"You are looking at what we believe are all the volcanic eruptions that have occurred on our planet in the last 50-plus years, and all the earthquakes," Cottrell says. "And starting in 1978 with the launch of UV active satellites, you are seeing all the sulfur dioxide emissions from the volcanoes."
The data for the animation comes from Cottrell's program and the U.S. Geological Survey, as well as remote sensing satellites operated by NASA. According to Cottrell, the "E3 App" (three "E"s for eruptions, earthquakes and emissions) is the first visualization to consolidate all three data sets.
"That’s where the scientific power of a database like this comes in," she said. "Because you can start to look at the correlations."
For example, researchers who attempt to develop methods for forecasting quakes and volcanic eruptions might look at the app and find patterns that are difficult to recognize when looking at plain old numbers on a page. Forms of tectonic activity are almost always linked — earthquakes can trigger eruptions; movement of magma to the surface will send tremors through the Earth; some erupting volcanoes spew out huge plumes of sulfur and carbon, while others quietly belch gases all the time. The visualization aims to highlight links between the different phenomena that could prompt research on earthquake intervals, eruption size, tsunami probabilities and other characteristics of these events.
Findings from the Deep Carbon Observatory, a global research program aimed at understanding the way carbon cycles through the Earth, suggest that measuring the ratio of gas to carbon around volcanoes could help predict when they will erupt.
"Potentially, we can now see an eruption coming just by looking at gas emissions," geochemist J. Maarten de Moor, the lead author of a new study in the Journal of Geophysical Research, said in a statement.
Not shown on the app are years of data on quakes and eruptions before 1960, which the Global Volcanism Program has been collecting for almost 50 years. Using scientific observations, witness testimony, historical accounts and information from the geologic record, they are trying build a database of the planet's volcanic and earthquake activity since the beginning of the Holocene Epoch some 10,000 years ago.
It's a no simple task. Volcanic eruptions spew lava everywhere, creating a telltale rock signature that makes it easy for researchers to figure out when and where the outburst happened, even millennia after the fact. But earthquakes may shudder through the ground without leaving a lasting mark, and gas emissions can be as ephemeral as a cloud.
Identifying the links between the three E's could help Cottrell and her colleagues reconstruct what may have been happening in the ground and the atmosphere as prehistoric volcanoes erupted.
But beyond all the scientific applications, "It's just so cool," Cottrell gushed.
From the ground, it's easy to think of earthquakes and eruptions as dangerous, destructive and inimical to life. And it's true that these phenomena can be disastrous for the people who live through them. But tectonic activity is also part of what makes our planet habitable, according to Cottrell. It's a sign of the internal dynamo that produces Earth's protective magnetic field. It created the continents on which we now live. It may have supplied the fuel that gave rise to the very first organisms.
When earthlings go out in search of other habitable planets, we will measure the abundance of various elements to determine if they could house life. Oxygen is a sign of photosynthesis. Carbon could keep a planet warm. And something like sulfur could indicate volcanic activity and an internal dynamo that's still spinning.
If an alien spacecraft ever turned its spectrometers toward Earth, Cottrell said, its engineers may measure the emissions from volcanoes and think, "That’s the atmosphere of a planet that is still alive."