BTN News: A powerful earthquake of magnitude 5.3 on the Richter scale struck off the southern coast of Lisbon, Portugal, on Monday, reverberating across nine Spanish autonomous communities. The earthquake, which was recorded by the National Geographic Institute (IGN) of Spain, sent tremors through Galicia, Asturias, the Basque Country, Navarra, Castilla y León, Castilla-La Mancha, the Community of Madrid, Extremadura, and Andalusia.
Southern Portugal’s Earthquake Most Noticeable in Southern Spain, Especially in Huelva
The most significant effects of the earthquake were felt in the province of Huelva, situated closest to the Portuguese border. Within Huelva, the Isla Canela beach in Ayamonte and the town of Cortegana experienced the highest intensity, reaching a level IV on a scale of X. According to the IGN, at this intensity, many people inside buildings can feel the tremor, while few outside notice it. The vibration is enough to wake some people but generally does not cause alarm.
Why the Atlantic Region Near Lisbon is Prone to Earthquakes
Carlos González, a seismologist from IGN, explained that the earthquake occurred in an area that is “full of faults” and is “tectonically complex.” Earthquakes in this region are not uncommon due to the intricate network of tectonic plates. Although aftershocks are expected, González noted that because the earthquake occurred in the ocean, smaller aftershocks might be challenging to detect.
Comparison to Past Earthquakes: Lessons From Lorca and Lisbon
González drew a comparison with the 2011 Lorca earthquake in Murcia, which had a similar magnitude of 5.1 but resulted in nine fatalities and significant structural damage. The key difference, he explained, is that the Lorca earthquake occurred just two kilometers beneath the surface, near a densely populated area, while the recent Lisbon earthquake was much deeper, between 20 and 30 kilometers.
The damage caused by an earthquake of magnitude 5.3, according to González, is generally limited unless it strikes a region with poor infrastructure. He cited the devastating earthquakes in Haiti (2010) and Nepal (2015), both exceeding magnitude 7, where weak buildings contributed to high casualty numbers. In contrast, countries like Japan, with more robust infrastructure, tend to suffer less damage from similarly powerful earthquakes.
The 1755 Lisbon Earthquake: A Historical Perspective
Raúl Pérez López, a geologist with the Spanish Geological and Mining Institute (IGME-CSIC), provided historical context by referencing the Lisbon earthquake of 1755, which struck slightly south of Monday’s event. That historic earthquake and the subsequent tsunami claimed over 1,200 lives. Pérez cautioned against making direct comparisons between different earthquakes, as various factors influence their impact.
Pérez also explained that while a magnitude 6.5 earthquake releases energy equivalent to that of the Hiroshima atomic bomb, Monday’s 5.3 earthquake was much less powerful—about 32 times weaker. However, he emphasized that equating earthquake energy with bomb energy is not straightforward, as the effects differ significantly.
Spain’s Emergency Preparedness: Lessons from Past Events
Pérez acknowledged that Spain has robust emergency plans in place, but he also admitted that complete preparedness for such events is impossible due to the unpredictable nature of natural disasters. He cited the 2021 volcanic eruption on La Palma as an example of how, despite strong preparation, the reality of a disaster can still pose significant challenges.
In this light, Pérez noted that non-destructive earthquakes like the one near Lisbon are invaluable for refining models and improving future preparedness. The data collected from such events help scientists, emergency services, and the military fine-tune their response strategies. For instance, if a future earthquake were to reach magnitude 6.5, the lessons learned from milder quakes could guide emergency simulations and planning.
Conclusion: A Wake-Up Call and an Opportunity to Improve Earthquake Preparedness
Monday’s earthquake near Lisbon serves as a reminder of the seismic activity in the region and an opportunity for experts to enhance their understanding and preparedness. While the tremor was felt across a wide swath of Spain, it fortunately did not cause significant damage. The event underscores the importance of ongoing collaboration between scientists, emergency responders, and the military to ensure that Spain is as prepared as possible for future seismic events.
