Ground currents to detect a civilization?

[Stephen Tashi]

In a scenario where explorers are trying to detect an active, perhaps subterranean, civilization, is it plausible that they would use equipment that measures ground currents (i.e. actual electrical currents in the terrain)?

With technology that exists today, would we expect to detect a difference in ground currents "out in the middle of nowhere" versus near a town?

 

[russ_watters]

In a scenario where explorers are trying to detect an active, perhaps subterranean, civilization, is it plausible that they would use equipment that measures ground currents (i.e. actual electrical currents in the terrain)?

With technology that exists today, would we expect to detect a difference in ground currents "out in the middle of nowhere" versus near a town?

I can't think of a reason why - what is your reasoning for thinking this should be a thing?

 

[f95toli]

That depends on several factors
If you are asking if there is such a thing as "detecting ground currents" the answer is yes. Surveys to measure these are routinely done before e.g. labs that are meant to house sensitive equipment are built.

However, this is (obviously) only possible (and a potential problem) because we sometimes use ground/earth as a return "conductor". If you use two conductors for you signal there won't be any currently flowing through ground (unless something goes wrong)
A good example from the UK would be return currents from the railroad; these can be a problem even quite some distance from the tracks. Where I work this is somewhat of a problem even though we are approximately about 1000m or so from the tracks; it just so happens that the ground conditions are such that some of the current flows back to its source via the ground underneath the lab.

 

[snorkack]

How does "subterranean civilization" operate without active entrances to ground?
An obvious example of where you do detect the civilization, but not where it is, is mapping a mine. You can observe the mine entrance on ground, but for whatever reasons you cannot walk in and ask the miners for a map. You do not know in which directions from entrance the mine passages go.
From the ground above, what can you do to map mine passages beneath you? To find out which mine passages are deserted and disused, which in active use?

 

[Nik_2213]

Perhaps karst landscape ?? IIRC, the Postogna (sp) and neighbouring cave mega-systems in former Yugoslavia were significantly deepened by the Med's dramatic draw-down during Messinian Event. Just as several rivers running into Med have very deep 'buried valleys' and offshore canyons, the karst water table was affected by the several stages of lowered sea level.

In my 'Chaparral' tale in fiction section, settlers decide to 'dig in' and ride out the decades of dismay from a too-near repeating nova. But, they're in 'Tepuis' with evident signs of mine-heads and adits, spoil dumps etc.

If they were under a vast, carbonate plain, they'd be much harder to find. Especially if not spewing neutrinos etc from eg fusors...

Geo-phys stuff used to map ore bodies, magma chambers etc gets you so far, as do geo-phones and small explosions. I think you'd end up using lots of small robots to swarm-map the maze, relaying data back to surface...

A possible scenario is society / tech implodes, regresses to sorta Neolithic. D&D 'glow-moss' along some routes, a few precious oil / wax lamps, but generations have adapted to darkness, mostly navigating with sonar by click-talking. Diet would be cultivated fungus, blind fish, 'land prawns' (roaches) and, perhaps, sap tapped from super-deep roots of ancient surface / sink-hole trees...