On October 4, 2010, the retaining wall of a caustic waste reservoir at the Ajka alumina plant near Kolontar, Hungary, collapsed, releasing more than one million cubic meters (38 million cubic feet) of highly alkaline red sludge. The thick wave of waste material flooded several nearby villages, killing 10 people, injuring more than 120, and leaving many with chemical burns on their skin. The sludge eventually found its way into local rivers, killing many animals. One year later, damaged buildings have been razed, much of the land has been cleaned up, and MAL Hungarian Aluminum has been fined $647 million (472 million euros) for environmental damages. Today, monitoring shows lower toxicity than many had feared, but the levels are still dangerous. Gathered here are older and recent images from the disaster, including five before-and-after photo pairs (starting with photo number 15) that you can click to see the difference a year can make.