1. Rapid Changes to the Earth’s Surface
How Volcanoes, Earthquakes and Landslides Change the Earth

2. Our Changing Earth
Did you know that the surface of the earth is constantly changing? It’s true! Every day, the earth’s surface changes. Sometimes, these changes happen very slowly. Other changes happen rapidly. To understand these rapid changes, you have to know about the earth’s structure.

3. Inside the Earth Scientists believe that the earth has several layers:
The inner core is solid metal and is hotter than the surface of the sun!
The outer core is made of molten iron and nickel, and it is very hot too.
The mantle is the thickest layer of the earth. The mantel is constantly in motion.
The crust is the thinnest layer, and also the only layer humans have ever been to. The crust “floats” on top of the mantle, so it is also continuously moving.

4. The Earth’s Crust
The earth’s crust is broken into large pieces called tectonic plates. These plates are continuously moving. Sometimes, the plates pull apart from each other. They can also rub against each other. Other times, one plate slides under another. These movements are often responsible for creating rapid changes to the earth’s surface.

5. Volcanoes
Volcanoes form in places where molten rock called magma pushes up from the hot inner layers of the earth. Magma and hot gases build up inside the volcano, pushing against the volcano’s walls. Eventually, the pressure becomes too great and the volcano erupts. Most volcanoes are located near the edge of a tectonic plate.

6. Volcanic Eruptions
Volcanoes erupt in many different ways. Some eruptions involve lava flows. Others spew poisonous gases, ash, and rock into the air. Occasionally, an eruption will blow the top of the mountain off. Some volcanoes erupt rapidly while others experience slow, ongoing eruptions. Volcano Video

7. How do volcanoes change the land?
Volcanoes change the land in many ways. They can block roads, burn buildings, and even destroy entire towns. Gaseous eruptions can bury the land in layers of ash and rock. The heat from a volcanic eruption can melt snow causing mudslides and floods. Not all changes are bad! Volcanic eruptions create new land when lava cools and forms rock, and volcanic soil is good for farming!

8. Earthquakes
Most of the time, the earth’s tectonic plates move so slowly that we don’t notice it. But sometimes, the plates jerk suddenly causing the ground to shake violently. This is called an earthquake. Most earthquakes happen near the boundaries of tectonic plates.

9. Measuring Earthquakes
Scientists use a machine called a seismograph to measure earthquakes. Sensors on the ground pick up movement in the earth’s plates. These movements cause the needle on the seismograph to move back and forth. The larger the movements of the needle, the stronger the earthquake. Earthquake Video

10. How do earthquakes change the land?
Earthquakes cause extreme damage to the land. The shaking can destroy buildings, roads, and bridges. Broken gas lines can catch fire and broken water mains can cause floods. Earthquakes that happen underwater can trigger massive tidal waves called tsunamis.

11. Landslides
Landslides occur when a large chunk of ground breaks free from the land and starts to move. Massive amounts of soil, rock, mud and debris move rapidly downhill. Usually, landslides happen where the ground is very steep. Because landslides often happen without warning, they are extremely dangerous.

12. What causes landslides?
Landslides can be caused by many different things. They are very common after natural disasters, such as earthquakes and volcanic eruptions. Flooding or heavy rains can also trigger landslides. Deforestation and building on unstable ground can trigger landslides. Landslide Video

13. How do landslides change the land?
Landslides cause a great deal of damage, but usually in a smaller area than volcanoes or earthquakes. They can wash away roads, trees, cars, and even people. They can also send houses and buildings toppling down hillsides.

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