Brazil is classified as a medium hazard level, which means that there is only a 10 percent chance that Brazil will experience a potentially damaging earthquake in the next 50 years (http://thinkhazard.org/en/report/37-brazil/EQ). Earthquake risks are relatively low in Brazil compared to many other South American countries, but low and medium intensity hazards occur at a certain frequency in Brazil. On November 5, 2015, the Fundao tailings dam of Brazil collapsed due to  a series of earthquakes with the magnitude of 2.01 to 2.55, which caused the worst environmental disaster in Brazilian history. In Brazil on average, magnitude 3 earthquakes occur twice a month, magnitude 4 earthquakes occur twice a year, and magnitude 5 earthquakes occur once every 50 years (https://phys.org/news/2017-08-seismic-hazards-brazil.html). Since Brazil does not really experience "big" earthquakes, they do not have to worry too much. In 2015, the dam that fell was just fragile and was not built for earthquakes. According to the international committee that analyzed the dam and the dam geotechnically, low magnitude earthquakes cannot endanger well built structures. Now, dams that are built in Brazil must perform seismic hazard studies before their designs are approved.