Earthquakes 101 | National Geographic

When the ground starts to quiver, glasses rattle, walls shift, and suddenly, everything begins to collapse. These telltale signs can signal the onset of a devastating earthquake. We've all seen the destruction they unleash, and many of us have even lived through one — we know they can be deadly. But where does this mountain-moving force come from?

While we may think we’re standing on solid ground, the truth is, the earth beneath us isn't stable at all. Our planet's crust is composed of about 12 major tectonic plates, fitting together like a gigantic jigsaw puzzle. These huge slabs of land float on superheated magma and are in constant motion, bumping and grinding against one another. It’s along these seams where earthquakes tend to happen.

The Science Behind Earthquakes

When friction between two tectonic plates becomes violent enough, seismic shock waves ripple through the ground, rattling everything in their path. The stronger and shallower the quake, the more violent the destruction. One of the most violent types of earthquakes is born in a subduction zone, where one tectonic plate is shoved beneath another. As one plate is forced downward into the mantle, the other juts upward, often with catastrophic results.

This is the kind of quake that rocked Nepal in May 2015. And when subduction occurs beneath the ocean, it can generate giant, unstoppable waves known as tsunamis, like those that tragically claimed hundreds of thousands of lives in Japan and Indonesia.

Statistics that Shock

On average, earthquakes kill about 10,000 people each year, though sometimes that number can soar much higher. The 2010 earthquake in Haiti took more than 300,000 lives, making it one of the deadliest on record. It is estimated that there are about 500,000 detectable earthquakes globally each year, with approximately 100,000 of these being felt, and around 100 causing damage.

The Richter Scale: Measuring Earthquakes

The magnitude of an earthquake is measured using the Richter Scale, which runs from 0 to 10, with 10 being the strongest. Each whole number increase on the scale represents a tenfold increase in ground motion. Interestingly, in recorded history, the world has never experienced a magnitude 10 on the Richter scale. However, scientists predict that we could see at least one major quake of magnitude 8 or higher every year.

The fact is, the Earth’s crust is restless and always on the move. While we can’t see earthquakes coming, we can prepare for them. Engineers are now designing stronger buildings that can withstand direct hits. Scientists are analyzing data to project the power of future quakes and anticipate when and where they may strike next.

Looking Ahead

Currently, we can only estimate the probability of an earthquake occurring, but there’s hope on the horizon. One day, we may learn to predict these natural disasters, minimizing their destruction and saving countless lives.