Earthquake The ground shakes suddenly It’s an earthquake 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 can’t 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 4
US Earthquakes 1900 2013 Magnitude 3 5 5 0 5 0 5 5 5 5 6 0 6 0 Depth 0 69 km 70 299 km 300 700 km Alaska Hawaii Puerto Rico 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 everyone’s attention 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 Sixteen people died after the Northridge Meadows apartments collapsed in the 1994 Northridge earthquake 5
Why does the Earth move Let’s take a look inside The Earth has three layers The outer layer is the crust That’s 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 Earth’s core is as hot as the Sun crust mantle Fast Fact Scientists think Earth’s core is 6,000 degrees Celsius That’s almost 10,800 degrees Fahrenheit 6 outer core inner core
You see the Earth’s 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 granite basalt andesite continental oceanic crust granite andesite and basalt mantle peridotite The Earth’s crust is made of granite andesite and basalt 7
