The earth is made of three layers: the core is the innermost layer, the mantle is the middle layer and the crust is the outermost layer. The upper mantle and the crust are collectively known as the lithosphere. The lithosphere is not one large piece. It is broken into approximately 12 pieces, known as plates, which move slowly over the surface of the Earth. Sometimes, the plates become locked together and energy builds. When the plates finally break free from one another, it causes the ground to shake. This is an earthquake.
When and Where Do Earthquakes Occur?
Earthquakes are unpredictable and occur without warning. Approximately 90% of earthquakes occur at a plate boundary, the place where two or more plates meet. Forty-one U.S. states and territories, in all regions, are at a moderate to high risk of earthquakes.
What Are the Consequences of an Earthquake?
Property damage can be great after an earthquake. The shaking causes objects to fall, buildings to become unstable and collapse, and roads to become impassable. Damage to gas, water and electrical lines are hazards that can cause secondary disasters such as fires, tsunamis (large ocean waves), floods, electrocutions, landslides and explosions.
Falling objects, dangerous debris, drowning, landslides, fires and building collapses can cause injuries and deaths. Additionally, diseases can spread quickly from contaminated food and water or unsanitary conditions caused by flooding and water and sewage system damage.
Resources for Earthquakes