In the space of ten days, more than a thousand earthquakes rattled the province of Granada, two of them reaching magnitude 4.8. The seismic sequence that began on 14 August has reignited a question that extends well beyond Andalusia: could Spain be facing a major earthquake?
By 24 August, Spain's National Geographic Institute (IGN) had recorded 1,075 tremors strong enough to be felt by residents. The two largest, both magnitude 4.8, occurred at very shallow depths and were felt in over 500 localities, from Andalusia to parts of Murcia, Castilla-La Mancha, and even the Madrid region.
Spain has a history of far more destructive events. The 1884 Arenas del Rey earthquake, estimated at magnitude 6.5, affected more than 100 towns and killed between 750 and 900 people. In 1954, a magnitude-7.8 quake struck near Dúrcal, but its depth of around 650 kilometres limited surface damage.
So, should Spain brace for another major quake? Raúl Pérez López, an emergency geologist at the Spanish Geological and Mining Institute (IGME-CSIC), told Euronews that earthquakes above magnitude 4 in the south and southeast are not unusual. The region contains faults capable of generating magnitude-5 and, in some cases, magnitude-6 earthquakes.
140 years without a major quake: a ticking clock?
Some recent warnings have focused on the roughly 140 years that have passed since the 1884 disaster. But Pérez López cautions against reading too much into statistical averages. "We can divide the elapsed time by the number of earthquakes and say: every 100 years Spain experiences a major earthquake, because that is what the statistics tell us," he explains. Yet seismic activity does not follow a linear pattern: 200 years might pass without a major event, and then two could strike in quick succession.
"Even though we have gone 140 years without an earthquake, we do not know whether it is going to happen soon or in a long time," he adds. What is certain is that tectonic energy continues to accumulate as the African and Eurasian plates push against each other. The longer the interval, the higher the probability of a major quake—but that does not mean one is imminent.
"There are faults that can trigger earthquakes, but we do not know whether it will be today, tomorrow or in 50 years' time," Pérez López sums up. "We have no way of knowing."
The geologist also warns against the false impression created when earthquakes occur in different parts of the world around the same time. Recent large tremors in various countries might seem connected, but "from a scientific point of view that is not the case."
More than 200 active faults: risk is not confined to Granada
According to Pérez López, IGME has mapped over 200 active faults across Spain. The big unknown is where and when the accumulated energy will be released. "How is that energy going to be distributed or released across all the existing faults? We do not know," he says.
The highest risk is concentrated along the Mediterranean coast, "from Valencia to Cadiz," due to the presence of faults and a history of destructive earthquakes. But significant tremors can also occur in the Pyrenees, the Catalan ranges, and on intraplate faults around Granada and Albacete.
History shows that major Spanish earthquakes are not confined to one province. Torrevieja suffered an estimated magnitude-6.6 quake in 1829, and the 2011 Lorca earthquake, though smaller at magnitude 5.1, killed nine people. These events underscore the need for preparedness across a wide area.
Preventing what we cannot predict
"Our best tool is prevention, without any doubt," says Pérez López. The danger posed by an earthquake depends not only on its magnitude, but also on where it occurs, its depth, and—most critically—how buildings respond. "What kills people in earthquakes is the seismic intensity and the response of buildings," he explains.
Even though predicting the next tremor is impossible, hazard maps allow long-term estimates of how much the ground may shake, enabling building codes to be adapted to the level of risk. The geologist points to recent earthquakes in Venezuela and Colombia as examples of how similar magnitudes can have very different consequences, largely due to building strength.
Predicting earthquakes remains one of science's greatest challenges. Researchers still do not know exactly what determines the moment a fault ruptures, how an earthquake begins, or how the rupture will spread. Pérez López acknowledges the paradox: despite huge scientific and technological advances, we still cannot predict earthquakes. This shows that "nature has a degree of complexity that we do not yet understand."
Artificial intelligence and deep learning might one day help identify patterns that are currently invisible. But Pérez López believes there is a long way to go. More exhaustive monitoring of faults could eventually lead to some form of forecasting. "But for now, we can only prepare."
As Spain continues to experience seismic activity, the message from experts is clear: the threat is real, but the focus should be on resilience rather than prediction. For those in high-risk zones, understanding the risks and ensuring buildings are up to code remains the most effective defence.
