Anastasia Suen - Earthquakes

EARTHQUAKES

Anastasia Suen

The ground shakes suddenly. Its an ! The layers of rock deep inside Earth are on the move. When the Earth shakes below the surface, it can cause major damage above.

The ground below us is always moving. An earthquake can happen at any time of the year. It can happen anywhere. You cant stop an earthquake, but you can learn what to do when one happens near you.

The 1994 Northridge earthquake caused the collapse of this freeway overpass in Los Angeles.

This map shows earthquakes in the United States from 1900 to 2013.

Earthquakes have been recorded all across the United States. Some quakes are small and are barely noticed. Big earthquakes, on the other hand, get everyones attention!

Sixteen people died after the Northridge Meadows apartments collapsed in the 1994 Northridge earthquake.

In 1994, an earthquake in Los Angeles caused apartment buildings to collapse. At the Northridge Meadows apartments, the entire first floor crumpled. The second floor fell down to the ground level. The third floor became the second floor.

Why does the Earth move? Lets take a look inside. The Earth has three layers. The outer layer is the crust. Thats easy to see. Under the crust is the mantle. The mantle has solid rocks and minerals. It also has magma, which is rock that is partly melted. At the center of the Earth is the core. The core of the Earth is made of metal that is extremely hot.

The Earths core is as hot as the Sun!

Fast Fact

Scientists think Earths core is 6,000 degrees Celsius. Thats almost 10,800 degrees Fahrenheit!

You see the Earths crust every day. It is on land and under water. The crust on the land is called the continental crust. The crust under the ocean is called the oceanic crust.

The crust is made up of three types of igneous rocks. The word igneous means they were made with intense heat. Some igneous rocks, such as granite, became solid rock while they were underground. Andesite and basalt became solid rock above ground.

The Earths crust is made of granite, andesite, and basalt.

The first way to look at the inside of the Earth is to talk about the three layers. These three layers tell us what the Earth is made of. They are called compositional layers.

When you talk about earthquakes, you need different labels. You need labels that tell you how things move. How things move is called mechanics.

Fast Fact

The Earth has five mechanical layers. Three are solid and two are not. They alternate like this: solid, not, solid, not, solid.

The center of the Earth, the inner core, is solid. But the next layer is not. The outer core is a molten layer. It is hot liquid rock!

The middle layer, the mesosphere, is another solid layer. The next layer is not. The is a weak layer that changes shape.

The outer layer, the , is solid. This is the layer you can see.

These basalt rocks are a small part of the lithosphere.