Super Simple Earthquake Projects: Science Activities for Future Seismologists
4 WHAT IS AN EARTHQUAKE An earthquake is when the ground shakes It begins deep beneath Earth's surface An earthquake can cause a lot of damage There is sometimes a sequence of three earthquake stages FORESHOCKS The first stage is foreshocks These are small quakes that occur before a larger one But a quake isn't called a foreshock until a larger one happens after it EARTHQUAKE DAMAGE
5 MAIN SHOCK The second stage is the main shock It is larger than any of its foreshocks The main shock can be very dangerous It can cause large structures to fall down AFTERSHOCKS The third stage is aftershocks These are smaller quakes that follow the main shock Aftershocks can happen weeks or months after the main shock Some continue for years EPICENTER An earthquake starts in one area This is called the epicenter The earthquake is strongest at the epicenter The quake gets weaker as it moves away from the epicenter EARTHQUAKE WEAKENS WITH DISTANCE EPICENTER
6 WHAT CAUSES EARTHQUAKES Earth's crust is made up of pieces called tectonic plates Tectonic plates move slowly This movement causes earthquakes The plates move three different ways This creates three types of boundaries between the plates CONVERGENT BOUNDARY Some plates move toward each other They press together One plate may slide under the other plate This can cause mountains to form The Cascade Range in western North America was formed this way
7 DIVERGENT BOUNDARY Some plates move away from each other The space between the plates is called a rift Magma may rise from under Earth's crust to fill the space Some rifts get filled with ocean water TRANSFORM BOUNDARY Some plates move sideways They grind against each other The San Andreas Fault in California is an example of this type of movement Earthquakes are common there
