Garibaldi lake is located 37 kilometers north from Squamish, British Columbia. The water is dammed by a lava formation known as the Barrier. The Barrier is about 300 meters thick and 2 kilometers wide.

How much water does Garibaldi lake contain?

In order to calculate roughly how much water Garibaldi lake contains I took the surface area of the lake and multiplied it by the average depth.

Surface Area = 9.94km^2 =  9940000m^2

Average depth = 119m

Amount of water in lake = 9.94 x 10^6 x 119

Amount of water in lake = 11182860000000 L or 1.2 x 10^13 L

What would happen if the Barrier broke? 

Most of the water would escape however not all of the water would be drained. Since the bottom of the lake isn’t completely smooth and slanted downwards towards the Barrier, some water would still remain in the lake. The floor of the lake is uneven therefore creating areas where water could pool instead of flowing away.

According to a Quest University student named Greyson Herdman, who was hired by the District of Squamish to write a flood report and study the hazards Squamish would face in the event that the barrier breaks, “If the barrier were to explode or fall apart in an earthquake, the wave that would be produced by all that water flowing out of Garibaldi Lake down into Squamish would be 120 metres high.”

Dr. Quane believes that if the barrier breaks, Squamish would be completely wiped out. He states “The potential energy at 1,400 meters elevation, of 1 trillion liters of water, is 200 times the energy released by the bomb on Hiroshima.”

Sources

http://www.squamishchief.com/news/garibaldi-lake-a-ticking-time-bomb-1.1753732

https://en.wikipedia.org/wiki/Garibaldi_Lake