For decades, seismic science has operated under an indisputable premise: The less time that has elapsed since the last major earthquake, the lower the probability of another similar one occurring. However, an international research project led by the scholar Matías Carvajal, from the Institute of Geography of the University, just questioned this paradigm.
The study proposes that the Earth’s crust and the underlying mantle do not act as a simple “elastic rubber” where the available energy for the next earthquake is proportionally accumulated with the passing of time. In turn, the earth’s material would act as a memory foam, causing energy to accumulate in an accelerated way during the first decades after a major earthquake.
The discovery - recently published in the prestigious Science Advances journal with the collaboration of researchers from Chile and Canada - redefines the way in which global seismic risk must be evaluated and calls to rethink how the seismic threat is monitored in Chile.
The enigma of the 73 years in Russia
The starting point for the research project was an event that defied traditional seismology logic in the Kamchatka, Russia peninsula. In 1952, the area suffered a mega-earthquake of 9.0 magnitude - the fifth greatest earthquake registered in global history - In 2025, only 73 years later, the same region was shaken with a new event of similar magnitude.
“Since the plates in that area move about 8 centimeters per year, in 73 years they would only accumulate about 6 meters of relative movement. This was insufficient to generate a major earthquake; the scientific community estimated a recurrence interval of between 150 and 200 years. Therefore, at least seven decades were expected to go by before a similar event happened”, Matías Carvajal, principal author of the study, explained.
The first hypothesis of the scientific community suggested that the new earthquake had broken an adjacent or “straggler” segment of the fault, adjusting to conventional models. However, researchers decided to verify if they were indeed different areas.
The hidden key in the Pacific tide gauges
To contrast both rupture areas, the team faced a technical problem: the seismological evidence of 1952 was scarce and inaccurate due to the technological limitations at the time. However, they found the evidence in the sea.
Dozens of analog tide gauges distributed throughout different ports in the world had registered the 1952 tsunami with great precision. When performing a quantitative comparison of tide records in 1952 and 2025 of the same stations throughout the Pacific Ocean, scientists discovered that both tsunamis were practically identical.
Through advanced numeric modeling, researchers confirmed that both earthquakes had broken essentially the same section of the fault, calling into question the theory that centuries were needed to accumulate equivalent energy.
The viscoelastic mantle: the missing piece
The limitation of the traditional models lies on the assumption that the earth’s material in the subduction areas is only deformed in an elastic way. Despite the earth’s crust (the superficial layer) possessing elastic properties, the mantle underneath is viscoelastic (combines the rigidity of a solid with the slow fluidity of a dense liquid).
“By integrating viscoelasticity in the energy accumulation models, we discovered that the system is not charged proportionally with the passing of time, but it does it in an accelerated way in the decades immediately after the earthquake”, Carvajal noted. This accelerated re-charge implied that the fault recovers its rupture ability faster that what was believed in the period immediately after a mega-earthquake.
What does this paradigm mean for Chile?
Chile has historically focused their vigilance on the great seismic gaps that have been accumulating tension for centuries without registering a major event, such as: The Norte Grande (Iquique - Mejillones), without a major earthquake of this kind since 1877; The Norte Chico (Coquimbo - Taltal), with its latest significant event in 1922 (a century ago); and the Central Zone (Metropolitan and Valparaíso), whose last mega-earthquake happened in 1730 (almost 300 years ago). In the rest of the country, major recent earthquakes suggested that the next one would take many more decades to happen.
However, the results of this study require that we expand our view to other regions such as the south area, which was hit by the historical earthquake of Valdivia in 1860 (9.5 magnitude).
“What occurred in Russia stops being a theoretical hypothesis and becomes a real warning: recurrence periods between major earthquakes can reduce drastically in relation to what we thought. A new great earthquake in the south of Chile would not be an inexplicable surprise, but a scientifically understandable phenomenon under this new paradigm”, Carvajal concluded.
By Pablo Díaz
Strategic Communications Department
