If you get too close to the hydrothermal vents scattered throughout Yellowstone National Park, you'll notice a strong smell reminiscent of rotten eggs. These calderas are a (literal) breeding ground for harmful gases such as hydrogen sulfide and carbon dioxide, but one gas is surprisingly in short supply.
The lack of sulfur dioxide in Yellowstone seems a mystery. Other volcanoes, such as Mount Etna in Italy and Santorini in Greece, emit tons of the substance each year.
According to Jennifer Lyn Lewicki, a research geologist at the US Geological Survey's (USGS) California Volcano Observatory, the sulfur dioxide in Yellowstone is not actually gone. Instead, it undergoes underground transformation, turning into hydrogen sulfide and dissolved sulfate ions before reaching the surface.
In the Yellowstone Volcano Observatory's Caldera Chronicles, Lewicki explains that this is good news for residents in nearby states because the presence of sulfur dioxide can signal volcanic unrest.
Important volcanic gases
Magma is more than just molten rock. It contains several dissolved gases, including water vapor, carbon dioxide and sulfur dioxide.
As magma flows toward the surface, the decrease in pressure causes gases to escape from the liquid magma and continue to rise to the surface, eventually escaping into the atmosphere, a process known as degassing.
It is important to note that different gases have different levels of solubility. Sulfur dioxide has a relatively high level of solubility and does not often escape from the magma until it reaches shallow depths.
Read more: One of the oldest organisms on Earth lives in the scorching hydrothermal vents of Yellowstone.
Where did the sulfur dioxide go?
Essentially, the absence of sulfur dioxide in Yellowstone is boiling This can be explained by two factors: the depth of Yellowstone's magma chambers and the interaction of hydrothermal systems.
Unlike Hawaii's Kilauea, where magma is stored in shallow reservoirs just a mile or two away (1 to 5 kilometers),) below the surface Yellowstone magmatic system lies deep underground.
There are two chambers, with the shallower of the two located 3 to 10 miles (5 to 17 kilometers) below the surface. The deeper (and much larger) of the two lies 12 to 30 miles (20 to 50 kilometers) underground and is 4.5 times larger than the first. This depth means that very little of Yellowstone's sulfur dioxide escapes from the magma at all.
The fact that Yellowstone also contains a large hydrothermal system, including thousands of hydrothermal features, from hot springs to geysers, means that any sulfur dioxide that does escape interacts with the water before it reaches the surface.
Through a process called “scrubbing,” water converts sulfur dioxide into several other substances, including hydrogen sulfide, dissolved sulfate ions, and elemental sulfur.
Predicting Volcanic Unrest
While sulfur dioxide is often used as a monitoring tool to help scientists track volcanic activity levels, its absence in Yellowstone may well be a good sign.
A sudden change in sulfur dioxide levels could indicate changes beneath the surface, Levitsky said. Yellowstone and may indicate that magma has risen closer to the surface, causing water to evaporate. This could signal volcanic unrest.
But even if an eruption occurs, the USGS predicts it will likely be a hydrothermal explosion, a relatively small event that occurs about once every few years. As for the so-called “super eruption”, volcanologists doubt that there will ever be another catastrophic eruption like the one that occurred 2.08 million years, 1.3 million years and 0.631 million years ago. At least for now, the magma present in Yellowstone appears to be too widespread to threaten an eruption. Nature.
“Most volcanic systems that experience supereruptions do not occur multiple times. When supereruptions occur more than once in a volcanic system, they are not evenly distributed over time,” according to US Geological Survey. “The rhyolite magma chamber beneath Yellowstone is only 5-15% molten. […] therefore, it is unclear whether there is enough magma beneath the caldera to fuel an eruption.”
Read more: Yellowstone bison meets tragic end in hot spring, demonstrating dangers of hydrothermal events
Article sources
Our authors in discovermagazine.com use peer-reviewed research and high-quality sources for our articles, and our editors review scientific accuracy and editorial standards. Review the sources used below for this article:
