TECTONICS EQ1

Question 1

What is a tectonic hazard?

Answer 1

A tectonic hazard is a natural event caused by the movement of tectonic plates, which can result in disasters such as earthquakes, volcanic eruptions, and tsunamis.

Examples of tectonic hazards include earthquakes, volcanic eruptions, and tsunamis.

Question 2

Where do earthquakes tend to occur?

Answer 2

Earthquakes tend to occur in distinct zones at the edges of tectonic plates, known as plate boundaries.

Intraplate earthquakes can also occur in regions like the Great Rift Valley and Tibet.

Question 3

What influences the magnitude of an earthquake?

Answer 3

The magnitude of an earthquake is influenced by the type of plate boundary.

Examples include convergent and divergent boundaries.

Question 4

What is the distribution of active volcanoes?

Answer 4

Most active volcanoes (about 75%) occur around the ‘Ring of Fire’ surrounding the Pacific Ocean, at convergent and divergent plate boundaries, and at hot spots.

An example of a hot spot is Hawaii.

Question 5

How do tsunamis primarily form?

Answer 5

Tsunamis primarily form along convergent plate boundaries due to undersea earthquakes caused by subduction.

High-risk areas include Japan and Indonesia.

Question 6

What is mantle convection?

Answer 6

Mantle convection is the process by which heat from the Earth’s core causes the movement of semi-solid rock within the asthenosphere, driving tectonic plate movement.

This process creates convection currents.

Question 7

What is slab pull?

Answer 7

Slab pull is the dominant force in tectonic plate movement, occurring when dense oceanic plates sink into the mantle at subduction zones, pulling the rest of the plate with them.

Ridge push is another force, occurring at mid-ocean ridges.

Question 8

What is the significance of paleomagnetism?

Answer 8

Paleomagnetism is the study of changes in the Earth’s magnetic field recorded in rocks, providing evidence for seafloor spreading and plate tectonics.

It shows symmetrical bands of normal and reversed polarity in rocks.

Question 9

What are constructive plate margins?

Answer 9

Constructive plate margins are where two tectonic plates move apart, allowing magma to rise and form new crust, creating mid-ocean ridges or rift valleys.

Examples include the Mid-Atlantic Ridge.

Question 10

What happens at destructive plate margins?

Answer 10

Destructive plate margins occur where two plates collide, leading to subduction, deep ocean trenches, and explosive volcanic activity.

An example is the Andes mountain range.

Question 11

What are the primary hazards of earthquakes?

Answer 11

Primary hazards of earthquakes include:
* Crustal fracturing
* Ground shaking
* Liquefaction
* Landslides
* Tsunamis

Question 12

What are the secondary hazards of volcanoes?

Answer 12

Secondary hazards of volcanoes include:
* Ash falls
* Gas eruptions
* Lahars
* Jökulhlaups

Question 13

What is the definition of a fault?

Answer 13

A fault is a fracture or zone of fractures between two blocks of rock, which can lead to earthquakes.

Faults can vary in size and activity.

Question 14

What is the difference between the hypocenter and epicenter of an earthquake?

Answer 14

The hypocenter is the point within the Earth where an earthquake rupture starts, while the epicenter is the point directly above it on the Earth’s surface.

These terms are crucial for understanding earthquake impacts.

Question 15

What causes the explosive nature of some volcanic eruptions?

Answer 15

The explosive nature of volcanic eruptions is influenced by magma viscosity and gas content, with high-viscosity magma trapping gases and leading to explosive eruptions.

Low-viscosity magma typically results in gentler eruptions.

Question 16

What is the Wadati-Benioff zone?

Answer 16

The Wadati-Benioff zone is a region of seismicity corresponding with the subduction of an oceanic plate beneath another plate, where earthquakes can occur at varying depths.

It is crucial for understanding earthquake depth and magnitude.

Question 17

What is a primary hazard?

Answer 17

A primary hazard is a direct result of a tectonic event, such as ground shaking during an earthquake.

Examples include crustal fracturing and ground shaking for an earthquake, lava flows

Question 18

What is a secondary hazard?

Answer 18

A secondary hazard is an indirect result of a primary hazard, such as landslides triggered by ground shaking.

Question 19

What was the magnitude of the 2004 Indian Ocean earthquake?

Answer 19

The magnitude of the 2004 Indian Ocean earthquake was between 9.1 and 9.3.

This earthquake triggered one of the deadliest tsunamis in history.

Question 20

What were the impacts of the 2004 Indian Ocean tsunami?

Answer 20

The impacts included:
* Over 230,000 deaths
* 1.7 million people displaced
* Economic devastation in fishing and tourism sectors
* Environmental damage including saltwater contamination

Question 21

Fill in the blank: The _______ is the solid inner layer of the Earth composed mostly of iron and nickel.

Answer 21

inner core

Question 22

Fill in the blank: The _______ is the semi-molten part of the upper mantle that allows plate movement.

Answer 22

asthenosphere

Question 23

Which countries were among the hardest hit by the 2004 Indian Ocean tsunami?

Answer 23

Indonesia, Sri Lanka, India, Thailand

These countries faced significant devastation and loss of life due to the tsunami.

Question 24

How many people were killed in the 2004 Indian Ocean tsunami?

Answer 24

More than 230,000 people

The tsunami caused one of the deadliest natural disasters in history.

Question 25

What was the estimated number of people displaced by the 2004 Indian Ocean tsunami?

Answer 25

Around 1.7 million ## Footnote This displacement led to a massive humanitarian crisis.

