Ride the Lightning

[Image: From the paper "Lightning-Induced Remanent [sic] Magnetic Anomalies in Low-Altitude Aeromagnetic Data" by Les P. Beard, Jeannemarie Norton, and Jacob R. Sheehan].

While lightning is on the brain, two random articles I stumbled across this weekend, coming off a nearly 48-hour binge of PDF downloads from various academic journals, refer to two examples of lightning strikes mistaken for, in one case, the discovery of unexploded ordnance in New Mexico and, in another, a minor earthquake in Germany.

In the former, from a paper originally published in 2009 in the Journal of Environmental & Engineering Geophysics, we read how an "airborne magnetic survey for unexploded ordnance," searching for magnetic anomalies in New Mexico, came across a series of inexplicable blips.

[Image: From the paper "Lightning-Induced Remanent [sic] Magnetic Anomalies in Low-Altitude Aeromagnetic Data" by Les P. Beard, Jeannemarie Norton, and Jacob R. Sheehan].

As the paper's abstract explains, however, these magnetic anomalies were not unexploded bombs; they were, in fact, scars in the data most likely induced by lightning strikes.

"Lightning-strike magnetic anomalies are not necessarily rare," the authors explain, "but may be spaced so widely as to make their detection unlikely in a ground survey."

[Image: From the paper "Lightning-Induced Remanent [sic] Magnetic Anomalies in Low-Altitude Aeromagnetic Data" by Les P. Beard, Jeannemarie Norton, and Jacob R. Sheehan].

In other words, surveys elsewhere have likely also recorded lightning strikes as anomalous magnetic formations in the landscape—as physical landforms, whether mineral (metal in the ground) or artificial (in this case, unexploded bombs)—when, in reality, they are side-effects of storms. They are data fossils, caused by lightning.

Lightning here takes on a mapped, physical presence, whereas, in reality—or epistemologically, I should probably say—it is nothing but an event in the sky mistaken for something terrestrial.

[Image: From the paper "Lightning-Induced Remanent [sic] Magnetic Anomalies in Low-Altitude Aeromagnetic Data" by Les P. Beard, Jeannemarie Norton, and Jacob R. Sheehan].

Fascinatingly, the authors hypothesize that this might be because lightning often leaves remnant magnetic effects in the landscape, or "remanent magnetization," for days after the original strike.

It leaves glitches, fingerprints, or marks, in other words—magnetic logos—that can only be read and deciphered by specialty equipment. So, on certain maps, something is there—some aspect of the landscape—but, in reality, it was just a passing electrical event. It was just a cartographic error, a kind of electrical time-object mistaken for the Earth.

Lightning is the original New Aesthetic.

The second paper worth mentioning here describes the fortuitous coincidence of a lightning strike hitting a poplar tree on the grounds of a seismological research station at Cologne University in Germany.

According to a short paper—more like a letter to the editor—published in Seismological Research Letters, we read that the lightning strike "exploded" a poplar tree, whose fragments then "impaled" themselves in the trees around it. This narratively coherent sequence of events was mistaken, however, as a minor earthquake.

[Image: The stricken poplar tree, from "Seismological Analysis of a Lightning Strike" by Klaus-G. Hinzen].

In the words of Klaus-G. Hinzen, the paper's author, "the electrical field of the lightning induced a signal, most likely in the seismometer cable, that the instrument electronics interpreted as the command to start calibration." The equipment thus began to record as if a "real" seismic event was taking place. However, Hinzen goes on to explain, "the signal of the lightning and the thunder is visible after the application of a highpass filter"—that is, you can filter out the Earth from data and you will find pure sky.

So there was no earthquake—at least not tectonically speaking—but the precise moment at which an event in the sky (lightning and thunder) intersected with a landscape on the ground (the poplar tree outside the laboratory) was both recorded as and equipmentally mistaken for an earthquake.

There's no point in going on about this at great length, but I was interested to see how, in both cases, a diaphanous but barbed moment of electricity in the atmosphere—like a silk lace given thorns—could be misinterpreted by machines constructed for reading the earth. Or, putting this in mythological terms, the sky temporarily deceived the earth by way of electricity, sneaking past the ground's immuno-seismic system and entering human history as something apparently terrestrial, a measurable feature in the landscape.

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Blogger a progressive crank said...

The exploded tree reminds me of one I saw many years ago in the Everglades. The story was that the tree was struck such that the sap instantly turned to steam and blew all the bark off, leaving a smooth barkless trunk riddled with holes where the sublimated sap forced its way out. Lightning boiling sap is apparently not uncommon but losing all the bark made this one unusual, perhaps unique.

September 02, 2013 12:51 AM  
Blogger Geoff Manaugh said...

Thanks, Crank - great story. It was like a tea kettle, steaming away in the swamp.

September 02, 2013 6:27 PM  

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