Scientists were shocked to discover a giant underwater crater on the floor of a Swiss lake during a routine measuring run.
Researchers were taking measurements on Lake Neuchatel using a research vessel when they noticed a strange shape pop up on the control panel screen, ETH Zurich reported. The shape was something that no scientist had ever seen before. An analysis revealed that what the scientists had found was an enormous crater measuring at over 30 feet deep and almost 530 feet in diameter.
"I'll remember this day for a long time -- I never expected anything like this," said Anna Reusch, a doctoral student at ETH's Geological Institute who first spotted the stunning crater. "It just goes to show that even in the 21st century, there are still thrilling and exciting discoveries to be made in Switzerland!"
The project that led to the crater's discovery was originally aimed to use high-resolution measurements of the floor of Lake Neuchâtel to pinpoint tectonically active zones that could trigger major earthquakes; but the craters proved to be more interesting.
The researchers have now located four craters on the lake bed, and most extend into tectonic fault zones. Researchers nicknamed the largest of them "Crazy Crater," because of its giant size and peculiar perfectly-round shape. A closer look revealed the Crazy Crater was filled with mud that covers a vent holding a thick suspension of water and sediment.
An isotope analysis and temperature measurement of the suspension, sediments, and water, showed water was flowing from these craters, as opposed to gas. While the deep water and sediment surrounding the crater was chilly, the suspension was closer in the warmer temperature measured at the surface of the bordering karst area. The suspension within the vent also proved to have a smaller concentration of the heavy oxygen-18 isotope than the surrounding water.
"The difference in these oxygen signals indicates that we're talking about two distinct bodies of water here," Reusch said.
The researchers believe these findings mean the craters are intertwined with the karst systems of the Jura Mountains. Water most likely seeps underground and moves below the lake bed and is drawn to areas with the lowest resistance.
"In other words, these craters are in fact springs," Reusch said.
Sediment cores sampled from around the craters revealed the suspension occasionally spills over the lip of the features in a similar fashion to a volcanic eruption. This has occurred at least four times over the past 12,000 years, but it has been 16,000 since the Crazy Crater expelled sediment. Exactly what causes these events is yet to be determined.
"Researching the dynamics of the craters requires long-term monitoring to keep an eye on the water level of the suspension in the crater," Reusch said.
The findings were reported in a recent edition of the journal Geophysical Research Letters.
