Why are some areas more prone to tectonic hazards?

Question 1

What is a natural hazard?

Answer 1

. Is a naturally occurring event.
. Threatens human lives.
. Causes damage to property.
. Can be tectonic or climate-related.

Question 2

Causes of tectonic hazards

Answer 2

Caused by plate movements - when continental crusts and oceanic floors move

Question 3

Examples of tectonic hazards

Answer 3

. Earthquake
. Volcanic eruptions
. Tsunamis

Question 4

Distribution of tectonic hazards

Answer 4

Mainly concentrated near the coastlines of the Pacific Ocean

Question 5

Cause of climate-related hazards

Answer 5

Severe and extreme weather and climate conditions

Question 6

Examples of climate-related hazards

Answer 6

. Floods
. Storms
. Droughts

Question 7

Distribution of climate-related hazards

Answer 7

. More widely distributed.
. Found in the Pacific Ocean, Atlantic Ocean, Indian Ocean, North America, South America, Africa, Australia and Asian regions.

Question 8

What is the internal structure of the Earth?

Answer 8

The main layers of the Earth are the core, mantle and crust.

Question 9

Crust

Answer 9

. Solid rock (basalt and granite rocks)
. Thickness ranges from a few kilometers to more than 70 km
. Consists of continental crust (C-C) and oceanic crust (O-C)

Question 10

Mantle

Answer 10

. Mostly solid rock
. About 2,900 km thick
. Temperature between 800°C and 3,000°C
. Two layers: uppermost mantle and lower mantle
. Uppermost mantle + overlying crust = lithosphere (rigid and brittle)
. Lower mantle (semi-molten) forms the asthenosphere

Question 11

Core

Answer 11

. Mostly iron and nickel
. About 3,500 km thick
. Temperature between 3,500°C and 5,000°C
. Solid inner core and extremely hot
. Liquid outer core and very hot

Question 12

What is a tectonic plate?

Answer 12

. The lithosphere (uppermost mantle and overlying crust) is broken into a number of large and small rigid tectonic plates that move in the relation to one another.
. Tectonic plates can be made up of either oceanic crust, continental crust or a combination of both.

Question 13

Types of crust

Answer 13

Oceanic and Continental

Question 14

Location and distribution of oceanic crust

Answer 14

. Beneath the Earth’s ocean.
. Occupies 67% of the Earth’s surface.

Question 15

Characteristics of oceanic crust

Answer 15

. Rock type: Mostly basalt (heavy and dense).
. Thickness: 5 km - 8 km
. Age of Rock: < 200 million years old (young rock).
. Does not get deformed but gets melted and destroyed.

Question 16

Location and Distribution of continental plates

Answer 16

. Beneath the Earth’s continental land masses and under shallow seas close to continents.
. Occupies 33% of the Earth’s surface.

Question 17

Characteristics of continental crust

Answer 17

. Rock type: Granite (lighter and coarser-grained).
. Thickness: 35 km - 70 km.
. Age of Rock: up to 4 billion years old (old rock).
. Does not melt of get destroyed but gets deformed (e.g., folded, faulted).

Question 18

Why do tectonic plates move?

Answer 18

1. Plates move due to convections currents and slab-pull force.
2. The core heats up the magma in the mantle, causing it to expand, rise and spread outwards beneath the plates. As it spreads out, it pulls the plates along.
3. Magma cools slightly, sinks and pulls the plates along.
4. Slab-pull force occurs when a denser oceanic plate subducts underneath a less dense continental or oceanic plate, driving the downward motion of the convection current.
5. As magma descends towards the core, it heats up and the process repeats itself in a convection current.

Question 19

Convergent Plate Boundary Movement

Answer 19

Plates are moving towards each other

Question 20

Divergent Plate Boundary Movement

Answer 20

Plates moving away from each other

Question 21

Transform Plate Boundary Movement

Answer 21

Plates are sliding past each other

Question 22

Process of divergent: Continental - continental plate boundary

Answer 22

1. When 2 continental plates diverge,
2. tensional force causes fault lines to form.
3. Faulting occurs when one portion of the crust slides down along the fault lines
4. to form a linear depression called a rift valley.
5. The surrounding landforms that remain standing are block mountains.

Question 23

Process of Divergent: Oceanic - oceanic

Answer 23

1. When 2 oceanic plates diverge,
2. sea floor spreading occurs when magma rises from the mantle through the gaps
3. and cools and solidifies to form new sea floor.
4. A mid-oceanic ridge forms overtime,
5. with the younger rocks closer to the plate boundary and older rocks further away.

Question 24

Process of Convergent: Continental - oceanic/ Continental - continental

Answer 24

1. When 2 continental plates or 1 oceanic plate and 1 continental plate converge,
2. the buoyant continental crust resist subduction and folding occurs.
3. Compressional force causes the continental crust to collide, buckle and uplift
4. to form fold mountains with synclines and anticlines.

Question 25

Process of Convergent: O-O/ O-C

Answer 25

1. When 2 oceanic plates or 1 oceanic plate and 1 continental plate converge,
2. subduction occurs when the denser plate subduct under the less dense plate.
3. A steep linear depression in the sea floor, called the oceanic trench forms at the subduction zone.
4. The subducted plate melts to form magma which rises through fractures in the earth crust, and erupt successively to form stratovolcanoes.

Question 26

Process of Convergent: O-C

Answer 26

1. When 1 oceanic and 1 continental plate converge,
2. the denser oceanic plate subducts under the less dense continental plate.
3. An oceanic trench forms at the subduction zone.
4. Compressional force causes the buoyant continental crust to buckle to form fold mountains.
5. The subducted plate melts to form magma, which rises through fractures in the earth crust, and erupt successively to form stratovolcanoes.