The signal before a great earthquake, the French study of fault slip: expert skepticism

Is it possible to predict earthquakes? not yet. However, this issue has been at the center of scientific research for decades, as experts have analyzed data from previous earthquakes in search of signs that could be taken as precursors of an impending shock. And in a new study published in the scientific journal SciencesConducted by two researchers from the French National Center for Scientific Research (Cnrs), Quentin Pelletre and Jean-Mathieu Noquet, it shows how some large earthquakes are preceded by a fault-slip acceleration, which can be found two hours before the seismic event occurs at the surface. The study was conducted by analyzing GPS measurements of more than 90 earthquakes, which occurred all over the world, with a scale equal to or greater than 7. As mentioned earlier, earthquakes cannot be officially predicted, so this is a scientific study that constitutes a step forward towards the search for possible preliminary signals of earthquakes, which can – and the condition is necessary – trigger an early warning and warning system for people.

Doglioni (Ingv): «Useful information from GPS»

Commenting on the study, National Institute of Geophysics and Volcanology (Ingv) President Carlo Doglione explained, “The research also shows how the Earth is constantly sending us signals that we have not yet sufficiently measured, but which in fact can give us key information about the mechanisms of the dynamics of the Earth’s crust and the results open up promising scenarios for real-time forecasting and a great GPS network for prediction. But Professor Doglione is keen to point out that ‘the data is not yet solid enough to say with certainty that fault slip can be considered A reliable initial indication, given that the analysis was found to be consistent for 58 out of 90 aftershocks, and it remains to be seen if it can only be applied to earthquakes of the compressional type, such as those primarily examined in such quakes, or to large-scale earthquakes as well.

Study and expert bafflement

The appearance of fault slip prior to a seismic event in several large earthquakes. In the study by Bletery and Nocquet, GPS data from more than 3,000 monitoring stations located around the world were analyzed, in order to measure fault displacements up to two hours before the seismic event recorded on Earth. Statistical analysis of the data revealed a signal consistent with a period of fault slip acceleration near the epicenter, beginning about 2 hours before the rupture. However, this aspect must be taken with the necessary measures, before starting to develop alarm systems that focus exclusively on these elements. It certainly represents a step forward, but as geophysicist Roland Borgmann of the University of California, Berkeley, points out, “It is not clear whether slow slip accelerations along the fault are clearly associated with large earthquakes or whether they can be measured for individual events with the precision necessary to give a useful warning signal.”

Cover photo: Ansa | Aerial photo of the center of Kahramanmaras in southeastern Turkey after the 7.8-magnitude earthquake hit southern Turkey and northern Syria

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