Deep Ochre: Deep Background on Arsia Mons
With the emerging crisis in the Tharsis region, we provide the first installment of a historical primer on the worsening socio-geotechnical situation.
Note: Stay up to date with our latest dispatch from the Martian Outlands here and learn more about our mission here.
As Martian volcanoes go, Arsia Mons is overshadowed by the unthinkable size of its neighbor, Olympus Mons – the largest volcano in the solar system. An old outlander working the Tharsis route in the earliest days of peopling liked to say an eruption of Olympus Mons would be like if the entire nation of France were a swollen bloody pimple that God decided to pop one day. The oldest Outlanders had a way with illustrations that were at once geographically accurate, nauseating and offensive to at least one nationality.
And the image of l’Hexagone erupting in a massive mess of blood and pus does at least present a comparable scale, as the resilient nation has roughly the same diameter as Olympus Mons. But literally building upward on this comparison, such a zit would be an absolutely grotesque growth since Olympus Mons is over twice the altitude of Mount Everest.
Let’s take the disgusting comparison even further: imagine one half of Mars as a human face, and Olympus Mons would occupy nearly 18 percent of it. So our volcanic pimple would take up nearly one fifth of this poor hypothetical person’s planetary profile and it would be swollen to a height that overshadows the nose.
Arsia Mons is not nearly as massive as Olympus Mons. And yet, awesome Arsia is still about as wide as the state of Utah. Picture a single volcano covering everything in between Nevada and Colorado from east to west, from the Great Salt Lake to Lake Powell north to south. And of course, the whole thing rises to an elevation of over 60,000 feet, twice as high as Everest.
This gorgeous rusty mound is where humanity installed the industrial heart of its new venture on Mars.
It seemed to make sense at the time. Arsia is less intimidating than Olympus, which soars 16 miles high, and ice can be found at a variety of elevations. The lava tubes below Arsia also proved more accessible and suitable to habitation in the early years.
But when accidents or miscalculations happen, all that ice can become a deluge and the tubes perfect channels for a devastating flash flood.
No escape
Back on Earth, one of the earliest signs the climate tide was turning for the worse was the rash of glacial lake outburst floods (GLOFs) in the Himalayas and the Andes and even in the Alps and Rockies. As the high glaciers melted, what were once small lakes and trickling tributaries at their toes bloated into swollen reservoirs and relentless torrents. The insult added to this injury was the destabilization of the glacier itself that drastically increased calving, ice and rockfall events. Huge chunks of mass falling into oversized lakes below triggered surprisingly voluminous tsunamis that would rip down high canyons, scraping away much of the life that had established itself in the valleys below. Vegetation, livestock, villages, dams and just about anything else could be washed away by a powerful outburst flood.
And such catastrophes all took place above ground, where all that water theoretically had some room to spread out. At Arsia Mons this hydrological violence ran its course through subterranean settlements were there was no such relief. The weak gravity of Mars is still plenty powerful enough to pull a million drips downward until they form into larger moulins emptying into one of millions of holes or fissures in the mountain’s Swiss cheese foundation. Eventually it finds its way into volcanic air pockets, including some occupied voids.
The worst such event here came relatively early. Long before warming up the planet or terraforming was part of the discussion. It was a pretty simple engineering mistake… relying too heavily on old and outdated scans of the region, some really primitive MRO data that hadn’t yet been replaced by GeoMars scans. All the automation in two worlds and still plenty of room for human error.
Anyway, an early residential encampment was setup inside a lava tube below the glacier that had been cataloged as clear of all glacial toes and flagged as safe. The pioneers thought they were living below dry regolith, but actually the porous rock over their heads was thin. Above a slight layer of lava rock was a small, dark cavity below thousands of tons of ice, which must have frozen solid before that air pocket was created by some sort of collapse of the frail pumice… maybe from a weak marsquake of some sort.
Maybe you see where this is going already. Residential encampments put out a certain amount of waste heat and gas, which was enough to begin to melt and weaken that frozen shelf, leading it to collapse down into that void, through the thin layer of regolith and, well… thousand of tons of ice falling on your home with no warning – I think you get the picture.
There were no survivors among the engineers and their families who were subterranean at the time of the collapse. It was the first such tragedy of the peopling period and actually remains the event with the single highest death toll on Mars to date.
But the response to this historic failing — or rather the response to the response — leaves much to be desired. Today, with tensions building and commmunications breaking down in the Outlands, there is a strong sense among many, including this correspondent, that on Mars as on Earth, the disasters of the past are mere prologue for headlining events that could produce the worst sort of spectacle.