Презентация " Природные катастрофы - землетрясения"

  Earthquakes

• An earthquake is one of the worst natural disasters on our earth. We think that the ground we stand on is very stable, but it isn't. It moves quite a lot. In the last few decades scientists have been able to find out why earthquakes happen.
• Earthquakes happen when there is a sudden vibration in the earth's crust. It's like a large lorry that travels down your street. When it passes by, you feel your house shake.
• Earthquakes can be caused by a lot of things:
• •   Volcanoes that suddenly erupt •  Meteorites that hit the earth •  Undergrounds explosions •  Buildings that fall apart

• In the middle of the 20th century scientists found out that continents do not always stay in the same place. They have been moving on plates for millions of years. The earth's surface is made up of many such plates. Where two plates meet magma comes out of the inner part of the earth. These areas are called faults—breaks in the earth's crust.

• Earthquakes occur all over the world but there are places where they happen more often. Big earthquakes can be found where plates meet.
• 80% of the world's earthquakes happen around the Pacific Ocean—near the east coast of Asia and the west coast of America. Japan has over 2,000 earthquakes every year and California and South America are also very active earthquake zones. The edge of the Pacific Ocean is also called the "Ring of Fire" because there are also many active volcanoes in this region.

• Effects of earthquakes
• Earthquakes make the ground move. Buildings shake and many of them collapse. Landslides also happen when rocks get loose.
• Another danger is fire. In 1906 San Francisco was hit by a big earthquake and many houses burned down because they were made of wood.
• When an earthquake occurs on the sea floor, big waves - called tsunamis - hit the coast. They often come without any warning and they kill many people and destroy buildings and streets near the coast.
• Earthquakes also can lead to diseases, especially in developing countries. When water supplies are destroyed people don't have safe water to drink. Sometimes earthquakes also hit hospitals where injured people are treated.

• We understand earthquakes a lot better today than we did 50 years ago, but we still can't do very much about them. They are so powerful, that we cannot control them.
• Scientists can tell us in which regions earthquakes will probably happen, but they can't tell us exactly where.
• So what can we do about earthquakes? We can make our houses we live in and buildings we work in safer. Today architects use materials that won't collapse when an earthquake hits—like steel and concrete

• The biggest earthquakes in history
• 856
• 200,000 people are killed in one of the deadliest earthquakes in history in Damghan, Iran.
• 1138
• An earthquake in Aleppo, Syria kills 230,000
• 1556
• The deadliest earthquake in history hits Shensi province in China. Almost 1 million people are killed.
• 1755
• The most serious earthquake in Europe hits Lisbon, Portugal. The whole city is destroyed. About 70,000 people get killed.
• 1906
• The city of San Francisco is hit by a large earthquake. A big fire destroys most of the city. About 500 people die.
• 1908
• Messina, Sicily is totally destroyed by a large earthquake. About 70,000 people are killed.
• 1923
• Tokyo, Japan is destroyed by an earthquake with a magnitude of 8.3. 150,000 people are killed.
• 1960
• The strongest earthquake ever recorded hits Chile. It reaches 9.5 on the Richter scale. 20,000 people die.
• 1964
• The strongest earthquake in North America hits Anchorage Alaska. Ocean waves reach a height of 20 metres. 200 people are killed.
• 1976
• The biggest earthquake ever recorded in China leaves 242,000 people dead.