instrument to the earthquake’s focus related to the difference in the arrival times of the first P-wave and the first S-wave?

Answer 11

The farther the distance, the greater the difference in arrival times.

Question 12

What does the difference in the arrival times tell us and does not tell us?

Answer 12

It estimates the distance of the earthquake’s focus from the seismic recording station. It, however, doesn’t tell us the direction.

Question 13

This method allows us to determine where the epicenter of the earthquake is located through drawing circles around seismic stations whose radii are scaled to the distance of the station from the earthquake. What method is this? How many seismic recording stations are required?

Answer 13

Triangulation Method. Three (3) seismic recording stations.

Question 14

Geologic events and deformations—such as earthquakes and formation of mountains, volcanoes and trenches—occur in plate boundaries. These are classified into three (3) distinct types according to the type of movement they exhibit. What are these three (3) types?

Answer 14

Divergent plate boundary; Convergent plate boundary; Transform fault boundary.

Question 15

This type of plate boundary is exhibited by how plates move apart each other—creating a zone of tension.

Answer 15

Divergent plate boundary.

Question 16

This type of plate boundary is exhibited by the sliding or grinding of plates past each other. What is this? What fault bounded by the North American and Pacific plates best exemplifies this?

Answer 16

Transform fault boundary. San Andreas fault.

Question 17

In a convergent plate boundary situation, which one sinks, the continental or the oceanic crust? Why?

Answer 17

The oceanic crust. Owing to it being more dense/denser than the continental crust.

Question 18

Collision of two plates—an oceanic and a continental—gives rise to the formation of what geological occurrence near the edge of a continental leading plate?

Answer 18

Volcanic arc(s).

Question 19

This process is described as the bending of the crust towards the mantle.

Answer 19

Subduction process.

Question 20

As the denser crust sinks toward the mantle, the sunk crust melts—owing to the mantle being hotter—which forms what substance which rises to the crust and causes volcanic activities after addition of volatile material such as water?

Answer 20

Magma.

Question 21

With a oceanic-continental convergence situation, this important geological feature occurs or is formed? They are the deepest part of the ocean.

Answer 21

Trench, also known as submarine valleys.

Question 22

Aside other geological features occurring or forming owing to oceanic-continental convergence, this is also a subsequent effect of the continuous grinding of plates against each other which releases huge amounts of energy. What is it?

Answer 22

Earthquakes.

Question 23

Such geological occurrence which releases energy after continuous plate grinding is classified according to its foci’ varying depths. What are these, according to the depth: 60km deep - _____; 60km to 300km deep - _____; and 300km to 700km deep - _____.

Answer 23

Shallow earthquakes; intermediate earthquakes; deep earthquakes

Question 24

It is a Japanese term for “harbor wave;” it is a series of ocean waves with very long wavelengths—typically hundreds of kilometers—caused by large-scale disturbances of the ocean or underwater earthquakes.

Answer 24

Tsunami.

Question 25

It is a chain of volcanoes position in an arc shape. It occurs as the leading edge of the sunk plate eventually reaches the mantle, causing it to melt and turn into magma which, in turn, rises to the surface creating this feature parallel to the trench.

Answer 25

Volcanic island arc.

Question 26

This convergence is described as the collision of two oceanic plates—with one of the plates sinking under the other. This also is what many parts of the Philippines arise from.

Answer 26

Oceanic-oceanic convergence.

Question 27

A majority of the islands in the Philippine archipelago are considered as part of this belt. These islands were formed 65 million years ago at the southern edge of the Philippine Sea Plate and are considered as part of island arcs.

Answer 27

Philippine Mobile Belt.

Question 28

Aside from the belt, some other parts of the Philippines—such as Palawan, Mindoro, and the Zamboanga Peninsula—are all highland sections of what block of the Eurasian Plate? This block collided with the belt from where majority of the Philippine islands are which explains the presence of trenches such as the Manila-Negros-Cotabato Trench System, and the Sulu Trench.

Answer 28

Sundaland block.