Can a super earthquake be predicted?



by LORENZO CIOTTI

Can a super earthquake be predicted?
© Buddhika Weerasinghe / Stringer Getty Images News

The disastrous earthquake that struck central Japan on January 1, 2024 reopened the question: can super earthquakes be predicted? Some earthquakes, especially the strongest, are accompanied, preceded or followed by seismic precursors such as telluric lights, sudden variations in the magnetic, electric field or local radioactivity.

All these manifestations have been confirmed in observations and testimonies and have been studied and partly confirmed by scientific research which has led to the explanation of each of them, even if, in the absence of unanimous consensus, they do not in fact constitute measures actually recognized and adopted on the forecasting front.

Is it posisble to predict an earthquake?

The Haicheng earthquake of 4 February 1975 was historically the first and only earthquake predicted with these techniques, but in that case the seismic precursors of a geological nature were so intense and regularly progressive that they left no doubt about the proximity and imminence of the event.

Even the monitoring of any seismic swarm before a mainshock often does not seem to lead to concrete results in terms of prediction as the vast majority of seismic swarms evolve without producing catastrophes or dissipating more or less slowly over time according to Omori's law.

Currently, some experimental physical seismic prediction models of a statistical nature have proven to be quite effective in predicting some aftershock sequences, but quite disappointing in predicting the main shock.

Japan earthquake© Tomohiro Ohsumi / Stringer Getty Images News

At the current stage of seismological research, the most concrete results for predicting earthquakes are therefore obtained statistically in the long term, i.e.

by consulting hazard maps that take into account the return times of an earthquake in a given territory, i.e. by calculating the probability of its occurrence. . However, the time interval in which the occurrence of an earthquake is considered probable is quite long, even tens of years, making any reasonable attempt at prevention that makes the evacuation of populations effective in vain.

In the hope of being able to create a short-term and reliable earthquake forecasting system, various studies are underway; for this research a network of radon detectors is used, appropriately distributed on the surface of the affected areas.