"Common Natural Disasters and Their Causes" Causes and Prevention of Common Natural Disasters PPT (Lesson 1)

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"Common Natural Disasters and Their Causes" Causes and Prevention of Common Natural Disasters PPT (Lesson 1)

Part One: Strengthening the Implementation of Basic Knowledge

[Self-reading textbook·Fill in key points]

1. Natural disasters

1. Concept: Refers to events or phenomena that are mainly caused by abnormal changes in _____ and cause harm to human _____ and the living environment.

2. forming conditions

(1) There must be __________ as an inducement;

(2) There must be damaged persons, property, resources, etc. as _____ to withstand the disaster.

3. Classification: Based on the classification of the causes of natural disasters, and according to the characteristics of the disaster and the different disaster management and disaster reduction systems, they are divided into seven categories: earthquake disasters, _____ disasters, meteorological disasters, flood disasters, _____ disasters, and agricultural and forestry disasters.

2. Earthquake disasters and geological disasters

1. earthquake

(1) Concept: _____ accumulated over a long period of time in the earth's crust spreads in the form of _____ and causes ground vibrations, forming earthquakes.

(2) Distribution: Earthquakes are concentrated in the _____ seismic zone and the Mediterranean-Himalayan seismic zone.

(3) Characteristics: The occurrence range is _____, the frequency is high, the intensity is high, and the hazards are _____.

(4)Hazard

2. landslides and mudslides

3. Meteorological disasters and floods

1. Concept: Disasters caused by _____ or climate anomalies.

2. drought

(1) Concept: Precipitation is significantly lower than the multi-year average level, and there is insufficient _____, which cannot meet the needs of _____ and pasture growth, resulting in greater disasters such as reduced yields or no harvests.

(2) Harm: Not only will it cause _____ disasters, but it will also seriously affect industrial production, urban water supply and the ecological environment.

(3) Distribution: The inland areas of Africa, Asia and Oceania are areas with a higher frequency of droughts in the world, and _____ is the area with the most severe droughts.

(4) Characteristics of drought in my country: scope _____, longest duration, and greatest impact on agricultural production.

(5) Drought-prone centers in my country: _____, South China, Southwest and Jianghuai regions.

3. typhoon

(1) Concept: refers to the tropical _____ with the maximum average wind near the center reaching level 12 and above in the vast low-latitude ocean of the northwest Pacific.

(2)Influence

(3) Areas affected by typhoons in my country: Mainly concentrated in the eastern coastal areas, among which the coastal areas of Hainan, Guangdong, Fujian, Taiwan, and Zhejiang are the most serious, followed by Jiangsu and Guangxi.

4. Floods

(1) Concept: floods and waterlogging. Floods refer to those caused by heavy rain or melting snow.

the disaster caused. Waterlogging includes waterlogging and waterlogging. Waterlogging refers to the disaster of flooding farmland due to _____, resulting in reduced crop production or even no harvest; waterlogging refers to the disaster caused by excessive rainfall, low-lying terrain, and stagnant water that cannot be removed in time.

(2) Characteristics: Damage area _____, heavy losses.

(3)Distribution

(4) Characteristics of flood disasters in my country

① It is one of the natural disasters that occurs frequently in my country, has a wide range of hazards, and causes the most serious losses;

②With the growth of population, economic development and increase of social wealth, losses caused by flood disasters continue to _____.

Common natural disasters and their causes PPT, part 2: Pay attention to problem-based teaching

Question 1: What is the formation process of earthquakes and their hazards? Important and difficult test points

[Thinking and exploring]

The 1976 Tangshan earthquake and the 2008 Wenchuan earthquake were the two most serious earthquake disasters in my country in the past 70 years. Although the magnitude and intensity of the two earthquakes were similar, the losses caused by the two earthquakes were very different. The death toll of the Wenchuan earthquake was far less than that of the Tangshan earthquake, but the direct economic losses were far greater than that of the Tangshan earthquake.

[Problem Design]

1. Use "comprehensive thinking" to analyze how earthquakes are formed?

Tip: Rock layers in the earth's crust will tilt or bend under the long-term action of geostress. When the accumulated geostress exceeds the limit that the rock layer can withstand, the rock layer will suddenly break or dislocate, causing the energy accumulated over a long period of time to be released rapidly and spread around in the form of seismic waves, causing the ground to vibrate. Create an earthquake.

