What happened

Brazil's National Interconnected System experienced an unplanned separation between its North and Southeast regional grids at a 500 kV circuit near Imperatriz, Maranhão, at around 8:30am Brasília time on 15 August 2023, interrupting an estimated 19 gigawatts of electric load — about 27% of the country's total load at that moment. The blackout affected the Federal District and every Brazilian state except Roraima, which is not connected to the national grid; the North region saw an 83.8% power drop and the Northeast a 44.4% drop, with the South and Central-West regions also affected. Five São Paulo subway lines were disrupted with service not fully restored until 9:25am, Salvador's metro stopped with passengers evacuating along the tracks, water supply was suspended in parts of Amapá, schools in Manaus dismissed students, and internet and telecommunications services were interrupted in some areas. Grid operator ONS and utilities restored the South region by 9:05am, the Central-West by 9:33am, the Southeast by 11:00am, and achieved complete nationwide restoration by 2:49pm — roughly six hours after the initial failure. Minister of Mines and Energy Alexandre Silveira established a crisis response chamber and asked the Federal Police and Brazil's intelligence agency (ABIN) to investigate whether human action contributed to the blackout; the exact technical cause remained under investigation in the sources reviewed, and no sabotage was confirmed. This record therefore documents the event as an operational grid failure, pending resolution of the human-action question raised by the government's own request.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.