A team of researchers from the Catholic University has identified a persistent seismic cluster beneath the southern sector of Santiago, consisting of 1,389 low-magnitude earthquakes. The finding, reported by BioBioChile, reveals an area of concentrated seismic activity at depths ranging from 20 to 30 kilometers.
These events, which scientists refer to as 'families' due to their similarity, are characterized by the fact that they do not originate from a single, larger mainshock. Using advanced detection techniques, the scientists were able to locate these movements which, due to their low intensity, typically go unnoticed by the public.
Geophysicist Cristian Farías, an associate professor at the Universidad Católica de Temuco, explained that a seismic cluster acts as a zone where earthquakes concentrate within a specific area rather than dispersing. According to the specialist, this phenomenon can be observed in both volcanoes and shallow faults in various parts of the country.
An active fault zone beneath the capital
Farías noted that the discovery is significant because the application of new techniques allowed for the detection of earthquakes that were previously difficult to capture. "It means you have a fault zone where earthquakes are constantly being generated—nothing very large, but they are certainly there," the geophysicist stated in an interview with BioBioChile.
The expert clarified that this phenomenon should not be confused with a seismic swarm, which occurs over a very short period, nor with earthquake aftershocks, which gradually decrease in frequency. The cluster detected under Santiago remains sporadic but constant over the years.
Regarding public safety, Farías dismissed the idea that the finding foreshadows an imminent catastrophic event. "It does not mean we are seeing the precursor to a much larger earthquake in Santiago. That is not what the data shows so far," he assured.
Nevertheless, the geophysist indicated that the presence of these earthquakes suggests the existence of a seismic source that was not well understood. Current hypotheses consider the possible presence of active faults or the movement of fluids at great depths. Studying this data will allow for improved seismic risk models for the country's central region.
