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What is the focus of an earthquake?
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What is the focus of an earthquake?
The focus of an earthquake is the point below the Earth's surface where the earthquake starts.
Define the term epicentre.
The epicentre is the point on the Earth's surface directly above the focus of an earthquake.
True or False?
Most earthquakes occur far from plate boundaries.
False.
Most earthquakes (about 95%) occur close to or at plate margins.
What are P waves?
P waves are primary seismic waves that are the fastest, reach the surface first, travel through liquids and solids, and cause backwards and forward shaking.
Define the term liquefaction.
Liquefaction is when shaking causes loose or saturated soils to lose their strength and act like a liquid rather than a solid.
What is the Ring of Fire?
The Ring of Fire is the area surrounding the Pacific Ocean where many earthquakes occur.
What are S waves?
S waves are secondary seismic waves that are slower than P waves, only travel through solids, and cause a sideways motion.
True or False?
Intra-plate earthquakes occur at plate margins.
False.
Intra-plate earthquakes are those that do not happen at plate margins.
What is the name of a large wave caused by an earthquake beneath the sea bed that lifts water?
A tsunami is a large wave created when an earthquake occurs beneath the sea bed, displacing water and forcing it upwards.
Which type of seismic wave is the most damaging?
L waves are surface seismic waves that are the slowest, cause a side-to-side motion, and are the most damaging.
What is magnitude in the context of earthquakes?
Magnitude is the energy released at the source (focus) of an earthquake.
Define the Moment Magnitude Scale (MMS).
The Moment Magnitude Scale (MMS) is used to measure the magnitude of earthquakes, ranging from 1 to 10.
True or False?
The Moment Magnitude Scale is a linear scale.
False.
The Moment Magnitude Scale is a logarithmic scale.
What does the Modified Mercalli Intensity Scale measure?
The Modified Mercalli Intensity Scale measures the intensity of an earthquake, which is its impact on people, as well as on the built and natural environments.
Define seismic gap theory.
Seismic gap theory suggests that if there has been little or no earthquake activity at a plate margin for a long time, it is more likely to experience a large earthquake in the future.
True or False?
It is possible to predict earthquakes accurately.
False.
It is not possible to predict earthquakes accurately.
What are foreshocks?
Foreshocks are pre-cursor earthquakes that may indicate a larger earthquake will follow.
What does a strainmeter measure?
A strainmeter measures deformation, which might indicate that pressure is building up before an earthquake.
Concentrations of which gas in the atmosphere may increase before an earthquake?
Concentrations of radon gas in the atmosphere may increase before an earthquake.
What is the probability of a 6.7 magnitude earthquake in the Los Angeles area within the next 30 years?
The probability of a 6.7 magnitude earthquake in the Los Angeles area within the next 30 years is 60%.
What are primary impacts of earthquakes?
Primary impacts of earthquakes are the immediate effects of the hazard, such as injuries and deaths, and damage to property and infrastructure.
True or False?
The 2015 Gorkha earthquake in Nepal occurred on a divergent plate boundary.
False.
The 2015 Gorkha earthquake in Nepal occurred on a collision plate boundary where the Indian plate collides with the Eurasian plate.
What was the magnitude of the 2015 Gorkha earthquake in Nepal?
The magnitude of the 2015 Gorkha earthquake in Nepal was 7.8.
Give two examples of primary economic impacts of earthquakes.
Primary economic impacts include the costs of:
Repair and reconstruction of buildings and infrastructure.
Disruption to trade and economic activity.
Loss of income and employment.
Immediate responses, e.g. food aid, temporary shelter, medical treatment.
What percentage of Nepal's GDP was tourism before the 2015 earthquake?
Tourism accounted for 8% of Nepal's GDP before the 2015 earthquake.
True or False?
The 2015 Gorkha earthquake had no impact on Nepal's forest cover.
False.
The 2015 Gorkha earthquake damaged or destroyed large areas (12,000 hectares) of forest and vegetation.
What was the estimated economic damage caused by the 2015 Gorkha earthquake?
The estimated economic damage caused by the 2015 Gorkha earthquake was between US$7-10 billion, or about 35% of Nepal's GDP.
How many avalanches and landslides were triggered by the 2015 Gorkha earthquake?
The 2015 Gorkha earthquake triggered more than 3000 avalanches and landslides.
Give two social secondary impacts of earthquakes.
Social secondary impacts include:
Mental health issues, e.g. stress, anxiety, depression.
Homelessness.
Disruption to services such as healthcare and education.
Loss of cultural heritage sites.
The 2015 Nepal earthquake left how many people in temporary shelter two years later?
Two years later, 70% of displaced people were still in temporary shelters.
True or False?
Long-term responses include providing shelter, medicines, food and water.
False.
Long-term responses are measures taken to reduce the impact of future earthquakes such as hazard planning and stricter building regulations.
Define adaption in the context of earthquakes.
Adaption is a change in behaviour to reduce the risk of earthquakes, for example, keeping an emergency bag ready.
True or False?
Building codes are an example of a short-term response to earthquakes.
False.
Building codes are an example of a long-term response to earthquakes.
What is Japan's Disaster Prevention Day?
Japan's Disaster Prevention Day is an annual event held on September 1st to prepare communities and improve evacuation and response through regular drills.
What is hazard mapping?
Hazard mapping is the process of identifying areas at most risk of hazards like liquefaction or tsunamis. The activities that take place there are then limited.
True or False?
It is possible to prevent earthquakes from occurring.
False.
It is impossible to prevent earthquakes from occurring.
What is the purpose of earthquake drills?
Earthquake drills are conducted to provide people with education about what to do in the event of an earthquake.
Define mitigation in the context of earthquake management.
Mitigation refers to actions aimed at reducing the threat of earthquakes by altering the environment, such as building tsunami walls or constructing earthquake-resistant buildings.
How much did the Asian Development Bank provide for rebuilding after the 2015 Nepal earthquake?
The Asian Development Bank provided US$200 million for rebuilding after the 2015 Nepal earthquake.
True or False?
Shutters are one method of improving building construction to reduce the impact of earthquakes.
True.
Shutters are one method of improving building construction to reduce the impact of earthquakes.