Although it can perhaps be an alluring notion, there’s very little convincing evidence that seismic waves – generated by earthquakes, or even nuclear weapons – can trigger volcanism. Could an asteroid impact, though? There are plenty of competing ideas about how valid such a concept is, but a new study in Science Advances puts it front and center at the most famous apocalypse in history: the demise of the dinosaurs.
The curtain call for the time of the Tyrannosaurus was a complex one. The non-avian dinosaurs had, in general, entered a 40-million-year-long period of decline, and at some point, a colossal volcanic event over in India began, and the profusion of what became known as the Deccan Traps wouldn’t stop for tens of thousands of years.
Then, of course, the coup de grâce: a 10 to 15-kilometers-wide (6 to 9.3-mile-wide) asteroid hit the Yucatan Peninsula, excavating a crater 180 kilometers (110 miles) across and sending debris 25 kilometers (15.5 miles) into the sky. It triggered a rapid, frigid climate change that brought the Cretaceous crashing down.
This new paper, by a pair of researchers from the Universities of Oregon and Minnesota, suggests that the impact was so energetic that its seismic waves boosted volcanism across the planet, specifically at mid-ocean ridges (MORs) within the world’s oceans. The team also infer that the aforementioned, ongoing, prolific eruption at the Deccan Traps was likely enhanced by the impact event.
If true, this paroxysm, and its associated uptick in climate and hydrosphere changing volcanic gases, would have contributed to the end-of-days environmental crises that were already happening at the time.
The team looked at publically available datasets focusing on the changes in gravity in Earth’s oceanic crust across a million years, both before, during and after the impact occurred. Small changes in local gravitational fields are good indicators of mass changes, and mass changes at MORs – where tectonic plates are separating – suggest changes in magmatic production.
The pair found that there was a transient change in MOR productivity around the time of the impact. Anomalies at MORs, found all over the world, from India to the Pacific Ocean, suggest that the volume of melt increased.
In fact, the team estimated that the amount of additional magma produced at MORs was at least comparable to that of the Deccan Traps, which was already known to have produced so much magma that it would have completely covered Spain.
“We put the volume of excess volcanic product at 100,000 to 1 million cubic kilometers of material,” co-author Dr Joseph Byrnes, a postdoctoral researcher at the University of Minnesota, told IFLScience. “This is a global episode of volcanism.”
Incidentally, the environmental impact of this pulse of global volcanism can’t yet be properly established. As this paper only used gravity data, Byrnes pointed out that “environmental changes in the ocean are a perfectly plausible consequence, but at this time the connection has not been quantitatively established.”