Outburst floods are common in western Canada.
Lakes dammed by glaciers or moraines suddenly drain and tonnes of water, mud and debris are released. An outburst flood typically occurs when the water level becomes high enough to actually float the ice or when a small channel forms under the ice and causes rapid melting, thus expanding the channel. Another common mechanism is overtopping of the ice dam and the rapid thermal and mechanical erosion of a channel, leading to catastrophic drainage. In all cases, the new channel increases rapidly in size and releases the lake water quickly. The release of water is often sudden and catastrophic.