1. Dormant destruction
Globally, we detect over 200,000 earthquakes each year but no doubt millions more take place. Most earthquakes are tiny, causing very little damage and posing no risk to most people. But some can be devastating, with the power to wreak billions of pounds worth of damage, destroy homes and kill.
Scientists have known where earthquakes are likely to strike for years. But predicting when they're going to happen, and their magnitude, is proving a lot more difficult.
2. CLICKABLE: Disaster without warning
Click or tap on the hand icon and then select the labels to find out more about the deadliest earthquakes in history and why they happened where they did.
This content uses functionality that is not supported by your current browser. Consider upgrading your browser.
Data: US Geological Survey; Image: SPL
3. Shaky forecasts
So if we know the likely location of earthquakes, why are they so difficult to predict?
For predictions to be useful – to evacuate affected areas – they must be highly accurate. Scientists have tried using indicators like radon gas emissions, electromagnetic variations and even animal behaviour to build prediction models. But attempting to pinpoint the precise moment when the tectonic plates will release the tremendous energy, which drives earthquakes, has been elusive.
In 1974, seismologists issued an earthquake prediction for the Haicheng region of China. On 4 February 1975, residents were evacuated before a major earthquake of magnitude 7.3 struck, seemingly validating the scientists’ prediction. But the timing forecast was approximate so that an earthquake could occur at any moment in a large window. Many experts claim it was the foreshocks preceding the earthquake which triggered the evacuation rather than the prediction.
Millions of harmless earthquakes happen across the globe every year so, even if we could predict an earthquake, it would be useless without knowing its magnitude. Scientists are also struggling to differentiate minor tremors from major disasters.
Earthquakes stop when the energy stored in the plates has been dissipated – when the friction arresting the moving plates and rock is greater than the energy driving them forward. All earthquakes begin with small tremors but experts don’t yet understand why some suddenly stop and others continue. There are many geological processes involved and colossal varying forces, making prediction currently impossible.
4. Should we concentrate less on prediction?
Should we admit defeat and focus on reducing the damage caused by inevitable earthquakes?