An earthquake is a sudden shaking of the ground caused by movement of large pieces of Earth's crust called tectonic plates. Earth's outer layer is broken into these huge plates that fit together like a puzzle and are slowly moving. When plates push against each other, pull apart, or slide past each other, stress builds up along their edges. When the stress becomes too great, the rock suddenly shifts, releasing energy as vibrations (seismic waves) that shake the ground. This shaking is what we feel as an earthquake.
Use a hands-on model: push two textbooks against each other on a table until they suddenly slip -- that snap and movement is like an earthquake. Stack blocks on a table and shake the table to demonstrate how buildings respond to earthquakes. Discuss earthquake safety (drop, cover, hold on). Show maps of earthquake zones and compare them to volcano maps -- they overlap because both follow plate boundaries.
The ground beneath your feet feels solid and permanent. But it is actually the surface of huge moving pieces of rock called tectonic plates. These plates make up Earth's outer shell, fitting together like the pieces of a giant jigsaw puzzle. They are always moving -- very slowly, just a few centimeters per year -- but they are moving. And sometimes, that movement causes the ground to shake violently. That shaking is an earthquake.
Here is how it works. Where two plates meet, they are pushing against each other, pulling apart, or sliding past each other. But the edges of the plates are rough, and friction holds them in place. As the plates keep trying to move, stress builds up along the edge -- like bending a stick farther and farther. Eventually, the stress becomes too much. The rock along the plate boundary suddenly snaps and shifts position, releasing all that stored energy at once. The energy travels outward from the break in waves, like ripples from a rock dropped in a pond, shaking everything on the surface.
Small earthquakes happen every day all around the world -- most are so gentle that people do not even feel them. Only instruments called seismographs can detect them. But sometimes a large amount of stress releases at once, causing a major earthquake that shakes buildings, cracks roads, and can cause serious damage. The most dangerous thing about an earthquake is not the ground itself -- it is the shaking that can cause buildings and objects to collapse or fall.
If an earthquake happens while you are indoors, the safest thing to do is Drop, Cover, and Hold On. Drop to the ground so you do not get knocked over. Get under a sturdy table or desk to protect yourself from things falling from above. Hold on to the furniture until the shaking stops. Stay away from windows and tall furniture that could topple. Earthquakes usually last less than a minute, but those seconds of shaking can feel much longer. Being prepared and knowing what to do makes a real difference in staying safe.