Few places in the world are as aptly named as Lost Lake, a mysterious body of water located in the mountains of Oregon that completely vanishes once per year, disappearing through a hole in its north side, according to various recently-published media reports.
As Jude McHugh, spokesperson for the Willamette National Forest, told the Bend Bulletin back in April, the hole has been there for as long as anyone can remember and was caused by an open lava tube, a type of geographic feature commonly found throughout the region.
Lava tubes form when flowing magma hardens near the surface while continuing to flow downhill closer to the still-hot interior, the newspaper explained. If the lava in the interior flows outward before it hardens, it leaves behind a tunnel-like structure that can either be opened to the surface following an eruption, or over time as a result of erosion.
McHugh noted that it is unclear if the water flowing into the lava tube’s hole travels to an outlet located somewhere else, but that odds are that it just seeps into the porous subsurface, adding to the large aquifer which feeds springs on both side of the Cascade mountains.
According to the Washington Post, Lost Lake empties out in the winter after the snowpack of the mountain range freezes, drying up the source of inflow that the body of water relies upon to keep filled. Once the snow melts in the summer, it fills up again. Officials said that a similar lava tube drain exists at nearby Fish Lake, which also experiences a similar seasonal cycle.
Asking the experts: How unique is Lost Lake?
So just how common is this phenomenon? RedOrbit asked Kathryn Thorbjarnarson, associate professor in the San Diego State University Department of Geological Sciences, and she explained that lava tubes “are typically found in geologic settings of basalt lava flows,” which “tend to be associated with oceanic hot spots” such as those found in Hawaii and Iceland.
“Lava tubes are common in those regions with ones above the water table able to be hiked through,” such as Thurston lava tube in Hawaii Volcanoes National Park, Thorbjarnarson said via email. The Columbia and Snake River plateaus also have plentiful basalt lava from past eruptions, she said, and Lava Beds National Monument in northern California is home to lava tubes historically used “by Native Americans in wars to hide and to launch sneak attacks.”
How unusual is it for something like this to happen, where a lake winds up being completed drained? In most cases, the professor explained, seepage or evaporation loss resulting from these lava tubes is “a slow process,” with the water level dropping when outflows exceed inflows.
“What is unique in this situation is the relatively fast drop as inflows are drastically stopped (snowpack solid and no melt water) and the seepage through the large lava tube network results in a fast drop in water level and draining of the lake,” Thorbjarnarson said. “When the snowpack starts to melt again, the inflow exceeds the drainage rate and the lake fills up again.”