Question 26

What types of economies were shattered by the 2004 Indian Ocean tsunami?

Answer 26

Economies dependent on fishing and tourism ## Footnote These sectors faced extensive damage and loss of livelihoods.

Question 27

What environmental impacts resulted from the 2004 Indian Ocean tsunami?

Answer 27

Saltwater contamination, destruction of mangroves and coral reefs ## Footnote The ecological damage affected local biodiversity and habitats.

Question 28

What international response was prompted by the 2004 Indian Ocean tsunami?

Answer 28

A massive international humanitarian response ## Footnote Countries and organizations worldwide provided aid and support.

Question 29

What system was created in response to the 2004 Indian Ocean tsunami?

Answer 29

Indian Ocean Tsunami Warning System ## Footnote Established in 2006 to improve preparedness for future tsunamis.

Question 30

Give an example of an intraplate volcano.

Answer 30

Hawaii ## Footnote Hawaii is formed from a hotspot, demonstrating volcanic activity away from plate boundaries.

Question 31

What is an example of an intraplate earthquake?

Answer 31

Jishishan earthquake, China ## Footnote This earthquake occurred within a tectonic plate rather than at a plate boundary.

Question 32

What are examples of primary volcanic hazards?

Answer 32

* Lava flows * Pyroclastic flows * Volcanic gases ## Footnote These hazards can cause immediate destruction during eruptions.

Question 33

What are examples of secondary volcanic hazards?

Answer 33

* Lahars * Ash fall * Volcanic tsunamis ## Footnote These hazards can occur after the initial eruption, causing further damage.

Question 34

What is an example of a tsunami?

Answer 34

2004 Indian Ocean tsunami ## Footnote This tsunami was one of the most devastating in history.

Question 35

What is the definition of the lithosphere?

Answer 35

The rigid outer layer of the Earth, including the crust and uppermost mantle; divided into plates ## Footnote The lithosphere is essential for understanding plate tectonics.

Question 36

Define the asthenosphere.

Answer 36

A semi-molten layer beneath the lithosphere that enables tectonic plate movement ## Footnote The asthenosphere's properties allow for the movement of the lithospheric plates.

Question 37

What does the Plate Tectonics Theory state?

Answer 37

Earth's lithosphere is divided into plates that move due to convection currents ## Footnote This theory explains many geological phenomena, including earthquakes and volcanic activity.

Question 38

What is a convergent boundary?

Answer 38

A plate boundary where two plates move towards each other, often forming subduction zones or mountains ## Footnote Convergent boundaries are associated with significant geological activity.

Question 39

What is a divergent boundary?

Answer 39

A boundary where two plates move apart, creating features like mid-ocean ridges and rift valleys ## Footnote Divergent boundaries are key sites for new crust formation.

Question 40

Define a conservative boundary.

Answer 40

A boundary where two plates slide past one another, causing shallow but potentially powerful earthquakes ## Footnote These boundaries are characterized by the lateral movement of plates.

Question 41

What is a subduction zone?

Answer 41

A region where an oceanic plate sinks beneath another plate into the mantle at a convergent boundary ## Footnote Subduction zones are often associated with volcanic arcs.

Question 42

Explain the Benioff Zone.

Answer 42

A zone of earthquake activity along a subducting slab, extending to depths of up to 700 km ## Footnote This zone is a key area for understanding earthquake distribution.

Question 43

What is a mantle plume?

Answer 43

A rising column of hot mantle material that causes volcanic activity away from plate boundaries ## Footnote Mantle plumes are responsible for hotspots like Hawaii.

Question 44

What is an intra-plate earthquake?

Answer 44

An earthquake occurring within a tectonic plate, not at a plate boundary ## Footnote These earthquakes can occur far from tectonic plate edges.

Question 45

What is a locked fault?

Answer 45

A fault segment that is stuck due to friction, storing strain that may be released as an earthquake ## Footnote Locked faults can lead to significant seismic events when they finally slip.

Question 46

What is the focus (hypocentre) of an earthquake?

Answer 46

The point within the Earth where an earthquake originates ## Footnote Understanding the focus is crucial for earthquake analysis.

Question 47

What is the epicentre of an earthquake?

Answer 47

The point on the Earth’s surface directly above the earthquake focus ## Footnote The epicentre is often used to refer to the location of the earthquake's impact.

Question 48

Describe oceanic crust.

Answer 48

Dense, thin crust beneath the oceans, composed mostly of basalt ## Footnote Oceanic crust is generally younger than continental crust.

Question 49

Describe continental crust.

Answer 49

Thicker, less dense crust beneath continents, composed mostly of granite ## Footnote Continental crust is older and more complex than oceanic crust.

Question 50

What are seismic waves?

Answer 50

Vibrations from earthquakes, including P-waves, S-waves, and surface waves ## Footnote Seismic waves are critical for understanding earthquake mechanics.

Question 51

What is slab pull?

Answer 51

A process where the sinking of a subducting plate pulls the rest of the plate behind it ## Footnote Slab pull is a significant force in plate tectonics.

Question 52

What is ridge push?

Answer 52

The force exerted by cooling, descending lithosphere at divergent boundaries, pushing plates apart ## Footnote Ridge push contributes to plate movement at mid-ocean ridges.

Question 53

What is palaeomagnetism?

Answer 53

The record of Earth's past magnetic field in rocks, used as evidence for sea-floor spreading ## Footnote Palaeomagnetism provides insights into the history of plate tectonics.