Why do some earthquakes produce aftershocks?
Quick Answer
After the main rupture, the crust around the fault adjusts to the new stress pattern. Those readjustments can trigger smaller earthquakes for days, months, or even years.
The Full Story
After a major earthquake, the crust does not instantly settle into a stable shape. Stress is redistributed around the ruptured fault, and nearby rocks may fail in smaller slips called aftershocks. The largest aftershocks often happen soon after the main shock, and then their frequency usually declines over time. This pattern was described mathematically by Omori’s law, named after Japanese seismologist Fusakichi Omori, who published it in 1894. Aftershocks can be dangerous because they strike already weakened buildings and slopes.
Key Facts
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