Lake breakout

Lake breakout is when a lake suddenly collapses, usually a lake that forms high up in the mountains. These high places often have lakes in volcanic craters, called crater lakes, or in valleys blocked by earthquakes, glaciers, or volcanic deposits.

Such lakes can break out, especially a few weeks or months after a volcanic eruption. When this happens, a lot of water can rush out very fast. This can sometimes cause floods and damage nearby.

Learning about lake breakouts helps scientists and communities get ready for and respond to these natural events.

Process

High-altitude lakes can sometimes become unstable, especially after earthquakes or because of erosion. If the walls of these lakes break, water rushes out. This creates a wider and deeper channel, causing more water to flow out. The lake’s rim can collapse suddenly. This leads to a huge flood of water that carries a lot of sediment. These floods and mudflows, called lahars, can be dangerous to towns or villages nearby.

Historical events

One of the largest lake breakouts happened about 15,000 years ago when an ancient lake called Lake Bonneville broke through its shores. This lake, filled with water from the last ice age, covered parts of Utah, Idaho, and Nevada. When it burst, it released a huge amount of water that changed the land, shaping the Snake River and its area. Another famous breakout was from Glacial Lake Missoula, which also caused major changes in eastern Washington. Some scientists think that similar breakouts on Mars might have carved its canyons.

Mitigation

Many lake breakouts cannot be stopped, but some have been prevented or delayed with help. For example, after the 1980 eruption of Mount St. Helens, a lake formed that could have caused a dangerous flood. The United States Army Corps of Engineers dug a channel to let the water flow safely. This helped keep the lake from overflowing its debris dam.