Mud Pots on the Move
OSW - Niland, Imperial County, California March 23, 2019
After months of inquiries, SDAG was granted access to a Union Pacific Railroad property where a giant mud pot forced the relocation of train tracks and continues to threaten existing tracks,
a petroleum pipeline, a fiber optic cable and State Highway 111.
The Union Pacific Railroad's southern California to Texas mainline parallels the eastern shore of the Salton Sea, where approximately 60 to 80 trains per day carry international goods from
Asia to the interior United States.
Dave Lynch of Caltech met us to provide safety rules and give a summary of recent mud pot activity.
We then followed Dave across the railroad tracks to view a 23-foot deep sinkhole that appeared to be furiously boiling.
Although geothermal activity is present in this region, the water in the pit is actually at ambient temperature, and the disturbance seen is caused by CO2 bubbling up through groundwater.
The mud pot is currently being dewatered as a means to try to control it, and approximately 40,000 gallons of water are removed every day!
CO2 is present all throughout this area, resulting from the decomposition of calcium carbonate sediments spurred by geothermal activity deep below the surface.
The CO2 moves up through the sediments but is only obvious in areas where groundwater is present.
Where mud pots bubble up the water has been pushed up to the surface and in some cases the sediments collapse.
This mud pot first appeared in 1953 and was a typical, stationary mudpot until some time around 2007 when it began to move westward.
Its progress was slow at first, but since April of 2018 it has grown increasingly mobile and now has moved
240 feet from its original site.
No one knows exactly why these mud pots are on the move.
The USGS and NASA's Jet Propulsion Laboratory are assisting with research, and Dave has some theories, but we will have to wait until they are published.
Look for Dave's article in the June issue of Civil Engineering.
After the visit to the Union Pacific site, a smaller group of geologists headed out to the mud volcanoes of the Davis-Schrimpf Seep Field.
A geothermal plant visible nearby confirms the presence of deep geothermal activity - a result of shallow magma intrusions associated with a spreading center at the southern end of the San Andreas Fault.
Temperatures at depth can reach 300oC and higher, although by the time the CO2- laden water reaches the surface it is often at ambient temperatures or slightly warmer.
The heat, however, helps to break down the sediments, releasing the CO2 gas.
The result is a unique geological phenomenon of bubbling, gurgling, mud-spurting volcanoes - a delight for geologists and all!
Provided by: Jennifer Morton
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