🔬 ScienceGrade 4Lesson 13
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Natural Disasters Study
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Learning Objectives
- 1Describe the causes and effects of major natural disasters
- 2Classify events as earthquakes, volcanoes, hurricanes, or floods
- 3Explain how humans prepare for and respond to natural disasters
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Mini Lesson
A natural disaster is a major event caused by natural processes that causes widespread damage or loss of life. Understanding what causes each type of disaster helps communities prepare and respond effectively.
Earthquake
- Caused by the movement of tectonic plates along fault lines beneath Earth's surface.
- Measured on the Richter scale — higher numbers mean stronger shaking.
- Can trigger secondary disasters such as tsunamis and landslides.
Volcano
- Caused by magma (molten rock) erupting through a weak point in Earth's crust.
- Releases lava, ash clouds, and toxic gases.
- Can alter local climate and destroy habitats over large areas.
Hurricane
- A large tropical storm with rotating winds exceeding 119 km/h.
- Forms over warm ocean water — the heat and moisture fuel the storm.
- Causes flooding, destructive winds, and storm surges along coastlines.
Flood
- Caused by heavy rainfall, storm surges, or rivers overflowing their banks.
- Can damage roads, buildings, and farmland, and displace large populations.
- Flash floods develop quickly and are especially dangerous.
Disaster Preparedness
- Early warning systems alert communities before a disaster strikes.
- Evacuation plans help people move to safety quickly.
- Building codes ensure structures can withstand earthquakes or high winds.
- Emergency supply kits (water, food, first aid) support survival after a disaster.
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Tip: remember the primary cause for each disaster — tectonic plates (earthquake), magma (volcano), warm ocean (hurricane), heavy rain (flood).
Vocabulary
tectonic plates
Large sections of Earth's crust that move slowly and can cause earthquakes when they collide or slide.
magma
Molten rock beneath Earth's surface; called lava once it erupts.
Richter scale
A scale used to measure the strength of an earthquake.
tsunami
A series of large ocean waves triggered by an underwater earthquake or eruption.
storm surge
An abnormal rise in sea level driven by a hurricane, causing coastal flooding.
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