The Yellowstone National Park is again squashing rumors of a supervolcano eruption to come, and while the government says it is not hiding evidence about the Yellowstone Caldera, some people aren’t buying it.
The Caldera is a massive volcano that has the potential to produce huge eruptions, but no, there are no indications right now that any sort of eruption will happen any time soon. Scientists say there won’t be any eruption in our lifetime. It won’t be the first volcano that hasn’t exploded in the past 70,000 years.
However, a new study by Jamie Farrell and others in the Geophysical Research Letters examined the geometry and properties of the Yellowstone magma reservoir using seismic data from earthquakes registered on the Yellowstone Seismic Network between 1984-2011.
This massive collection of seismic data was applied to models in an effort to determine what the likely composition of the material beneath the caldera is. Farrell and his team did this by examining anomalies in the speed of seismic waves, where low velocity zones correlate with areas that could harbor magma, hydrothermal fluids, gas or other fluids. They can then render models of the areas.
Based on the collected data, Farrell and others have modeled a large, shallow zones of lower seismic velocity that they interpret as the magmatic system beneath the Yellowstone Caldera. This isn’t surprising as it has been imaged before. However, these new data also reveal a zone extending from the northeast boundary of the caldera that they interpret as a zone of shallow magma or hydrothermal fluids (or both). So, the magma body at Yellowstone might extend outside the known boundary of the caldera.
The Yellowstone hotspot is stationary and North America is moving across it, burning a path known as a hotspot track. As time goes by, the focus of magmatism at Yellowstone should be moving to the northwest.
Overall, Farrell and others (2014) think that the total volume of the Yellowstone magmatic system is ~200-600 cubic kilometers of melt (the range reflects the uncertainties in their models), which is much more melt than previous estimates. This volume is smaller that two of the three largest Yellowstone eruptions, but within range of the 1.3 million-year-old Mesa Falls Tuff that erupted ~280 cubic kilometers of rhyolite ash and volcanic debris.
“The new findings do not imply increased geologic hazards at Yellowstone, and certainly do not increase the chances of a ‘supereruption’ in the near future,” Farrell and his team wrote.