Numbers are great. We need them to quantify how our universe changes.
From counting coins in our wallet to calories in our dessert to birds in the sky and the stars in the cosmos — numbers express growth, decay, magnitude, and loss. They tally neutrinos, quarks, and black holes.
But beyond the sorts of values used in our everyday lives, numbers become unfathomable. Consider the months-long 2018 eruption of Kīlauea. From late April to early August, that volcano oozed 30 billion cubic feet of molten rock. That’s difficult to imagine, so another value was cited: that’s equivalent to 320,000 Olympic-size swimming pools. But who can picture that many swimming pools inside their head? Is it any more helpful?
The point, I suppose, was to say: that was a lot of lava.
And it was. But nothing beats seeing it with your own eyes: photographs of seething magmatic blood pouring from fresh wounds in the side of a giant volcano, or fiery fountains shooting high into the night sky. Numbers are great, but seeing is believing.
This month’s eruption of Hunga Tonga-Hunga Ha‘apai, a mostly submerged cauldron-shaped volcano in the South Pacific, was the horrific, perfect testament to this.
Gravity Waves Seen from the Eruption.
It was immediately clear to observers that, after a few weeks of moderate eruptive activity, the explosion on January 15 was nothing short of cataclysmic. The latest estimate of the explosion’s energy, courtesy of a nuclear-test monitor, compares it to detonating 50 million tons of TNT — twice the explosive fury of the May 1980 sideways blast at Mount St. Helens, and roughly equivalent to the Tsar Bomba, the most powerful nuclear device ever detonated.
The tsunami that inundated Tongatapu, the Kingdom of Tonga’s main island, destroyed homes, livelihoods, and lives. And the high-pressure wave of air managed to push on parts of not just the Pacific Ocean, but the Atlantic Ocean too, creating multiple tsunamis entirely separate from the one generated by the volcano’s underwater rupture. Standing above this widespread destruction was a plume of glassy ash rising 34 miles skyward which, depending on the metric you use, is halfway or two-thirds of the way to space. And from that plume, hundreds of lightning discharges were flashing through every single second, accompanied by the deafening, relentless drumbeat of thunder.
Anyone can read this short summary of the events of January 15 and think: holy shit, that eruption was gargantuan. But for most of us, those fortunate enough to be geographically removed from the pandemonium, I’m not sure words alone, evocative though the facts alone may be, really does that day justice.
Photographs are the most effective means — and in this case, our only way to not just know what happens when the sky is falling, but to actually feel what it is like, so to speak. But unlike most volcanic outbursts, this isolated paroxysm could only be fully chronicled by our orbiting eyes in the skies. And the satellite images that quickly shot around social media in the minutes and hours after that titanic explosion made almost everyone feel precisely the same way. They felt small.
The blast was so powerful that it generated a shockwave that quickly traversed the planet three times, something you could see via two satellites with striking clarity. You could even see both sides of the circular wave converge in Algeria, all the way on the other side of the planet. Gravity waves (not to be confused with gravitational waves,) are eerie undulations in the air and were also seen via satellite moments after the explosion. The extreme volcanic activity in the hours preceding the big blast turned what was originally an island-building eruption into an island annihilating one, a process of creation and destruction recorded by cameras hundreds of miles away. Three weather satellites, usually content with tracking billowing storm clouds and spiraling hurricanes, witnessed that dark ashen maelstrom rocket its way toward the stars at close to the speed of sound.
Satellites weren’t alone in their unique perspective on the eruption. Kayla Barron, a NASA astronaut aboard the International Space Station, was able to see the volcano’s vast veil of ash blanket the Southern Hemisphere. At the same time, satellites saw that veil fall to Earth, smothering crops, waterways, roads, and runways, those that hadn’t been washed away by the tsunami.
Altogether, this is staggering stuff, the sort of thing that moves volcanologists. Some that have spent decades studying all sorts of eruptions were forced to rely on expletives to convey their shock. Everyone who cast their eyes on any of these orbital images felt diminutive. Everyone could immediately understand the scale of the disaster. Moments of genuine awe mingle uncomfortably with flecks of horror in a paradoxical emotional admixture.
And as the eruption’s astonishing power became apparent from above, photographs taken on terra firma, those showing Tongan residents mourning the geologic razing of their beloved homes, break our hearts. The sadness we feel seeing crumbled houses and weeping families then gets extrapolated to those satellite images. The scale of this eruption, and its devastation, can be known to us all.
Tonga Volcano Before and After. Images via Planet.
Evocative, factual phrases like “50 million tons of TNT” help unspool the magnitude of the eruption in our minds. But photographs, without a single syllable, shake our soul. Satellite imagery, a still-new technology in our history, gives us a perspective that would have been seen as magic in the recent past. But It also allows us to paint our sympathy and empathy for those suffering on a larger canvas. These images amplify not just our logical understanding of a tragedy, but our emotional comprehension too.
Satellites provide so much more than awe and horror, though. They have also captured our volcanically hyperactive planet at its most beautiful. When volcanic eruptions happen in a harmless manner, the light of their incandescence and ignifluous magic can be trapped within those orbiting technological bottles. And when they erupt disastrously, the images obtained so speedily from our sentinels zipping far above provide volcanologists with vital, and sometimes transformative, scientific data.
In time, Tonga will get back on its feet. The trauma will remain, but just as time moves quickly, so does this remarkably resilient archipelagic kingdom. Almost immediately after the explosion, tsunami, and ashfall of January 15, satellites captured people sweeping volcanic debris off the runways of the main island’s Fuaʻamotu International Airport. Satellites will soon see planes land on these, bringing much-needed aid and emergency responders from afar. We will see ruins cleared away. After that, we will see homes being built. Grey soil suffocating under ash will be washed clean by the rain.
Today satellite images of Tonga are portraying despair. But soon, they will show the world hope.
Note: The header image of this article is sourced from NASA Earth Observatory images by Joshua Stevens and Lauren Dauphin, using CALIPSO data from NASA/CNES, MODIS and VIIRS data from NASA EOSDIS LANCE and GIBS/Worldview and the Suomi National Polar-orbiting Partnership, and GOES imagery courtesy of NOAA and the National Environmental Satellite, Data, and Information Service (NESDIS).