Earthquakes Flashcards

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1
Q

Where do earthquakes occur?

A

Nearly all earthquakes occur at plate boundaries.

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2
Q

Where is one of the most deadly subduction zones located?

A

The subduction zone off the coast of Japan.

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3
Q

What is happening at the Japan Subduction zone?

A

The heavier Pacific Plate is being dragged under the Eurasian Plate.

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4
Q

How many earthquakes hit Japan every year?

A

About 1,500

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5
Q

What is Disaster Prevention Day?

A

This takes place on the Anniversary of the Great Kanto Earthquake of 1923 which killed 100,000 people.

Disaster preparations are taken nationwide. (1st of September)

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6
Q

Where do the most common and intense earthquakes occur at?

A

At subduction zones at convergent boundaries.

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7
Q

Give an example of a recent earthquake that occurred at a subduction zone.

A

The Japan Earthquake of 2011.

Due to the focus being under the ocean, a tsunami occurred also.

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8
Q

Apart from Japan, where else are earthquakes common?

A

Along the boundary between China and India.

Here two continental plates (the Indo-Australian and Eurasian) collide resulting in the formation of the Himalayas.

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9
Q

Why are the earthquakes that occur in China and India dangerous?

A

While they are not as powerful as those at subduction zones:

The relatively shallow depth of the focus means that the seismic waves do not have as far to travel.

They can cause a lot of damage to the surface.

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10
Q

Give an example of an earthquake that occurred in Nepal.

A

The Nepal Earthquake of 2015

Killed 8,000 people
Damaged 130,000 buildings
Deadliest day on Everest- 22 people were killed.

The Indian plate is converging on the Eurasian plate at a rate of 5 cm per year

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11
Q

Give an example of an earthquake in China.

A

The Sichuan Earthquake of 2008

Killed 69,000 people
5 million homeless.

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12
Q

What other plate boundary do earthquakes occur at?

America

A

Passive/Transform boundaries.

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13
Q

Name a passive/transform boundary.

A

The San Andreas Fault in California

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14
Q

What are seismic waves?

A

The energy released from an earthquake

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15
Q

What are foreshocks?

A

A major earthquake may be proceeded by smaller earthquakes

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16
Q

What are aftershocks?

A

Smaller earthquakes that follow after a major earthquake

17
Q

What is the epicenter?

A

The point on the surface directly above the focus, where tremors are the strongest and the worst damage occurs

18
Q

What is the focus?

A

The point deep in the Earth’s crust where the earthquake originates. If the focus is under the sea a tsunami will occur

19
Q

What factors can help geologists predict earthquakes?

A
  • Measuring rock stress
  • Measuring radon gas emissions
  • Changes in water and oil levels
  • Unusual animal behaviour
  • Seismic Gaps
  • Early warning systems
20
Q

What factors affect the damage caused by an earthquake?

A
  • Economic development
  • Population density
  • Time of day
  • Rock type
  • Depth of focus
  • Energy and duration
21
Q

Name the impacts of earthquakes

A
  • Soil liquefaction
  • Fire and service disruption
  • Falling debris
  • Tsunamis
22
Q

How do you reduce the effects of an earthquake?

A
  • Earthquake drills
  • Efficient urban planning
  • Early warning systems
  • Earthquake proof buildings/infrastructure
23
Q

Name the two ways to measure an earthquake

A
  • The Richter Scale

- The Mercalli Scale

24
Q

What does the Richter Scale measure?

A

Measures the intensity or magnitude of an earthquake/measures the energy released by an earthquake.
Named after Charles Richter

25
Q

What does the Mercalli scale measure?

A
  • Does not use instruments
  • Describes the effects or intensity of an earthquake based on human observations
  • Scale runs from 1 - 12