Layers of the Earth
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Questions and Answers

Which layer of the Earth is the thickest?

  • outer core
  • crust
  • inner core
  • mantle (correct)

Which layer of the Earth is composed of semi-molten rock?

  • mantle (correct)
  • crust
  • outer core
  • inner core

What is the main component of Earth's inner core?

  • magma
  • granite
  • iron and nickel (correct)
  • basalt

What drives the movement of tectonic plates?

<p>Convection currents in the mantle (A)</p> Signup and view all the answers

How thick is the Earth's crust on average?

<p>5-70 km (B)</p> Signup and view all the answers

Which type of crust is denser?

<p>oceanic (A)</p> Signup and view all the answers

Which material is most commonly found in continental crust?

<p>granite (D)</p> Signup and view all the answers

Which statement is true about oceanic crust?

<p>It is thinner and denser than continental crust. (A)</p> Signup and view all the answers

Where are the majority of volcanoes and earthquakes found?

<p>At plate boundaries (D)</p> Signup and view all the answers

What percentage of Earth's volcanoes are located along the Pacific Ring of Fire?

<p>75% (D)</p> Signup and view all the answers

What type of volcanic structure is formed at a destructive plate boundary?

<p>Stratovolcano (composite cone) (D)</p> Signup and view all the answers

What happens at a constructive plate boundary?

<p>Plates move apart (A)</p> Signup and view all the answers

Which is an example of a conservative plate boundary?

<p>The San Andreas Fault (A)</p> Signup and view all the answers

What geological feature is formed when two continental plates collide?

<p>Fold mountains (D)</p> Signup and view all the answers

What is a common characteristic of regions with a high density of earthquakes?

<p>High pressure due to plate activity (D)</p> Signup and view all the answers

What creates anomalies in the pattern of volcanic activity?

<p>Hotspots (D)</p> Signup and view all the answers

What is an opening in the Earth's crust that allows molten rock, ash, dust, and gases to escape?

<p>Volcano (B)</p> Signup and view all the answers

Which type of volcano is characterized by steep sides and alternating layers of lava and ash?

<p>Stratovolcano (A)</p> Signup and view all the answers

Which feature of a volcano is a channel through which magma travels to reach the Earth's surface?

<p>Main Vent (D)</p> Signup and view all the answers

Which stage of a volcano is described as erupting very recently or frequently?

<p>Active (C)</p> Signup and view all the answers

Where are shield volcanoes usually found?

<p>At constructive boundaries (A)</p> Signup and view all the answers

What is the name of the location where magma is stored beneath the ground?

<p>Magma chamber (A)</p> Signup and view all the answers

What type of lava do stratovolcanoes typically erupt?

<p>Viscous lava (B)</p> Signup and view all the answers

A volcano that has not erupted in historical times is known as what?

<p>Extinct (C)</p> Signup and view all the answers

What does the Mercalli Scale measure?

<p>The effects of an earthquake (B)</p> Signup and view all the answers

How many points are on the Mercalli Scale?

<p>12 (B)</p> Signup and view all the answers

Where are observations for the Mercalli Scale typically taken from?

<p>Near the epicenter (C)</p> Signup and view all the answers

What is a notable characteristic of the Mercalli Scale measurements?

<p>They are subjective viewpoints (D)</p> Signup and view all the answers

According to the Mercalli Scale, what happens at level 1?

<p>Not felt except by a very few under especially favorable circumstances (C)</p> Signup and view all the answers

What are hotspots?

<p>Stationary magma plumes deep in the Earth (D)</p> Signup and view all the answers

What causes the crust to dome and crack?

<p>Pressure from magma plumes (A)</p> Signup and view all the answers

What happens to a volcano as the crust moves over the hotspot?

<p>It becomes dormant and extinct (B)</p> Signup and view all the answers

Which of the following is a primary volcanic hazard?

<p>Pyroclastic flow (D)</p> Signup and view all the answers

What is acidification caused by?

<p>Sulfur emissions from volcanoes (C)</p> Signup and view all the answers

Which of the following is NOT a negative impact of volcanic hazards?

<p>Increase in tourism (A)</p> Signup and view all the answers

What opportunity does geothermal energy provide near volcanoes?

<p>Generating electricity (A)</p> Signup and view all the answers

What is a benefit of lava and ash deposits from volcanic eruptions?

<p>Providing valuable nutrients for soil (C)</p> Signup and view all the answers

Where is Eyjafjallajökull (E-15) located?

<p>Iceland (B)</p> Signup and view all the answers

What was a primary short-term impact of the Eyjafjallajökull eruption on farming?

<p>Wet and compact ash making farming difficult (C)</p> Signup and view all the answers

What measure was suggested to farmers to prevent contamination of livestock water supplies?

<p>Avoid allowing livestock to drink from water sources contaminated by ash or lava (A)</p> Signup and view all the answers

Which type of tourism increased due to the Eyjafjallajökull eruption?

<p>Volcanic tourism (B)</p> Signup and view all the answers

What causes earthquakes most frequently?

