Universe Chapter -2-

Question 1

How many Years is the Earth? How much is it’s diameter?

Answer 1

4.56 million years ago, radius= 6400 km

Question 2

Three layers of earth:

Answer 2

Core (17%)
Mantle (81%)
Crest (2%)

Question 3

Three important discontinuities are:

Answer 3

MOHO: between earth’s crust and mantle
GUTENBERG: between mantle and core
LEHMANN: between inner and outer core

Question 4

What’s outside the earth and what’s inside it?

Answer 4

Outside it is the atmosphere and cooled water that condensed in oceans, Inside are rocks that cooled down and settled into more organized layers

Question 5

who’s much denser oceanic crust or continental crust?

Answer 5

Oceanic crust is much denser

Question 6

composition of each:
Crust
UPPER & LOWER MANTLE
OUTER & INNER CORE

Answer 6

Crust composed of: Basalt and granites
Upper & Lower mantle: Fe+ and Mg
Outer & Inner core: Iron Alloy

Question 7

Lithosphere

Answer 7

composed of rigid plates that slide due to convection movement on the Asthenosphere (crust and superficial part of upper mantle)

Question 8

Asthenosphere

Answer 8

most plastic section of upper mantle, it’s a hot layer (1500 degree C)

Question 9

What are Plate Tectonics?

Answer 9

Deformations in the lithosphere are related to convection movements in the asthenosphere

Question 10

What are the THREE types of Boundaries?

Answer 10

Convergent (two plates come close)
Divergent (two plates move apart)
Transforming (two plates move laterally against each other)

Question 11

What is the reason behind Earthquakes?

Answer 11

sudden movement of large blocks of earth’s crust
When earthquake occurs rocks vibrate seismic waves
Earthquakes are mainly located on the borders of lithospheric plates but some may occur inside

Question 12

At what point do earthquakes occur ?

Answer 12

Focus point

Question 13

TYPES OF SEISMIC WAVES

Answer 13

Body waves (P WAVE - S WAVE)
Surface waves (L WAVE)

Question 14

What device is used to record seismic waves?

Answer 14

Seismograph, graph obtained is seismogram

Question 15

List the TWO scales used to evaluate an earthquake

Answer 15

RITCHER SCALE (expressed magnitude, quantity of energy)
MERCALLI SCALE (indicates intensity of an earthquake)

Question 16

TYPES OF EARTHQUAKES

Answer 16

• Superficial (0-70 km) ; located within convergent and divergent
• Intermediate (70-300 km); within convergent
• Deep (300-700 km); extremely within convergent

Question 17

What is the cause of Tsunami

Answer 17

Underwater movement related to an earthquake, a volcanic eruption or a landside

Question 18

Volcanoes

Answer 18

Volcanoes aren't randomly distributed, occur at plate boundaries but within plates (intraplate volcanism such as hotspot volcanoes) 
Hotspot Volcanism (intraplate): am oceanic plate

Question 19

What are some types of Rocks?

Answer 19

1- Eruptive or magmatic rocks : -Volcanic (extrusive)
- Plutonic (intrusive)
2- Sedimentary: result from precipitation of elements or accumulation of debris or erosion of surface rocks
3- Metamorphic: Transformation of other TWO types under effect of increase in pressure & temperature

Question 20

What causes deformation of rocks?

Answer 20

Tension, Compression, Sheer.

Folds are produced by compression