Recent Surge in Earthquake Activity
In recent months, a series of significant earthquakes have struck across the globe in quick succession. On June 24, Venezuela experienced two seismic events measuring 7.2 and 7.5 on the Richter scale, occurring just 39 seconds apart. Little more than a month later, a 7.1 magnitude earthquake shook the Kumamoto region of Japan.
The focus returned to Latin America on August 10, when a 7.4 magnitude quake hit Colombia, causing extensive damage in several cities and marking the strongest tremor recorded in the country over the past decade. Then, on August 20, a 7.2 magnitude earthquake was registered 35 kilometres north of Coracora in Peru. Viewed in isolation, these occurrences may foster an unsettling perception: are we truly experiencing more earthquakes?
Dr. Iván Granados Chavarría, a seismologist and researcher at the Seismology Department of the National Autonomous University of Mexico (UNAM), suggests that while there may be a widespread perception of increased seismic activity, it is essential to remember that the Earth is a dynamic system in constant motion. According to him, the occurrence of several significant earthquakes in a relatively short timeframe does not necessarily signify an abnormal spike in seismic activity. “We are within the normal range of seismicity for this magnitude, and its occurrence is merely coincidental,” he explains.
Long-term records support this perspective. The United States Geological Survey estimates that, on average, around 16 earthquakes of magnitude 7 or greater occur globally each year since 1900. While some years see figures exceed this average, others fall short, without indicating a fundamental change in global seismic activity.
The Complexity of Measuring Seismic Activity
Determining whether earthquakes are indeed becoming more frequent is more complex than merely comparing the number of seismic events year on year. The quantity recorded in historical catalogues is also influenced by the technology available to detect them.
Granados highlights the existence of both global and local seismic networks, although their coverage varies significantly across different regions. Countries situated in tectonically active areas such as Japan, Chile, or Mexico have developed extensive monitoring networks, while other regions may have fewer sensors, leading to fewer recorded minor tremors. “If we have an area that perhaps does not experience frequent quakes but lacks a seismic sensor, we cannot accurately assess the actual rate of seismicity occurring there,” he states. “The more sensors we have, the better analysis and study we can conduct regarding this type of seismicity.”
Mexico exemplifies how technological advancements can significantly alter seismic records. The National Seismological Service recorded just 796 earthquakes in 1990, while in 2025, the figure soared to 40,256. This stark difference does not imply that the country is experiencing earthquakes dozens of times more frequently. Granados notes that earlier stations relied on analogue instruments, whereas modern networks are equipped with digital technology and greater coverage, allowing for the detection of smaller tremors that may have previously gone unnoticed.
Historical Context and Technological Advances
When comparing present-day seismic activity with that of centuries past, another challenge arises. To study earthquakes that occurred before the advent of modern instruments, researchers must rely on historical documents and accounts of their effects.
A review of significant earthquakes in Mexico published in 2021 cautions that estimates of magnitude and location for these ancient events can be uncertain, as they are reconstructed based on their impact on populations that were much smaller at the time.
The role of the internet and social media has also transformed how we perceive seismic occurrences. Today, a simple phone search can yield videos, maps, alerts, and eyewitness accounts of an earthquake that took place thousands of miles away. Granados asserts that this constant flow of information can alter our perception of earthquake frequency.
The difference now is that these movements compete for our attention in real-time. A sequence of major earthquakes may prompt individuals to receive and acknowledge information about other events that they might not have actively sought out. Additionally, the introduction of earthquake alerts on smartphones and other early warning systems has further influenced public perception. However, Granados emphasises that these technologies do not predict earthquakes; they function to alert populations that have not yet been affected by the strongest waves once the event has already commenced.
Understanding Earthquake Triggers
The recent spate of earthquakes has raised another intriguing question: if a significant quake occurs in one country and another follows shortly after thousands of kilometres away, could the first have triggered the second? Granados indicates that there is no evidence to support a connection between temporally close events like those in Venezuela, Japan, and Colombia. The tectonic contexts of these regions differ, and mere coincidence does not establish a link between them.
“When an earthquake occurs in a certain area, the energy travels worldwide,” he explains. As these waves traverse vast distances, much of that energy dissipates. To connect two seismic events, more than just noting their occurrence within the same day or week is required.
There is, however, an important nuance. Seismological research has documented a phenomenon known as dynamic stress transfer or activation, where the waves from a significant earthquake can trigger seismic activity at great distances, particularly in areas already prone to seismicity. Nevertheless, this does not mean that recent large earthquakes are part of a global chain reaction. Establishing a relationship requires studying the faults, seismic waves, and changes observed in each region, as two events occurring mere hours or days apart is insufficient to establish a connection.
Events are different when they occur within the same area and form part of the same process. Granados cites the example of Venezuela, where two earthquakes were recorded approximately 39 seconds apart. In this instance, it was a seismic doublet, meaning two closely timed and located movements associated with the same tectonic zone. Aftershocks, which are earthquakes occurring after a main event in the same region, also demonstrate a relationship between movements. “The larger the earthquake, the greater the number of aftershocks,” Granados explains. In these cases, a connection between movements is indeed evident.
Seasonal Perceptions of Seismic Activity
In Mexico, the discussion of seismic coincidences inevitably leads to September. The earthquakes that struck in this month in 1985, 2017, 2021, and 2022 have reinforced the belief that there exists a particularly seismic-prone season. Granados contends that this perception is heavily influenced by experiences specific to Mexico City.
“It’s a somewhat chilangocentrist perception,” he remarks, as in coastal regions where seismic activity is constant, experiences differ significantly: “There, people will say, ‘Well, I feel like it shakes all year round, not just in September.’”
Historical data helps dismantle this notion. The same 2021 study reviewed over 100 earthquakes of magnitude 7 or greater that occurred in Mexico between 1568 and 2021, finding no specific concentration in September. March and December each recorded 13 events, while September accounted for 12.
Another analysis conducted by UNAM researchers reached a similar conclusion after examining historical earthquakes. The occurrence of major seismic events can be observed at various times throughout the year and is not confined to September alone. The authors suggest that recent events, particularly those affecting Mexico City, have contributed to this collective association.
Future of Seismic Science
The advancement of technology has significantly transformed the capabilities of seismic science. Current networks detect smaller movements, allow for more accurate localisation of earthquakes, and aid in studying the behaviour of tectonic plates and faults. However, this knowledge still does not enable scientists to answer one of the most pressing questions following an earthquake: when will the next one occur?
“Given current technology, it is impossible to know the precise moment of generation because it involves numerous parameters,” Granados explains. To illustrate this, the seismologist uses the analogy of two pieces of sandpaper pressed against one another. While the direction of movement and the force applied may be known, determining the exact instant one will slide is complex. In the case of the Earth, the challenge is even greater, as the plates span hundreds of kilometres and conditions vary across their surfaces.
Granados elaborates that the most beneficial advancements help to better understand risk and mitigate its consequences: “Earthquakes cannot be predicted. What we can do is work to reduce the damage they may cause,” he asserts. This involves enhancing monitoring, construction regulations, alert systems, and public preparedness.
One thing science is certain of is that earthquakes will continue to occur, even if predicting their timing remains elusive. The key difference lies in how much we can learn and prepare before the next one arrives.