How satellites have revolutionized the study of volcanoes
The development of satellite technology over the past decade has allowed the world to witness the devastating Hunga Tonga-Hunga Ha’apai eruption and its aftermath in unprecedented real-time and detail. The findings may shed light on the anatomy of rare explosive volcanic eruptions and their effect on the planet. But satellites are also helping volcanologists track Earth’s more common (albeit less eye-catching) outbreaks.
The last time a volcano erupted as violently as in Hunga Tonga-Hunga Ha’apai was 30 years ago. Then, the monitoring satellite The earth very few and far. Surface observers are mostly run by the military. The European Space Agency (ESA), now an Earth-observing superpower, is just about to launch its first Earth-observing mission, the Remote Sensing Satellite-1 (ERS-1). Since then, the cubes that have become the basis of commercial Earth-observing constellations, such as that of the US-based company Planet, have yet to be invented.
Still Mount Pinatubo erupts 1991 was the most explosive volcanic event detected by satellite at the time, captured by a Japanese weather satellite 22,000 miles (36,000 km) above Earth and a NASA spacecraft. The US National Oceanic and Atmospheric Administration orbits the planet in polar orbit.
Related: Ash from Tonga volcano erupts to record high, but climate is hard to cool
In real time
But the detectors and cameras on satellites in the 1990s weren’t as capable as those orbiting the Earth today. And so the amount of data doesn’t have much detail about what the Hunga Tonga-Hunga Ha’apai eruption produced.
Simon Proud, a researcher in satellite data and meteorology at the University of Oxford, told Space.com: “In a sense, we’re really lucky to have all of these satellites on the planet. trajectory. “This is something we wouldn’t have even five years ago.”
Proud is one of hundreds of researchers around the world intrigued by the data pouring in from the following orbital sensor networks: Hunga Tonga-Hunga Ha’apai . eruption ripples across the southern Pacific Ocean on Saturday (January 15). The first was a nuclear-like explosion, which has since been described as 500 times more powerful than the Hiroshima bomb. Then there was the shock wave that circled the globe, confusing weather models around the world, and the ash cloud rose to unprecedented heights in the atmosphere.
That volcanic cloud was of particular interest to Proud. Since then, he noticed that it had reached a record altitude of more than 30 miles (50 km).
“Our latest data show that the main volcanic ‘umbrella’ reaches 35 km [22 miles] altitude, but some points may have reached 55 km [34 miles] height! “ say on Twitter, adding that “the shocking altitude … shows how intense this eruption was.”
However, he cautions that this record is partly due to the availability of measurement technology.
“We thought Pinatubo could go that high, too, but we missed it with the technology we had,” he said. “What’s really interesting from a science perspective about this event, is how high it rose and how over the coming days and weeks it will interact with the atmosphere there.”
Scientists have known that the Hunga Tonga-Hunga Ha’apai volcanic cloud contains relatively low amounts of sulfur dioxide, such as the eruption of Mount Pinatubo. Sulfur dioxide is of great interest because it can reflect sunlight as it is dispersed in the atmosphere, thereby changing how much heat the planet traps. Due to its sulfur dioxide content, Mount Pinatubo’s eruption cooled the planet by 1 degree Fahrenheit (0.6 degrees Celsius) in a way that could be measured in two years. However, current estimates suggest that despite the incidence of cataclysmic events, the Hunga Tonga-Hunga Ha’apai volcanic cloud contains only 2% of Mount Pinatubo’s sulfur dioxide.
Unopened bottle of champagne
However, the difference is not due to the size or force of the explosion, volcanologist Jeffrey Karson of Syracuse University in New York, told Space.com.
“That has to do with the origin of the molten rock at the depths,” Karson said. “Some volcanic materials are high in sulfur, some are very low in sulfur. That depends on the source.”
The force of the Hunga Tonga-Hunga Ha’apai explosion, the largest explosion the planet has seen since Mount Pinatubo erupted in 1991, was the result of a combination of factors, according to Karson.