<p>Plate boundaries, particularly conservative and destructive plate boundaries (D)</p> Signup and view all the answers

What is the focus in relation to an earthquake?

<p>The point at which the earthquake occurs underground (C)</p> Signup and view all the answers

How much stronger is a 6-magnitude earthquake compared to a 5-magnitude earthquake on the Richter Scale?

<p>10 times stronger (B)</p> Signup and view all the answers

What do seismic or shock waves do during an earthquake?

<p>Travel through the earth causing the shaking of the ground (C)</p> Signup and view all the answers

Which factor does the Volcanic Explosivity Index (VEI) depend on?

<p>Volume of erupted tephra (C)</p> Signup and view all the answers

What is one method used to measure earthquakes occurring near a volcano?

<p>Seismometers (B)</p> Signup and view all the answers

Which system is used to monitor changes in the landscape near a volcano?

<p>Global positioning systems (GPS) satellites (D)</p> Signup and view all the answers

What technique involves using cameras to monitor heat sources within the crust of a volcano?

<p>Thermal imaging (A)</p> Signup and view all the answers

In reducing the impacts of volcanoes, which method involves creating channels and setting off explosives?

<p>Lava flow diversion (A)</p> Signup and view all the answers

What is the purpose of mudflow barriers in volcanic regions?

<p>To absorb the force of the mudflow and trap large debris (B)</p> Signup and view all the answers

How can building design help reduce the impacts of volcanic eruptions?

<p>Reinforced roofs to prevent collapse (B)</p> Signup and view all the answers

Which of these methods is used to educate the population about volcanic hazards?

<p>Educating people on danger signs and evacuation routes (D)</p> Signup and view all the answers

What tool is used to monitor earth tremors for earthquake prediction?

<p>Seismometer (B)</p> Signup and view all the answers

How can building guidelines help protect against earthquakes?

<p>By using rubber shock absorbers in the foundations (B)</p> Signup and view all the answers

Why is predicting the exact time of an earthquake very difficult despite knowing where they are likely to occur?

<p>Because of the complexity of the Earth's crust (D)</p> Signup and view all the answers

Which of the following is NOT a feature used in buildings to withstand earthquakes?

<p>Heavier walls to counteract movement (D)</p> Signup and view all the answers

How do earthquake drills benefit residents in earthquake-prone areas?

<p>They increase people's chances of surviving an earthquake (B)</p> Signup and view all the answers

Why might someone continue to live in an earthquake-prone area for sentimental reasons?

<p>Because they have lived there all their lives (B)</p> Signup and view all the answers

Which of these features is most likely included in building codes to reduce earthquake impacts?

<p>Lightweight roofs (B)</p> Signup and view all the answers

What is a common practice in Japan to prepare for earthquakes?

<p>Earthquake drills in schools (C)</p> Signup and view all the answers

Where did the magnitude 9 earthquake occur on 11 March 2011?

<p>Near the Japanese coastline (C)</p> Signup and view all the answers

How high were the original anti-tsunami defences built by Japan?

<p>12 meters (A)</p> Signup and view all the answers

How many people were displaced by the Japan earthquake and tsunami?

<p>130,927 (D)</p> Signup and view all the answers

What caused the flooding of Fukushima plant's generators and electrical wiring?

<p>A 9 meter high wave (D)</p> Signup and view all the answers

What was one of the immediate responses to the Japan earthquake?

<p>Setting up field hospitals (C)</p> Signup and view all the answers

What is the height of the new tsunami barriers built after the earthquake?

<p>18 meters (A)</p> Signup and view all the answers

What annual event does Japan conduct to prepare for earthquake emergencies?

<p>Earthquake and tsunami drill (B)</p> Signup and view all the answers

What major disaster occurred at the Fukushima plant due to the earthquake?

<p>Meltdown of seven reactors (D)</p> Signup and view all the answers

What is the minimum wind speed for a weather system to be classified as a tropical cyclone?

<p>120 km/h (C)</p> Signup and view all the answers

In which direction does the Coriolis Effect deflect the wind in the southern hemisphere?

<p>To the left (C)</p> Signup and view all the answers

Which characteristic is NOT part of a tropical cyclone's formation?

<p>Cold air rising quickly (A)</p> Signup and view all the answers

At what sea temperature do tropical cyclones typically form?

<p>27°C (A)</p> Signup and view all the answers

Which category on the Saffir-Simpson Hurricane Wind Scale represents wind speeds over 156 km/h?

<p>Category 5 (A)</p> Signup and view all the answers

During which season do tropical cyclones occur most commonly?

<p>Early autumn (D)</p> Signup and view all the answers

What is a significant hazard caused by the heavy rainfall from tropical cyclones?

<p>Flash flooding (D)</p> Signup and view all the answers

How high can storm surges caused by tropical cyclones reach?

<p>10 meters (D)</p> Signup and view all the answers

Flashcards

Inner Core

The Earth's innermost layer, solid, made of iron and nickel, extremely hot.

