While it’s almost certain that the U.S. has a number of top secret underground military bases in the U.S. and probably elsewhere in the world, it is interesting to observe what technologies the U.S. military uses to try to locate buried facilities built by other nations.
Some clues to what sort of technology the U.S. uses to uncover such underground bases is provided in a May 2000 paper written by Lieutenant Colonel Eric Sepp at the Air War College at Maxwell Air Force Base. In the paper, Colonel Sepp examined some lessons learned by the military in conflicts such as the Persian Gulf War, and what sort of technologies were developed by the military as a consequence.
Those technologies are used to detect the construction or presence of underground facilities, and even how those facilities are set up and what they’re being used for.
The sort of underground sites examined in the paper are those that are typically buried “hundreds of feet below the surface”, or into the side of a mountain, and might also be protected by walls of solid rock.
A Design for Impenetrable Bases
Not only does the report take a look at technologies that the U.S. uses to detect such underground bases, but also how the U.S. military defines its own “well-protected” bases.
One clue is on page 6, where Sepp explains that studies conducted by military contractors provided a definition of what a nearly indestructible base would look like.
“Studies by the RAND Corporation and MITRE Corporation suggest that facilities located at depths of 2,000 feet beneath the surface are essentially invulnerable.”
Interestingly, Sepp’s description of such a “perfect” location for such a facility provides adventurers seeking to locate such facilities with the perfect clues as to where to look. Not only do military builders look for locations with the most “overburden” – such as mountains – but also seek out the following characteristics of the land:
–> A level of dry, solid rock that is nearly horizontal and at least 100 feet thick.
–> The presence of water. Sepp writes, “An aquifer would be ideal since it could also be tapped for water and contribute to the self-sufficiency of the facility.”
–> Examples of rock stratum ideal for such a facility include “structurally sound Limestone and granite”.
–> Using long tunnels or blast doors in order to force the collapse of entry tunnels in the event of a military attack and a blast from the outside of the facility. Sepp reveals that the ideal design ratio is 500 feet of tunnel length for every foot of tunnel diameter.
Sepp points out that the use of long tunnels also makes it very difficult for any external observers of the tunnel entrances to judge exactly where the facility is located.
What Underground Bases Probably Look Like
Sepp also points out that the MITRE Corporation study found that such a structure being built underneath a rock cavity should consist of “chambers” no larger than 40 feet wide and 45 feet high.
Each of those chambers would then be connected to one another via a “matrix of tunnels.”
Other methods that the military uses to hide the existence of such underground bases include:
–> Avoiding the use of “manmade patterns”, like vents and entrances that use square or triangular shapes.
–> Placing entrances or vents in areas of high vegetation with a high IR signature.
–> Painting surface equipment and structures in “subdued tones” to reduce the reflectivity of those objects, making them harder for satellite imagery to pick up.
–> Placing decoys – fake exhaust vents, antenna arrays and even entrances to trick foreign satellite observers into believing that the presence of the underground base is somewhere that it isn’t.
–> Insulating areas and vents near the surface of the Earth so as to minimize its thermal signature.
Not only are these issues that the military must consider when it is attempting to build underground facilities that are undetectable to foreign enemies, but they are also issues that the military must keep in mind when trying to detect foreign buried facilities!
The process of trying to locate such underground military bases in other parts of the world is aptly described in this Air Force paper as a process of “prospecting”.
Prospecting for Underground Bases
Scientific methods that are available for the detection of underground bases include gravity field mapping, magnetic field mapping, ground penetrating radar, seismic sensors, electromagnetic sensors, electrical conductivity sensors and radioactivity sensors.
One of the most impressive forms of prospecting that could also be used by treasure hunters or archaeologists to identify deeply buried underground structures is gravity field mapping.
This involves the use of gravity surveys using a gravimeter – meter by meter – to map out the gravity vectors in an area. The force of gravity tends to change in areas where the density of the subterranean features change, allowing a crafty prospector to detect such changes, and identify a possible cavity under the Earth.
In fact, Sepp suggests that the Air Force uses this very method to detect underground facilities, by using “a concept for locating underground facilities [which] involves the integration of a gradiometer, GPS receiver, and the ability to transmit raw gradiometer data to an airborne platform, such as an uninhabited aerial vehicle (UAV).”
Of course, satellites and human intelligence will always remain valuable tools to identify such facilities, but considering the increased use of drones for many military operations across the world, it seems very likely that such unmanned drones will also be used far more often to detect deeply buried facilities through the use of gravimeter surveying technologies.
Considering that this report was actually written and published in 2000, it is conceivable that the airborne gravimeter detection capabilities have advanced significantly over the next decade, and that the U.S. military is now highly capable of using drones to identify secret underground bases around the world.