What is the study of earthquakes called?
Quick answer
The scientific study of earthquakes is called seismology, from the Greek seismos, meaning “shaking.” Scientists who study earthquakes are seismologists. They use instruments called seismometers to record ground movements and learn about earthquakes and Earth’s interior.
Why earthquakes happen
Earth’s outer shell is broken into tectonic plates that slowly move. Along faults, plates get stuck, and stress builds up. When the rock suddenly slips, energy is released as seismic waves, shaking the ground. Most earthquakes occur along plate boundaries, such as the Pacific “Ring of Fire.”
Types of seismic waves
| Wave | Speed | Notes |
|---|---|---|
| P-waves (primary) | Fastest | Push and pull the ground; travel through solids and liquids |
| S-waves (secondary) | Slower | Shake side to side; only travel through solids |
| Surface waves | Slowest | Cause most of the damage |
Because S-waves can’t travel through liquid, seismologists discovered that Earth’s outer core is liquid.
How earthquakes are measured
| Measure | What it tells you |
|---|---|
| Magnitude (moment magnitude, Mw) | The energy released. Each whole number is about 32 times more energy |
| Intensity (e.g. Modified Mercalli) | How strongly the shaking was felt and the damage in a particular place |
The old Richter scale (1935) has largely been replaced by the moment magnitude scale for large quakes.
The largest earthquakes recorded
| Earthquake | Year | Magnitude |
|---|---|---|
| Valdivia, Chile | 1960 | 9.5 (the largest ever recorded) |
| Alaska, USA | 1964 | 9.2 |
| Sumatra, Indonesia | 2004 | 9.1 |
| Tōhoku, Japan | 2011 | 9.0–9.1 |
In February 2023, two powerful earthquakes of about 7.8 and 7.5 struck southern Turkey and northern Syria, among the deadliest in modern history.
Can earthquakes be predicted?
Not precisely. Seismologists can estimate where large earthquakes are likely over decades, and early-warning systems can give seconds of warning before strong shaking arrives.
The movement of plates also shaped Pangaea and the Mariana Trench.
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