Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Plate boundaries and their landforms&features > Living with tectonic hazards (3) > Flashcards

Living with tectonic hazards (3) Flashcards

1
Q

What is a volcano and where can we find them?

A
  • a volcano is a landform formed by magma ejected from mantle on earth’s surface
  • found mainly along convergent or divergent plate boundaries
  • a few found far away from plate boundaries (hotspots)
  • most volcanoes found along the Pacific Ring of Fire
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Parts of volcano

A
  • magma chamber
  • vent
  • pipe
  • crater
  • secondary cone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Magma chamber

A

-refers to a reservoir of molten rock located beneath the earth’s crust

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Vent

A

-refers to openings in the earth surface with a pipe leading into the magma chamber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pipe

A

-refers to the passageway through which magma rises

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Crater

A

-refers to bowl-shaped opening at top of volcano

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Secondary cone

A
  • during formation of volcano, vent may be blocked
  • forces magma to find a new exit route to the surface
  • a secondary cone of newer volcanic material will then form
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How are volcanoes formed?

A
  • about 25 to 150km below earth’s crust, rocks melt (due to subduction) due to high heat and these molten rocks are known as magma
  • magma and gases such as hydrogen and carbon dioxide will rise towards earths surface, form magma chamber
  • when cracks and fractures are formed, magma from magma chamber rises to surface thru the vent
  • magma is ejected onto the earth’s surface as lava
  • hot and liquid lava then piles up arnd the vent in successive layers to form a volcano
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Two types of volcanoes

A
  • stratovolcano

- shield volcano

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Stratovolcano: Where are they found?

A

-along convergent boundaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Stratovolcano: Examples

A
  • Mount Fuji, Japan

- Mount Vesuvius, Italy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Stratovolcano: Characteristics

A
  • conical shape
  • steep slopes
  • higher in height
  • secondary cones
  • narrow base
  • powerful eruptions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Stratovolcano: How are they formed?

A
  • developed from successive eruptions lava and ash
  • ash deposits contain coarser rock fragments ejected from the vent
  • after initial eruption, subsequent eruption ejects lava which covers soft ash and prevents it from being eroded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Shield volcano: Where are they usually found?

A

-along divergent boundaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Shield volcano: Examples

A

Mauna Loa, Hawaii

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Shield volcano: Characteristics

A
  • broad base
  • gentle slope
  • lower in height
  • non-explosive eruption
17
Q

Shield volcano: How are they formed?

A
  • formed when low-silica or basic lava is ejected
  • basic lava flow easily, spreads over a large area before solidifying
  • with successive eruptions, base of volcano increases in size as lava accumulates
18
Q

How and why are shape of volcanoes different?

A
  • dependent of viscosity of lava (thickness/stickiness)

- acidic/high silica vs basic/low silica lava

19
Q

Acidic/ high silica lava

A
  • higher viscosity, thicker, stickier
  • move slowly
  • does not flow far
  • loud explosions
  • produces steep-sided volcano
  • produced at destructive boundary
20
Q

Basic/low silica lava

A
  • lower viscosity
  • move rapidly
  • flows far
  • quiet explosions
  • produce gentle-sloping volcano
  • produced at constructive boundary
21
Q

What is released during a volcanic eruption?

A
  • lahar

- pyroclastic flows

22
Q

Lahars

A
  • volcanic mudflows created when water (from rain or melt water from glaciers) and ash mix
  • contain more rock debris (60 to 90 percent) compared to pyroclastic flow
  • can travel much further than pyroclastic flow (50 miles from volcano)
  • can move at the speed of a freight train (20 to 40 miles per hour)
  • overflows riverbanks, sweep away roads and towns
23
Q

Pyroclastic flows

A
  • avalanches containing hot volcanic ash and volcanic bombs
  • hot, heavy cloud of ash and gases roll above and races ahead of flow
  • on steep volcanoes pyroclastic can reach speeds of 100 miles per hour
24
Q

