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Study Reveals Risk of Harmful Earthquakes in Northeast Brazil in the Next Decades

A study titled "Probabilistic estimation of the source component of seismic hazard in North-Eastern Brazil" indicates that damaging earthquakes are likely to occur in the Northeast region in the next five decades.

 

The research was conducted by José Augusto Silva da Fonsêca and Aderson Farias do Nascimento, from the Federal University of Rio Grande do Norte (UFRN), and Stanislaw Lasocki, from the Institute of Geophysics of the Polish Academy of Sciences, and published in the scientific journal Cell.


The results were achieved by analyzing data from the Brazilian Seismographic Network (RSBR) catalog from 1990 to 2020, considering four regions that include different municipalities. According to the study, northeastern states are at a significant risk of facing earthquakes with magnitudes between 4.7 and 5.1 on the Richter Scale.



The researchers' calculations also indicate a 50% probability of this catastrophe occurring and affecting structures such as houses and buildings. Furthermore, there is a 10% probability of earthquakes with magnitudes between 5.5 and 6.2, which could pose risks to large civil works, such as dams, wind farms, mining, hydroelectric, and nuclear plants.


Despite the perception that Brazil is earthquake-free, tremors occur almost weekly. Last year alone, the UFRN Seismological Laboratory recorded 182 earthquakes in Bahia. Although most of the Brazilian territory is located in South America's Stable Continental Region (SCR), one of the least seismically active in the world, relatively strong tremors can still occur.



The collision between tectonic plates causes earthquakes. The planet's lithosphere is fragmented into several plates that float on the Earth's mantle. When these plates collide, an earthquake occurs. Although Brazil is on a large plate far from the edges, the South American plate has cracks and faults in certain regions. As a result of the intense movement of the plates, these areas can accumulate energy and release it in the form of tremors.



These tremors resulting from cracks are generally smaller, ranging between 2 and 4 on the Richter scale, and, in most cases, are not felt by the population. However, larger tremors may occur. At the beginning of the year, the North region recorded a 6.6 magnitude earthquake, the largest in the country's history, but due to the depth of the tremor, no damage was recorded.


In June 2022, a 6.5-degree earthquake was recorded in the municipality of Tarauacá in Acre, the second largest in Brazil, also with no victims or material damage. In the last 45 years, almost one hundred earthquakes have occurred within a radius of 250 kilometers from Tarauacá without serious consequences. This occurs due to the proximity of this region to the Andes Mountains, one of the most seismically active areas on the planet.

 


That said, magnitude five tremors are considered moderate events and occur with particular frequency in the Northeast, one of the regions with the most significant seismic activity in the Stable Continental Region of South America. Aderson Farias do Nascimento points out that, although it is impossible to predict earthquakes precisely, statistics can help prevent these events by investing in lasting structures, such as bridges and dams.

 

Nascimento also highlights that adequate preparation can mitigate the consequences. An example is the current situation in Rio Grande do Sul, which still suffers repercussions from floods and flooding in the region.

 

Brazil does not have a structure or plans for natural disasters, as these are not common events in the national territory. But how much have these been costing the population of Rio Grande do Sul? The situation in Rio Grande do Sul should be taken as an example so that the population and responsible municipal, state, and federal bodies act to develop prevention and awareness of such events in the country.


This preparation involves constant monitoring, well-structured civil defense, advice from public authorities, contingency plans, building codes, and education. "It's a question of cultural change," says Nascimento, emphasizing the importance of a society prepared for these threats.



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