tectonic processes and hazards

Question 1

what are volcanoes?

Answer 1

openings in the earth’s crust where gas, lava and ash erupt. Tectonic plates cause pressure to build up and magma and gases rise up reaching the surface

Question 2

why do volcanoes get bigger over time?

Answer 2

lava cools - forms rock - so as the volcano continues to erupt over time it gets bigger, as the rock builds up

Question 3

lava flows

Answer 3

• very hot (1000 degrees Celsius)
• move slowly (can be outrun)
• destroy everything in their path

Question 4

pyroclastic flows

Answer 4

• hot rock, lava and ash

- move at a very fast speed (cannot be outrun)

Question 5

tephra and ash falls

Answer 5

• volcanic rock and ash that erupt
• cause injury and death
• poor visibility
• slippery roads

Question 6

gas eruptions

Answer 6

• magma contains dissolved gases that release into the atmosphere
• they can travel thousands of miles

Question 7

lahars

Answer 7

• masses of rock, mud and water travel down sides of volcano
• caused when eruption melts snow or ice
• too fast to outrun - deadly

Question 8

what are hotspots?

Answer 8

• volcanoes that occur in the middle of plate margins

- plumes of hot magma rise up and erupt

Question 9

how is a chain of volcanic islands formed?

Answer 9

• as the plates move over the hotspot, the volcano is carried away with it and a new one forms

Question 10

measuring the size and magnitude of volcanoes?

Answer 10

The explosivity index

• height and amount
• duration of eruption
• qualitative terms

Question 11

predicting eruptions

Answer 11

• scientists can detect rock that breaks due to magma using seismograms
• surface changes shape
• changes to the tilt of the volcano

Question 12

what is an earthquake?

Answer 12

An earthquake is the result of a sudden release of stored energy in the Earth’s crust that creates seismic waves.

Question 13

hypocentre / focus

Answer 13

the point inside the crust from which the pressure is released

Question 14

epicentre

Answer 14

the point on the surface directly above the focus

Question 15

What is mantle convection?

Answer 15

Heat produced by the decay of radioactive elements in the Earth‘s core, heats the lower mantle creating convection currents

Question 16

What is slab pull?

Answer 16

Newly formed oceanic crust at mid ocean ridges becomes denser and thicker as it cools. It then sinks into the mantle

Question 17

Subduction?

Answer 17

One plate (oceanic) sub ducts underneath the other, and sinks into the mantle.

Question 18

Sea floor spreading

Answer 18

When magma is forced up from the mantle in mid ocean ridges, new oceanic crust is created. This new crust pushes plates apart

Question 19

Describe the features of

• inner core
• outer core

Answer 19

Inner - hottest part (mostly solid) 6000•c Iron

Outer - semi molten (iron and nickel) 4500-6000•

Question 20

What is the mantle?

Answer 20

The widest layer.
Surrounds the core of the earth
Between outer layer and crust

Question 21

What is the difference between oceanic crust and continental crust?

Answer 21

Oceanic - more dense but thinner and lines the ocean floors

Continental - older and thicker
Makes up the lithosphere
Covers all continents

Question 22

Oceanic + continental (destructive)

Answer 22

• Oceanic plate is subducted
• fold mountains created as a result of the collision
• earthquakes caused by friction
• volcanoes formed because of melting of the oceanic crust in the mantle

Question 23

Oceanic + oceanic (destructive)

Answer 23

The denser oceanic plate is subducted

• rise up to form separate island volcanoes
• shallow deep focus earthquakes formed here and are very powerful

Question 24

Continental + continental

Answer 24

AKA COLLISION MARGIN

• sediments crumple up to form high fold mountains
• compression can cause shallow focus earthquakes which are extremely powerful

Question 25

What are mid ocean ridges and how are they created?

Answer 25

Underwater mountain ranges across the ocean floor. They are created from rising magma that erupts onto the sea floor creating new land

Question 26

What are rift valleys?

Answer 26

When the plates move apart, the crust stretches and breaks into a set of parallel cracks (FAULT) the land then collapses

Question 27

Conservative plate margins

Answer 27

Plates sliding past each other. Include transform faults Powerful earthquakes as major pressure can build up from plates that get stuck (Eg San Andreas fault)

Question 28

Natural hazard?

Answer 28

Naturally occurring process that has the potential to affect people

Question 29

Natural disaster

Answer 29

Major natural hazard that causes significant social, environmental and economic damage

Question 30

Vulnerability

Answer 30

The ability to anticipate cope with, resist, and recover from a natural hazard

Question 31

What does a seismometer do?

Answer 31

Detects ground movement

Question 32

Moment magnitude scale factors?

Answer 32

- size of seismic waves - rock movement - area of fault broken by EQ - resistance of rocks affected

Question 33

What does it mean by a logarithmic scale?

Answer 33

Each number is 10 times the magnitude of the last number

Question 34

What does the term magnitude mean?

Answer 34

The amount of energy released at the epicentre

Question 35

What does the Mercalli intensity scale include

Answer 35

Observations from people who experience the earthquake. | Rated on a scale from 1 to X

Question 36

Ground shaking effects

Answer 36

Causes infrastructure to collapse resulting in injury and death

Question 37

Crustal Fracturing

Answer 37

The earths crust cracks leaving gaps

Question 38

What is liquefaction?

Answer 38

Violent shaking can cause rocks to the strength and become more liquid than solid. Therefore buildings can lose their foundation and collapse

Question 39

What is an intraplate earthquake?

Answer 39

They occur in the middle of plate margins far from the Boundary

Question 40

What is the tsunami?

Answer 40

A Sunami is a series of larger than normal waves, which are usually caused by volcanic eruptions or underwater earthquakes

Question 41

Define the term water column

Answer 41

The area of seawater from the surface to seafloor

Question 42

Impacts of tsunami

Answer 42

- sweeping away buildings + people - wash away soil destroying everything - change the landscape

Question 43

Why can’t we predict Tsunamis

Answer 43

Because we can’t predict earthquakes therefore we can only send out warnings

Question 44

What are early warning systems?

Answer 44

Use Seismic sensors to detect undersea earthquakes

Question 45

What does the DART system monitor?

Answer 45

It monitors changes in sealevel pressure. When Sunami waves are detected, the system sends the information through a satellite for warning systems

Question 46

Benioff zone

Answer 46

This is where major friction is created due to the colliding of plates, often resulting in earthquakes

Question 47

p waves

Answer 47

primary/pressure waves - fastest - travel through solids and liquids - shake in a back and forwards motion

Question 48

S waves

Answer 48

secondary waves - slower - only travel through solids - move sideways at right angle to direction - more damaging than p waves

Question 49

L waves

Answer 49

Love waves - slowest - most damaging - shake from side to side - focus all energy on earths surface

Question 50

how can a countries governance increase its vulnerability?

Answer 50

- building codes are often skipped - quality of infrastructure - efficiency of emergency services - level of corruption - how educated communities are on response

Question 51

How can economic and social conditions increase its vulnerability?

Answer 51

- more wealthy = able to afford protection - poor quality housing cannot withstand hazards - poor health care can cause disease outbreaks

Question 52

how can physical and environmental conditions increase vulnerability?

Answer 52

- high population density - more people at risk - rapid urbanisation - poor quality housing as it has been rushed due to high demand - if the accessibility of an area is difficult, it may delay emergency services