Lake breakout

Lake breakout is the sudden collapse of a lake, usually one that forms at high altitudes. These high-altitude lakes often appear in volcanic craters, known as crater lakes, or in valleys that get blocked by earthquakes, glaciers, or volcanic deposits. Such lakes are vulnerable to breaking out, especially a few weeks or months after a volcanic eruption, when volcanic debris can block a river and create a dam that eventually fails. When a lake breaks out, it can release a large amount of water very quickly, sometimes causing floods and damage in the surrounding areas. Understanding lake breakouts helps scientists and communities prepare for and respond to these natural events.

Process

The walls of high-altitude lakes can sometimes become unstable, especially after earthquakes or due to erosion. When the walls break, water rushes out, creating a wider and deeper channel that causes even more water to flow. This can lead to the lake’s rim collapsing suddenly. The result is a huge flood of water that carries along a lot of sediment, making the flood even larger and more powerful. These floods and mudflows, known as lahars, can be very dangerous to any towns or villages in their path.

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

Although many lake breakouts cannot be stopped, some have been prevented or delayed by human 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 an outlet channel to let the water flow safely and avoid a big problem. This helped keep the lake from overflowing its debris dam.