77 Questions
Which layer of the Earth is the thickest?
mantle
Which layer of the Earth is composed of semi-molten rock?
mantle
What is the main component of Earth's inner core?
iron and nickel
What drives the movement of tectonic plates?
Convection currents in the mantle
How thick is the Earth's crust on average?
5-70 km
Which type of crust is denser?
oceanic
Which material is most commonly found in continental crust?
granite
Which statement is true about oceanic crust?
It is thinner and denser than continental crust.
Where are the majority of volcanoes and earthquakes found?
At plate boundaries
What percentage of Earth's volcanoes are located along the Pacific Ring of Fire?
75%
What type of volcanic structure is formed at a destructive plate boundary?
Stratovolcano (composite cone)
What happens at a constructive plate boundary?
Plates move apart
Which is an example of a conservative plate boundary?
The San Andreas Fault
What geological feature is formed when two continental plates collide?
Fold mountains
What is a common characteristic of regions with a high density of earthquakes?
High pressure due to plate activity
What creates anomalies in the pattern of volcanic activity?
Hotspots
What is an opening in the Earth's crust that allows molten rock, ash, dust, and gases to escape?
Volcano
Which type of volcano is characterized by steep sides and alternating layers of lava and ash?
Stratovolcano
Which feature of a volcano is a channel through which magma travels to reach the Earth's surface?
Main Vent
Which stage of a volcano is described as erupting very recently or frequently?
Active
Where are shield volcanoes usually found?
At constructive boundaries
What is the name of the location where magma is stored beneath the ground?
Magma chamber
What type of lava do stratovolcanoes typically erupt?
Viscous lava
A volcano that has not erupted in historical times is known as what?
Extinct
What does the Mercalli Scale measure?
The effects of an earthquake
How many points are on the Mercalli Scale?
12
Where are observations for the Mercalli Scale typically taken from?
Near the epicenter
What is a notable characteristic of the Mercalli Scale measurements?
They are subjective viewpoints
According to the Mercalli Scale, what happens at level 1?
Not felt except by a very few under especially favorable circumstances
What are hotspots?
Stationary magma plumes deep in the Earth
What causes the crust to dome and crack?
Pressure from magma plumes
What happens to a volcano as the crust moves over the hotspot?
It becomes dormant and extinct
Which of the following is a primary volcanic hazard?
Pyroclastic flow
What is acidification caused by?
Sulfur emissions from volcanoes
Which of the following is NOT a negative impact of volcanic hazards?
Increase in tourism
What opportunity does geothermal energy provide near volcanoes?
Generating electricity
What is a benefit of lava and ash deposits from volcanic eruptions?
Providing valuable nutrients for soil
Where is Eyjafjallajökull (E-15) located?
Iceland
What was a primary short-term impact of the Eyjafjallajökull eruption on farming?
Wet and compact ash making farming difficult
What measure was suggested to farmers to prevent contamination of livestock water supplies?
Avoid allowing livestock to drink from water sources contaminated by ash or lava
Which type of tourism increased due to the Eyjafjallajökull eruption?
Volcanic tourism
What causes earthquakes most frequently?
Plate boundaries, particularly conservative and destructive plate boundaries
What is the focus in relation to an earthquake?
The point at which the earthquake occurs underground
How much stronger is a 6-magnitude earthquake compared to a 5-magnitude earthquake on the Richter Scale?
10 times stronger
What do seismic or shock waves do during an earthquake?
Travel through the earth causing the shaking of the ground
Which factor does the Volcanic Explosivity Index (VEI) depend on?
Volume of erupted tephra
What is one method used to measure earthquakes occurring near a volcano?
Seismometers
Which system is used to monitor changes in the landscape near a volcano?
Global positioning systems (GPS) satellites
What technique involves using cameras to monitor heat sources within the crust of a volcano?
Thermal imaging
In reducing the impacts of volcanoes, which method involves creating channels and setting off explosives?
Lava flow diversion
What is the purpose of mudflow barriers in volcanic regions?
To absorb the force of the mudflow and trap large debris
How can building design help reduce the impacts of volcanic eruptions?
Reinforced roofs to prevent collapse
Which of these methods is used to educate the population about volcanic hazards?
Educating people on danger signs and evacuation routes
What tool is used to monitor earth tremors for earthquake prediction?
Seismometer
How can building guidelines help protect against earthquakes?
By using rubber shock absorbers in the foundations
Why is predicting the exact time of an earthquake very difficult despite knowing where they are likely to occur?
Because of the complexity of the Earth's crust
Which of the following is NOT a feature used in buildings to withstand earthquakes?
Heavier walls to counteract movement
How do earthquake drills benefit residents in earthquake-prone areas?
They increase people's chances of surviving an earthquake
Why might someone continue to live in an earthquake-prone area for sentimental reasons?
Because they have lived there all their lives
Which of these features is most likely included in building codes to reduce earthquake impacts?
Lightweight roofs
What is a common practice in Japan to prepare for earthquakes?
Earthquake drills in schools
Where did the magnitude 9 earthquake occur on 11 March 2011?
Near the Japanese coastline
How high were the original anti-tsunami defences built by Japan?
12 meters
How many people were displaced by the Japan earthquake and tsunami?
130,927
What caused the flooding of Fukushima plant's generators and electrical wiring?
A 9 meter high wave
What was one of the immediate responses to the Japan earthquake?
Setting up field hospitals
What is the height of the new tsunami barriers built after the earthquake?
18 meters
What annual event does Japan conduct to prepare for earthquake emergencies?
Earthquake and tsunami drill
What major disaster occurred at the Fukushima plant due to the earthquake?
Meltdown of seven reactors
What is the minimum wind speed for a weather system to be classified as a tropical cyclone?
120 km/h
In which direction does the Coriolis Effect deflect the wind in the southern hemisphere?
To the left
Which characteristic is NOT part of a tropical cyclone's formation?
Cold air rising quickly
At what sea temperature do tropical cyclones typically form?
27°C
Which category on the Saffir-Simpson Hurricane Wind Scale represents wind speeds over 156 km/h?
Category 5
During which season do tropical cyclones occur most commonly?
Early autumn
What is a significant hazard caused by the heavy rainfall from tropical cyclones?
Flash flooding
How high can storm surges caused by tropical cyclones reach?
10 meters
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
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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