R.E volcanoes, earthquakes Flashcards

1
Q

Where are volcanoes found?

A

at destructive and constructive plate margins

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2
Q

How does a volcano happen at a destructive margin?

A

oceanic plate goes into the mantle,melted /destroyed

pool of magma forms, which rises through cracks erupts onto surface.

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3
Q

what are the cracks in the earth called?

A

vents

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4
Q

What is magma called once it reaches the surface?

A

lava

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5
Q

How do volcanoes at constructive margins happen?

A

Magma rises through gap of plates moving apart

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6
Q

Volcanoes also form on mantle what is this called?

A

Hotspot e.g Hawaii

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7
Q

Name 3 types of volcanoes?

A

shield, composite and dome

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8
Q

What are the layers in a composite volcano?

A

ash and thick lava (into a steep volcano)

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9
Q

Give example of composite volcano?

A

Mount Fuji ,Japan

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10
Q

How is a shield volcano formed?

A

Only runny lava, flows quickly, spreads wide forming a low flat volcano.

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11
Q

Give example of a shield volcano?

A

Mauna Loa, Hawaiian Islands

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12
Q

How is a dome volcano formed?

A

Only thick lava, flows slowly ,hardens quickly forming steep sides.

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13
Q

Names ways scientists predict volcanic eruptions?

A

tiny earthquakes, escaping gas, shape changes in the earth (bulges in land where magma has built up.

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14
Q

Where are super volcanoes formed?

A

at destructive plate margins and hotspots

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15
Q

How are super volcanoes formed?

A

magma rises up to form a magma basin below the surface, causing a circular bulge kms wide,
bulge cracks, lava escapes through vents, causing earthquakes, gigantic plumes of ash and rock,
lava empties bulge collapses leaving a big crater ( caldera)

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16
Q

Characteristic of a super volcano?

A

Flat, cover a large area, have a caldera ( regular volcanos have a crater)

17
Q

Give example of a caldera filled with water?

A

Lake Toba

18
Q

Name the last supervolcano to have erupted?

A

Lake Toba 74,000 years ago

19
Q

Consequences of a super volcano?

A

thousands of cubic kms of rock, ash and lava.
cloud of thick super-heated gas and ash flow at high-speed across 10s of miles.
ash will block out daylight could trigger a mini ice age
ash will settle over 100s sq kms burying everything.

20
Q

When does an earthquake happen?

A

plates can get stuck, when they become unstuck it causes an earthquake

21
Q

what type of plate margins do earthquakes happen at?

A

All 3

22
Q

What are destructive type earthquakes?

A

tension builds when 1 plate gets stuck as its moving past the other into the mantle

23
Q

What are constructive type earthquakes?

A

tension builds along cracks in the plates as they move apart

24
Q

What are conservative type earthquakes?

A

plates are grinding past each other and get stuck

25
Q

What is an earthquake?

A

When the plates jerk past each other sending shockwaves

26
Q

What are shockwaves?

A

Vibrations (earthquake)

27
Q

What is the focus of the earthquake?

A

The point in the earth where the quake starts

28
Q

Where are the shockwaves strongest?

A

Focus

29
Q

Where is the epicentre of an earthquake?

A

the point on the surface straight above the focus

30
Q

Can earthquakes be measured?

A

yes , Richter scale and Mercalli scale

31
Q

What is the energy released by an earthquake called?

A

magnitude

32
Q

How is magnitude measured?

A

seismometer (an arm that moves with the vibrations)

33
Q

What is logarithmic?

A

an earthquake with the magnitude of 5 is 10 times more powerful than 4

34
Q

What magnitude is a major earthquake ?

A

above 5

35
Q

What does Mercalli scale measure?

A

the effects of the earthquake.

36
Q

What are affects measured by?

A

eye witness observation, words or photo. scale 1-12

37
Q

What effect does an earthquake at sea have?

A

tsunamis

38
Q

What is a tsunami?

A

a series of enormous waves, caused by huge amounts of water being displaced