2. What are the influencing factors of earthquake intensity using "comprehensive thinking" to analyze?

Tips: Magnitude, focal depth, epicentral distance, geological structure, ground buildings, etc.

3. Based on "geographical practice", what do you think is the difference in losses between the two earthquake disasters in the material? What's the main reason?

Tip: The death toll in the Wenchuan earthquake was less than that in the Tangshan earthquake, which shows that people's earthquake prevention and disaster reduction capabilities have improved; the economic losses in the Wenchuan earthquake were greater than those in the Tangshan earthquake, which shows that with economic development, economic density has increased.

[Training to pass the test]

1. Which of the following statements about earthquakes is correct ()

A. Some earthquakes are caused by tectonic movements

B． Earthquakes, no matter how big or small, are destructive

C. Earthquakes are a natural phenomenon and have nothing to do with human activities

D. An earthquake has multiple magnitudes

According to the China Seismological Network, at 4:27 on April 28, 2019, Beijing time, an earthquake measuring 4.8 on the Richter scale occurred in Sunan County, Zhangye City, Gansu Province (39.19 degrees north latitude, 97.45 degrees east longitude), with a focal depth of 10 km. When it happened, obvious earthquakes were felt in Yumen, Jiuquan, Jiayuguan and other places. Answer questions 2 to 3 accordingly.

2. The epicenter of this earthquake occurred in ()

A. Earth's core B. upper mantle

C. Asthenosphere D. crust

3. earthquake disaster()

A. Mainly occurs in ocean edge areas

B． It will cause huge losses of human life and property and is the most serious geological disaster.

C. It is purely a natural phenomenon and has nothing to do with human activities.

D. Nothing to do with volcanic eruptions

4. Places a and b are 300 km and 200 km from place c respectively. When an earthquake occurs 15 km underground in c, the possible phenomenon is ()

① The intensities in places a and b are different. ② The intensities in places a and b are the same. ③ Residents in place c will feel horizontal shaking first, and then bumping up and down. ④ When the seismic wave reaches place a, the direction is perpendicular to the ground.

A. ①② B. ②④

C. ①④ D. ②③

Analysis: An earthquake has only one magnitude, but the intensity of earthquakes in different areas may be different or the same, so ①② are both correct. Since the propagation speed of longitudinal waves is fast, it causes the ground to vibrate up and down, and the propagation speed of transverse waves is slower than that of longitudinal waves. Therefore, residents in land c will feel bumps up and down first, and then shake horizontally, so ③ is wrong. Since the seismic wave is a kind of elastic wave, it can propagate in all directions from different directions. Therefore, when the seismic wave reaches ground a, its direction can be perpendicular to the ground or oblique to the ground, so ④ is wrong.

Question 2: What are the conditions for landslides and debris flows to occur? Basic test points

[Thinking and exploring]

In early July 2018, rainfall reached record highs in many places in western and central Japan. The western part of Japan suffered the worst heavy rain disaster since July 1983. Continuous heavy rains caused river water levels to surge and rivers to burst their banks, triggering landslides, mudslides and other disasters. 223 people died, 17 people were missing, more than 2,000 houses were damaged, and transportation and communications were affected.

[Exploration 1] What are the similarities between landslides and debris flow disasters?

Tip: Sudden; mainly occurs in mountainous areas; highly destructive; mainly formed by gravity.

[Exploration 2] What are the hazards caused by landslides and debris flows?

Tip: Landslides can bury houses and cause casualties to humans and animals; destroy towns, factories and mines; damage railways, highways, and waterways, threaten traffic safety; and destroy surface coverage, etc. Mudslides often cause devastating disasters to local villages, towns, roads, buildings and mines. Both can cause heavy casualties.

Common natural disasters and their causes PPT, the third part: developing structural thinking

Cold wave is a kind of disastrous weather, which will cause severe cooling, strong winds and snowstorms along the way. Disasters such as strong winds, frost, snowstorms, rain squalls and other disasters caused by the cold wave have a great impact on agriculture, transportation, electricity, navigation and people's health. Great impact. At 18:00 on December 24, 2018, the Central Meteorological Observatory issued a cold wave blue warning. This cold wave is fierce, affecting more than 20 provinces and cities in my country, and the temperature across the country generally drops between 6 and 10 degrees Celsius. Is the cold wave doing all the harm and no good?

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Update Time: 2024-11-17

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