Risks of living near volcanoes

A
  • Destruction
  • landslides
  • pollution
  • change in temp
25
Q

Destruction

A
  • volcanic materials produced by volcanic eruptions include lava and rock fragments or volcanic bombs
  • lava with high temperatures of between 500 to 1400 degrees burns the areas it flows thru
  • low silica lava moves rapidly and flows over long distances, causing damage to larger areas
  • pyroclastic flow destroys everything in its path with hot rock fragments travelling at speeds greater than 80km/h
  • exposure to hot gases and ash can result in serious injury or even death
  • e.g Pompeii
26
Q

Landslides

A
  • can range from a few rock fragments falling from the volcano to landslides of several hundred of cubic kilometres
  • have the potential to obstruct river flow, causing floods, blocked roads and buried villages, farmlands
  • e.g. erruption of Nevado de Ruiz in Andes Mountain released a pyroclastic flow, mixed with glacial ice, triggered lahars , killing more than 20000 ppl in 1985
27
Q

Pollution

A
  • volcanic eruptions can release gases such as carbon an hydrogen monoxide, sulphur dioxide, carbon dioxide
  • ash particles ejected during a volcanic eruption has the potential to :
    1. eventually settle on ground, block sunlight, suffocate crops, cause severe respiratory problems for ppl and animals
    2. be carried by wind to areas further from the source, disrupt daily lives
  • e.g. eruption of Eyjafjallajokull in Iceland 2010 produced extensive volcanic ash clouds containing tiny particles of abrasive glass, sand and rock
  • caused the closure of air space over much of Europe
  • airline industry suffered a loss of US$ 1.8 billion
28
Q

Change in temperature

A
  • sulphur dioxide (from eruption) may react with water vapour and other chemicals in atmosphere to form sulphur-based articles
  • these articles reflect the sun’s energy back into space and temporarily cool the earth for periods of time
  • e.g. mt Pinatubo eruption in June 1991 caused global temp to drop by about 0.5 degrees between 1991 to 1993
29
Q

Why do people continue living near volcanic areas despite risks?

A
  • source of fertile soil for farming
  • source of raw materials
  • source of tourism/ revenue
  • source of energy
30
Q

Source of fertile soil for farming

A
  • lava and ash from volcanic eruptions break down to form fertile volcanic soils (favourable to agriculture)
  • e.g. the volcanic soils of Java and Bali in Indonesia support the cultivation of crops like tea, coffee and rice
31
Q

Source of raw materials

A
  • volcanic rocks can be rich in precious stones and minerals
  • can only be extracted after the upper layers of volcanic rocks are eroded (after millions of years)
  • e.g diamonds are heated and pressurized carbon that is cooled in magma pipes beneath earth’s surface
  • when refined it is used as industrial tools, in scientific research and as jewellery
  • e.g. volcanic rocks are also good resources for building materials and production of other daily items
  • in East Java (Indonesia), workers collect sulfur from active volcanoes
  • used to make matches, fertilizers and refine sugars
  • job opportunities for locals, income is higher, pay more taxes, overall economy benefits
32
Q

Source of tourism/revenue

A
  • volcanic areas provide a variety of activities for tourists to engage in
  • many people visit the volcanoes to hike, camp or enjoy the scenery
  • e.g. the Roman town of Pompeii Italy was buried by layers of ash from the nearby Mount Vesuvius when it erupted in 79CE, killing about 2000
  • unearthed site revealed buildings, pottery and mosaics intact
  • abt 3 mil ppl visit every year, creating jobs in tourism industry, income higher, country economy benefit due to taxes
33
Q

Source of energy (alternative energy)

A
  • when groundwater comes into contact with hot rocks beneath the surface, heats and erupts as hot water or steam
  • can be harnessed to drive turbines and produce electricity
  • e.g. most of Iceland’s electricity is generated from geothermal energy because of the large number of volcanoes in the country
  • over 70 percent of the homes in Iceland are heated by volcanic steam

Plate boundaries and their landforms&features (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions