Earth Science: Natural Disasters: Causes and Effects
How Earth processes create hazards and change communities
Earth Science: Natural Disasters: Causes and Effects
How Earth processes create hazards and change communities
Earth Science - Grade 6-8
- 1
Explain how movement along a fault can cause an earthquake.
Think about rocks being stuck, then suddenly breaking or sliding.
An earthquake happens when stress builds up in rocks along a fault and the rocks suddenly slip. The released energy travels as seismic waves and shakes the ground. - 2
A coastal town experiences a strong earthquake under the ocean. Thirty minutes later, a series of large waves reaches the shore. Name the disaster caused by the earthquake and describe one effect it can have.
The earthquake can cause a tsunami. A tsunami can flood coastal areas, damage buildings and roads, and create dangerous fast-moving water. - 3
List two conditions that help a hurricane form over the ocean.
Hurricanes get much of their energy from warm ocean water.
A hurricane forms best over warm ocean water and in air with a lot of moisture. Low wind shear also helps the storm organize and strengthen. - 4
Describe two possible effects of a hurricane on people and the environment.
A hurricane can cause storm surge and flooding that damage homes and roads. It can also knock down trees, erode beaches, and contaminate water supplies. - 5
A river rises above its banks after several days of heavy rain. Identify the natural disaster and explain its main cause.
Focus on what happens when water cannot drain away fast enough.
The natural disaster is a flood. Its main cause is that heavy rainfall added more water to the river than the channel could hold. - 6
Why can cutting down forests on a steep hillside increase the risk of landslides?
Cutting down forests removes roots that help hold soil in place. Without roots, heavy rain can loosen the soil and make it slide downhill more easily. - 7
Compare the causes of a tornado and a hurricane. Include one similarity and one difference.
Think about size and where each storm usually begins.
Both tornadoes and hurricanes are caused by powerful rotating storms. A tornado usually forms from a severe thunderstorm over land, while a hurricane forms over warm ocean water and can be hundreds of miles wide. - 8
A volcano erupts and releases ash into the air. Describe one short-term effect and one long-term effect of the eruption.
A short-term effect is that ash can make breathing difficult, reduce visibility, and damage crops or machines. A long-term effect is that volcanic material can break down into fertile soil over time. - 9
Explain why some earthquakes cause more damage than others, even if they have similar magnitudes.
Magnitude is important, but location and preparation also matter.
Earthquakes with similar magnitudes can cause different damage depending on depth, distance from the epicenter, building design, soil type, and population density. Shallow earthquakes near cities often cause more damage. - 10
During a long period with very little rainfall, crops fail and water levels in reservoirs drop. Identify the disaster and explain one effect on a community.
The disaster is a drought. A drought can reduce drinking water supplies, damage crops, increase food prices, and raise the risk of wildfires. - 11
Explain how drought can increase the chance of a wildfire.
Dry fuel burns more easily than wet fuel.
Drought dries out plants, leaves, and soil. Dry vegetation catches fire more easily and can help flames spread quickly. - 12
A community builds homes on a floodplain near a river. Explain why this location has both benefits and risks.
A floodplain can have flat land and fertile soil, which are useful for farming and building. The risk is that the area is naturally likely to flood when the river overflows. - 13
Describe how an early warning system can reduce the effects of a natural disaster.
Think about what people can do if they know danger is coming.
An early warning system can give people time to evacuate, find shelter, or protect property. It does not stop the disaster, but it can reduce injuries and deaths. - 14
Place these events in the correct cause-and-effect order: loose soil moves downhill, heavy rain soaks a steep slope, a road is blocked by mud and rocks.
The correct order is heavy rain soaks a steep slope, loose soil moves downhill, and a road is blocked by mud and rocks. This sequence describes how a landslide can begin and affect people. - 15
Choose one natural disaster and explain one natural cause, one possible effect, and one way people can prepare for it.
Use this structure: cause, effect, preparation.
Answers will vary. For example, an earthquake can be caused by sudden movement along a fault, can damage buildings and roads, and people can prepare by securing heavy furniture and practicing emergency drills.