Outer Core

Liquid layer surrounding the inner core, also made of iron and nickel.

Mantle

Thickest layer of the Earth beneath the crust, semi-molten rock (magma).

Crust

Thin outer layer of the Earth, rocky.

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Plate Tectonics

Movement of Earth's crustal plates.

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Tectonic Plate

A section of the Earth's crust.

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Tectonic Plate Boundary

Where two or more plates meet.

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Oceanic Crust

Thinner, denser crust under the oceans.

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Continental Crust

Thicker, less dense crust that forms continents.

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Earthquake

Shaking and vibration of the Earth's crust.

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Volcano

Opening in the Earth's crust allowing molten rock to escape.

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Constructive Boundary

Plates move apart, creating new crust.

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Destructive Boundary

Plates collide, one plate is subducted under the other

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Collision Boundary

Continental plates collide, forming mountains.

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Conservative Boundary

Plates slide past each other.

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Ring of Fire

Region around the Pacific Ocean with many volcanoes and earthquakes.

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Volcanic Explosivity Index (VEI)

Scale to measure the explosiveness of a volcano.

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Primary Hazard

Direct hazard linked to a natural event.

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Secondary Hazard

Indirect hazard following a natural event.

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Richter Scale

Scale measuring earthquake magnitude.

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Focus

Point of origin of an earthquake.

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Epicenter

Point on Earth's surface directly above the focus.

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Convection Currents

Circulating currents in the Earth's mantle driving plate movement.

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Study Notes

Layers of the Earth

  • The Earth is composed of four main layers: inner core, outer core, mantle, and crust
  • Inner core: solid, iron and nickel, temperatures up to 5,500°C
  • Outer core: liquid, iron and nickel
  • Mantle: thickest section, approximately 2,900 km, semi-molten rock (magma)
  • Crust: thin, rocky outer layer, approximately 5-70 km thick

Plate Tectonics

  • Movement of plates and activity inside the Earth is called plate tectonics
  • Tectonic plate: section of the Earth's crust
  • Tectonic plate boundary: area where two or more plates meet
  • Convection currents in the mantle cause plate movement
  • Plates move apart where convection currents move in opposite directions

Types of Crust

  • Oceanic crust: thinner (5-10 km), more dense, often subducted
  • Continental crust: thicker (30-50 km), less dense, cannot be subducted

Distribution of Earthquakes and Volcanoes

  • Majority of volcanoes and earthquakes occur at plate boundaries
  • Friction and pressure at plate boundaries cause earthquakes and volcanic activity

The Pacific Ring of Fire

  • 75% of Earth's volcanoes, 90% of Earth's earthquakes occur along the Ring of Fire

Plate Boundaries

  • Destructive plate boundary: oceanic and continental plates converge, oceanic plate is subducted
  • Constructive plate boundary: plates move apart, magma rises to fill the gap, new crust is formed
  • Collision plate boundary: continental plates collide, forming fold mountains
  • Conservative plate boundary: plates slide past each other, no creation or destruction of crust

Volcanoes

  • Definition: opening in the Earth's crust allowing molten rock, ash, and gases to escape
  • Can occur at destructive and constructive plate boundaries, and over hotspots
  • Types of volcanoes: stratovolcano (composite cone) and shield volcano

Volcanic Hazards

  • Primary hazards: direct hazards associated with natural events (short-term)
  • Secondary hazards: indirect hazards associated with natural events (long-term)
  • Examples: pyroclastic flow, acidification, lahars

Impacts and Opportunities of Volcanic Hazards

  • Negative impacts: loss of life, destruction of settlements, infrastructure damage, environmental damage
  • Opportunities: tourism, fertile soil, geothermal energy, creation of new land

Measuring Volcanic Hazards

  • Volcanic Explosivity Index (VEI) Scale: 0 (non-explosive) to 8 (mega-colossal)
  • Seismometers, GPS satellites, thermal imaging, and infrared camera imagery used to monitor volcanic activity

Reducing Vulnerability

  • Monitoring volcanic activity, hazard mapping, and planning
  • Building design, lava flow diversion, and mudflow barriers

Earthquakes

  • Definition: shaking and vibration of the Earth's crust due to plate movement
  • Focus: point where the earthquake occurs
  • Epicentre: point directly above the focus on the Earth's surface
  • Seismic waves: shock waves that start at the focus and travel through the Earth

Measuring Earthquakes

  • Richter Scale: measures the magnitude of an earthquake
  • Mercalli Scale: measures the effects of an earthquake on a 12-point scale

Reducing the Impacts of Earthquakes

  • Prediction: using seismometers to monitor earth tremors
  • Protection: building codes, rubber shock absorbers, steel frames, and open areas
  • Preparation: drills, emergency services, and resident preparedness

Why People Continue to Live in Hazardous Zones

  • Reasons: employment, scenery, family, friends, sentimental value, and preparedness

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Learn about the four main layers of the Earth: the inner core, outer core, mantle, and crust. Understand their composition, temperature, and characteristics.

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