Can earthquakes be predicted?

Every year, earthquakes leave behind a trail of enormous destruction, killing thousands of people, and yet we are still far from being able to forecast them. 

The latest quake in southern Türkiye, Syria, Lebanon and Palestine is another stark reminder of how suddenly and unexpectedly they can strike.

Earthquakes are by their very nature a sudden phenomena, and predicting with a precise time range is difficult. In an effort to reduce earthquake damage, scientists have been developing techniques for analysing earthquakes for years.

Through hazard mapping and other methods, scientists can only predict the likelihood of a largescale earthquake and pinpoint its potential epicentre. They cannot however give the exact timeframe.  

Earthquake Myths

Imposters might assert that they can predict earthquakes, however, here are reasons why their claims are at fault.

An earthquake is part of the scientific process and a prediction must involve date and time, location and magnitude. It has nothing to do with clouds, bodily aches and pains, or slugs. Further, non-scientific predictions are so general that they can fit any upcoming earthquake. One such example is the self-proclaimed climatologist who falsely predicted that a significant earthquake along the New Madrid Seismic Zone was expected to strike the St. Louis region. He predicted that it would occur on or around December 3, 1990, setting off a media frenzy in the Missouri hamlet of New Madrid and prompting many residents to stock emergency supplies.

Even if one or more of the pseudoscientists' predicted elements turn out to be vastly different from what actually happened, they nevertheless declare success if an earthquake hits that somewhat resembles their prediction.

When anything occurs that is believed to be a precursor of an earthquake in the near future, predictions (by non-scientists) frequently begin to circulate on social media. The so-called precursor is often a cluster of tiny earthquakes, rising radon levels in the water nearby, strange animal behaviour, increasing magnitudes in moderate-sized events, or a moderate-magnitude event that is uncommon enough to raise the possibility that it is a foreshock.

A true prediction is unfortunately impossible because the majority of these precursors frequently occur without an earthquake following them. Instead, a forecast might be stated using probabilistic terms if there is a scientific basis for it.

Several decades ago, seismic data collected from small-magnitude earthquakes and odd animal behaviour were used in China to predict future tremors. When the main earthquake did in fact occur on  February 4, 1975, in northeast china and caused widespread havoc, many people made the decision to sleep outside of their homes and were therefore spared. However, it is uncommon for this kind of seismic activity to be followed by a significant earthquake; regrettably, most earthquakes have absolutely no precursory events. Hence, there were no warnings before the major Sichuan earthquake in 2008, in China, which killed thousands of people.

Clues from past earthquakes

Earthquake probabilities describe the chance of an earthquake of a particular magnitude occurring within a region over a period of years. 

The earthquake probabilities are estimated in two ways: by studying the history of large earthquakes in a specific area and by the rate at which strain accumulates in the rock.

In order to predict the likelihood of future huge shocks resembling those in the past, scientists examine the frequency of large earthquakes in history. For instance, if a region has suffered four earthquakes of magnitude 7 or larger during 200 years of documented history, and if these shocks occurred randomly in time, then scientists would attribute a 50 percent chance (i.e., it's equally likely to happen as not to happen) to the occurrence of another magnitude 7 or bigger earthquake in the region during the next 50 years.

Another way of estimating the likelihood of future earthquakes is by assessing the rate at which strain builds up.  Like pulling a rubber band too tightly, rocks will break and shift quickly when plate movements increase the pressure in them to a critical degree. Scientists calculate a fault segment's annual strain accumulation, the amount of time since the segment's most recent earthquake, and the amount of strain released during that earthquake to estimate how long it will take for the strain to accumulate to the point where another earthquake occurs. 

Earthquake forecast or probability?

Earthquake forecasts are like probabilities but for shorter time frames and are applied to aftershocks. There are usually less frequent aftershocks that occur after a major earthquake. Since most aftershock sequences have a consistent pattern, it is possible to estimate the likelihood of an aftershock during a specific window of time after an earthquake. These probabilities might be larger than 1-in-30.

The purpose of earthquake predictions is to alert people in advance of potentially dangerous earthquakes so they can respond to the emergency in a way that minimizes damage to property and human lives. And experts concentrate their efforts on long-term mitigation of earthquake dangers and assisting to increase the safety of infrastructure, instead of attempting to make short-term predictions.