“There is nothing geologically unusual about this volcano,” Karson said. “It’s one of thousands of volcanoes around the Pacific Rim, the so-called ‘Ring of Fire,’ where the Pacific Ocean is being crammed beneath the surrounding lithospheric plates. That’s the driving process. most of the volcanoes on our planet.”
Water mixed with magma causes chemical reactions not found in volcanic eruptions on dry land. Water mixes with molten rock, creating bubbles. High temperatures in the volcano’s vents pressurize this mixture like a bottle of champagne. At some point, the pressure was high enough to shift the “cork” on that volcanic champagne bottle. How long the volcanic “cork” stays in place and how violently it flies depends on the water column above, Karson said.
“If there’s a lot of pressure on the system, or in other words, the water is relatively deep, then the lids are kept on that system and the gas comes out pretty slowly,” says Karson. “If it’s close to the surface, there’s no water pressure to keep the cap on the system and those gases escape catastrophically.”
Karson says the gas can expand a thousand times in volume when it changes from a liquid state; an instantaneous process, blowing up rocks with explosive force.
Where will the next one explode?
The satellite plays an integral role in monitoring the Hunga Tonga-Hunga Ha’apai eruption, Karson admits. Volcanologists place sensors on volcanoes that they believe might work. But very little is known about Earth’s internal processes, and the best estimates are rudimentary.
“We don’t know when the next eruption will take place on a particular volcano, so we place the instruments on the mountains that we consider the most active,” Karson said. “But this particular volcano is not very instrumental.”
Despite the technology boom of the last decade, satellites still don’t provide as detailed images as sensors on the ground. However, much can be learned from their data and images about the scale of the impact, the spread of the volcanic cloud, and the changes to the topography around the volcano.
“There’s a lot that can be done,” says Karson. “For example, you might wonder how much the ground has changed and that can also be determined from satellites these days. But for example, gases are dispersed in the atmosphere. and can ultimately be diluted and difficult to measure from great heights.
Slow burning destruction
Karson’s main research interest is in slow-burning, more modest volcanoes that produce lava over weeks and months, often causing more severe but predictable damage that people can’t imagine. can prepare for. Even those volcanoes benefit from satellite monitoring. For example, damage caused by Cumbre Vieja . Volcano on the Canarian island of La Palma in the Atlantic Ocean last year was evaluated in near-daily detail by satellites of the European constellation Copernicus. Analysts can count each building that has disappeared in the lava river and calculate the exact area of land buried by molten rock.
“Today, photography is quite common even in remote areas [volcanic eruptions] with satellites,” Karson said. Nowadays, there are more and more satellites. They have different systems on them and so we’re much better positioned to do different types of observations. “
Cloud tracking
Karson adds that the size of a volcanic eruption may not be directly proportional to its intensity.
For example, the 2010 slow-burning eruption of Eyjafjallajökull Volcanoes in Iceland produce large amounts of ash that is extremely dangerous to aircraft. Nearly 100,000 flights were halted on busy transatlantic routes as a result of the eruption.
On the other hand, the Hunga Tonga-Hunga Ha’apai threw its debris over a fairly remote area of the Pacific Ocean without many passing flights. However, scientists still carefully watched the cloud’s spread, the cloud overtook Australia and began to spread over the Indian Ocean.
“The ash cloud will eventually spread very thinly around the globe,” Proud said. “For the next few weeks, it will likely remain in the Southern Hemisphere, following winds across the southern Indian Ocean and toward southern parts of Africa.”
Currently, most of the cloud is above the plane’s flight altitude, he added. Even if the explosion has ended, the satellites will still keep an eye on Hunga Tonga as well as the volcanic cloud for weeks to come. Proud said some unexpected insights could emerge from the study. For example, because of its altitude, volcanic ash can interact with the ozone layer, which has never been studied before.
Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and more Facebook.
https://www.space.com/how-satellites-revolutionized-study-of-volcanoes How satellites have revolutionized the study of volcanoes
