In California’s Imperial Valley—an expanse of desert where geothermal energy, agriculture, and quiet rural towns coexist—lies one of the most unusual natural features in the United States. It is known as the Niland Geyser, though the term “geyser” is somewhat misleading. This phenomenon is in fact a moving mud pot, the first in recorded history known to migrate at a measurable pace across the landscape. Its slow but relentless movement has reshaped infrastructure, challenged engineers, and drawn worldwide scientific attention.
What Exactly Is the Niland Geyser?
Mud pots are a common feature in geothermal regions. They form when heated groundwater rises through fine sediments and mixes with gases such as carbon dioxide to create warm, bubbling pools of mud. Unlike geysers, which erupt from pressure build-up, mud pots quietly burble and churn.
The Niland Geyser, located near the town of Niland and close to the Salton Sea, is unique because it has been slowly moving westward since around 2015. While typical mud pots stay fixed in place, this one behaves almost like a geological glacier.
Researchers believe the geyser’s movement is driven by the flow of CO₂-rich groundwater, the same geologic forces that formed the Salton Trough, one of North America’s most geothermally active zones.
The Niland Geyser is actually not a geyser in the true sense of the term, because it is not heated by the Earth’s interior. The bubbling water, mud and gas remains at a tepid 27 degrees centigrade. The geyser’s movement is driven by the flow of CO₂-rich groundwater, the same geologic forces that formed the Salton Trough, one of North America’s most geothermally active zones. However, it emits a staggering 40,000 gallons of water per day, far more than a typical mud pot, leading some experts to classify it as a mud spring.
A History of Slow but Significant Movement
Niland Geyser is one of around 30 mud pots and mud volcanoes located near the south-eastern shore of the Salton Sea. Although the mud pot had existed for decades, it was only in 2015 or 2016, possibly following seismic activity, the geyser began to move unprecedentedly south-west. Initially it moved at around 10 to 20 feet per year, but later accelerated to 10 feet per month by 2022.
As it moved, it brought with it a set of costly problems. In 2018, the geyser approached Union Pacific railroad tracks, threatening a major freight line used to transport goods from California’s ports to the rest of the United States. The railroad was forced to install a temporary bridge and reroute tracks, costing millions of dollars. At the same time, State Route 111, a key highway connecting agricultural towns to the wider region, lay directly in the geyser’s path. Portions of the road had to be closed and rebuilt in a new alignment. Underground fiber-optic cables, gas lines, and irrigation systems faced repeated disruptions as the mud pot undermined anything in its way.
Why Is This Mud Pot Moving?
Scientists still do not know what is causing the Niland Geyser to inch its way across California. They are certain, however, that the movement is not linked to increased seismic activity. Ken Hudnut, a research geophysicist with the U.S. Geological Survey, said that the San Andreas Fault is closely monitored and shows no signs of an impending major earthquake.
Geologists David Lynch and Travis Deane, in an article written for The American Society of Civil Engineer, have hypothesized that the carbon dioxide is travelling to the surface via a tilted route, with the upper side of the channel gradually being eroded by the water and gas and the lower side building up as sediment falls onto it.
The process described is known as the sapping model and could explain the horizontal movement of the spring.
Beneath the mud pot there may be a tube-like channel (a “soil pipe”) carved through soft sediments. Water and gas move upward through this pipe, and gravity causes erosion inside it. Even though the Niland Geyser is driven upward by CO₂ gas bubbles, both this mechanism and other potential mechanisms involve sediment inside the pipe eroding and collapsing, which can force the water to find a new path.
If the underground pipe is slanted, erosion causes the upper part of the pipe (higher end) to lose sediment as it collapses, while the lower part of the pipe (downhill end) receives that sediment. This uneven erosion gradually shifts where the pipe opens at the surface. As the underground flow is redirected, the surface spring shifts too—hence the mud pot appears to “move.”
In this model, the mud pot keeps migrating until it reaches the spot on the surface directly above the deep underground source of water and gas. When it reaches that point, the movement would stop.
It is also possible that the CO 2 source itself is moving along a northeast-striking fault, or that the spring is moving along a playa fracture. These fissures are the result of desiccation cracking when a shallow lake dries up, in this case Lake Cahuilla. These fractures are usually linear and are like mud cracks but larger. Over time they fill with sediment that tends to be less hardened than the surrounding lake bed. When ground or spring water pushed from below, they tend to reach the surface through such a crack.
As of recent observations, the Niland Geyser continues to migrate, though the rate fluctuates. Efforts to contain it, such as installing subsurface barriers, pumping out water, or digging diversion trenches, have had only temporary effects.
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