In Azerbaijan, there’s a mountain that’s been burning for about 4,000 years. Not metaphorically—actually burning, with flames licking out of the ground like the earth forgot to turn off the stove. But here’s the thing: it’s not a volcano. Not in the molten rock, Pompeii-destroying sense anyway.
Mud volcanoes are what happens when the planet decides to get weird with pressure and chemistry instead of just going full pyroclastic flow on everyone. They’re scattered across places like Azerbaijan, where roughly 400 of them dot the landscape, or the Salton Sea in California, where they bubble away in eerie silence. Some are tiny—barely knee-high mounds that gurgle like a toddler’s science experiment. Others, like Lokbatan near Baku, tower at 400 meters and occasionally explode with flames that can be seen from space.
Wait—maybe “volcano” is the wrong word entirely.
The mechanism is almost disappointingly simple until you think about it for more than five seconds. Underground, sedimentary layers get compressed over milenia. Water and gases—mostly methane—build up in pockets. Pressure mounts. Eventually, something’s got to give, and what gives is a slurry of mud, water, and gas that punches through to the surface. The result looks like a miniature volcano, complete with cone and crater, except instead of lava you get cold, grey sludge that smells faintly of rotten eggs and broken dreams.
When the Earth Decides to Burp Methane and Nobody Knows Why
Turns out these things are climate wildcards that scientists are only starting to take seriously. A 2006 study estimated that mud volcanoes globally emit about 6 to 9 million tons of methane annually—roughly equivalent to the emissions from all of Canada’s cattle. That’s not nothing when you’re trying to balance a planetary carbon budget that’s already teetering like a drunk accountant.
The Lusi mud volcano in Indonesia is probably the most catastrophic modern example, and it wasn’t even natural. In 2006, a gas exploration well blew out near Sidoarjo, and mud started erupting at a rate of 180,000 cubic meters per day. Sixteen years later, it’s still going. The flow has buried entire villages—twelve of them—displacing nearly 60,000 people. The mud lake now covers about 7 square kilometers, and geologists estimate it might continue for another 25 years. Its basically an industrial accident that became a geological feature.
But natural mud volcanoes have their own drama. The Dashgil eruption in Azerbaijan in 2001 shot flames 15 meters into the air. In 2018, one near the Caspian Sea erupted with such force it launched rocks several kilometers away.
The Cold Fire Problem That Makes Absolutely No Sense Until It Does
Here’s where it gets genuinely strange: some mud volcanoes periodically ignite. The methane bubbling up catches fire, and suddenly you have flames emerging from what looks like a muddy puddle. Azerbaijan’s Yanar Dag (“burning mountain”) has been aflame continuously since at least the 1950s, possibly centuries longer. Medieval travelers wrote about eternal fires in the region, which makes sense when you realize the country sits on massive natural gas reserves that occasionally find creative exit routes.
The temperature differential is surreal—liquid mud at ambient temperature surrounded by flames hot enough to roast meat. It violates every instinct about how fire is supposed to work.
Marine mud volcanoes add another layer of weirdness. The Håkon Mosby mud volcano, sitting 1,250 meters below the Barents Sea, creates its own ecosystem. Bacterial mats thrive on the methane seepage, supporting communities of tubeworms and other creatures that have no business existing in such a hostile environment. Scientists discovered it in 1989, and it’s been confounding marine biologists ever since with its combination of toxic chemistry and thriving life.
Trinidad has over 30 active mud volcanoes, including the Devil’s Woodyard, where local legend holds that the bubbling mud is a portal to hell. The scientific explanation—compressional tectonics forcing fluid through fault lines—is arguably less interesting than the folklore, though geologists would disagree.
What makes mud volcanoes particularly maddening for researchers is their unpredictability. Unlike magmatic volcanos, which often give warning signs through seismic activity, mud volcanoes can sit dormant for years and then suddenly erupt with almost no preamble. The Lokbatan volcano near Baku was quiet for decades before erupting in 2001, then again in 2017. Each time, scientists scrambled to measure and understand, only to watch it return to gurgling dormancy.
And we’re still finding new ones—a 2020 survey identified previously unknown mud volcano fields off the coast of Norway, suggesting we’ve barely scratched the surface of understanding their global distribution and impact.
