Earthquake lights linked to rift environments, subvertical faults

Jan 02, 2014
Earthquake lights from Tagish Lake, Yukon-Alaska border region, around the 1st of July, probably 1972 or 1973 (exact date unknown). Estimated size: 1m diameter. Closest orbs slowly drifted up the mountain to join the more distant ones. Credit: Jim Conacher

Rare earthquake lights are more likely to occur on or near rift environments, where subvertical faults allow stress-induced electrical currents to flow rapidly to the surface, according to a new study published in the Jan./Feb. issue of Seismological Research Letters.

From the early days of seismology, the luminous phenomena associated with some earthquakes have intrigued scholars. Earthquake lights (EQL) appear before or during earthquakes, but rarely after.

EQL take a variety of forms, including spheres of light floating through the air. Seconds before the 2009 L'Aquila, Italy earthquake struck, pedestrians saw 10-centimeter high flames of light flickering above the stone-paved Francesco Crispi Avenue in the town's historical city center. On Nov. 12, 1988, a bright purple-pink globe of light moved through the sky along the St. Lawrence River near the city of Quebec, 11 days before a powerful quake. And in 1906, about 100 km northwest of San Francisco, a couple saw streams of light running along the ground two nights preceding that region's great earthquake.

Continental rift environments now appear to be the common factor associated with EQL. In a detailed study of 65 documented EQL cases since 1600 A.D., 85 percent appeared spatially on or near rifts, and 97 percent appeared adjacent to subvertical faults (a rift, a graben, strike-slip or transform fault). Intraplate faults are associated with just 5 percent of Earth's seismic activity, but 97 percent of documented cases of earthquake lights.

"The numbers are striking and unexpected," said Robert Thériault, a geologist with the Ministère des Ressources Naturelles of Québec, who, along with colleagues, culled centuries of literature references, limiting the cases in this study to 65 of the best-documented events in the Americas and Europe.

"We don't know quite yet why more earthquake light events are related to rift environments than other types of faults," said Thériault, "but unlike other faults that may dip at a 30-35 degree angle, such as in subduction zones, subvertical faults characterize the rift environments in these cases."

Two of the 65 EQL events are associated with subduction zones, but Thériault suggests there may be an unknown subvertical fault present. "We may not know the fault distribution beneath the ground," said Thériault. "We have some idea of surface structures, but sedimentary layers or water may obscure the underlying fault structure."

While the 65 earthquakes ranged in magnitude, from M 3.6 to 9.2, 80 percent were greater than M 5.0. The EQL varied in shape and extent, though most commonly appeared as globular luminous masses, either stationary or moving, as atmospheric illuminations or as flame-like luminosities issuing from the ground.

Timing and distance to the epicenter vary widely. Most EQL are seen before and/or during an earthquake, but rarely after, suggesting to the authors that the processes responsible for EQL formation are related to a rapid build-up of stress prior to fault rupture and rapid local stress changes during the propagation of the seismic waves. Stress-activated mobile electronic charge carriers, termed positive holes, flow swiftly along stress gradients. Upon reaching the surface, they ionize air molecules and generate the observed luminosities.

Eyewitness reports and security cameras captured a large number of light flashes during the 2007 Pisco, Peru M 8.0 earthquake. Together with seismic records obtained on a local university campus, the automatic security camera records allow for an exact timing and location of light flashes that illuminated a large portion of the night sky. The light flashes identified as EQL coincided with the passage of the seismic waves.

Thériault likes the account of a local L'Aquila resident, who, after seeing flashes of light from inside his home two hours before the main shock, rushed his family outside to safety.

"It's one of the very few documented accounts of someone acting on the presence of earthquake lights," said Thériault. "Earthquake lights as a pre-earthquake phenomenon, in combination with other types of parameters that vary prior to seismic activity, may one day help forecast the approach of a major quake," said Thériault.

Explore further: Interpreting the strongest deep earthquake ever observed

More information: Seismological Research Letters, volume 85-1, Jan. – Feb. issue, 2014.

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User comments : 12

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WirelessPhil
4.3 / 5 (3) Jan 02, 2014
This is not some new finding!
This is republished old news.
The news industry has been republishing old news and finding and new news all week!
cantdrive85
1.2 / 5 (6) Jan 02, 2014
Once again, a misunderstanding of the what causes earthquakes results in a misunderstanding of the resulting phenomena. A better understanding of the telluric currents which cause these phenomena and how they are connected to the the Earth's large scale EM field will be necessary before any real discoveries are made.
http://www.thunde...noes.htm

It should be noted that earthquake lights are just one of the phenomena sometimes associated with geologic events.
http://www.scient...eund.pdf
cantdrive85
1 / 5 (5) Jan 02, 2014
Once again, a misunderstanding of the what causes earthquakes results in a misunderstanding of the resulting phenomena. A better understanding of the telluric currents which cause these phenomena and how they are connected to the the Earth's large scale EM field will be necessary before any real discoveries are made.
http://www.thunde...noes.htm


@ cantdrive Skippy, is there anything at all, anywhere, at anytime, any place that isn't caused by thunder bolts and electrician machinists using plasma milling machines?


From where I'm from that is a good indication of a well rounded cosmology. BTW, the article suggests electric currents (first sentence) are the cause, I'm just pointing out those currents must complete a circuit to be possible, most likely telluric currents which are connected to the ionosphere which is connect to the VA belts which is connected to the Sun's plasma etc...
Maggnus
3.7 / 5 (6) Jan 02, 2014
Yea and the leprechaun in my backyard is drinking my beer......
cantdrive85
1 / 5 (3) Jan 02, 2014
Well you had better catch him, then he can pay for your beer with his pot o' gold. Denial and that river in Egypt and all...
aroc91
5 / 5 (1) Jan 03, 2014
BTW, the article suggests electric currents (first sentence) are the cause


Nope. Read it again.

stress-induced electrical currents


Stress-induced currents, not current-induced stress.
cantdrive85
1 / 5 (2) Jan 03, 2014
I know we've gone over this before, but let's review with one more nugget recently discovered by the Van Allen probes. You know, the shin bone connected to the knee bone, the knee bone...
First, the recent piece revealing the electrical connection to the Sun's plasma. The VA probes discovered a series of 7000 parallel electric double layers at the edge of the Van Allen belts. Such a discovery proves a complex electrical connection between Earth and surrounding space environment.
http://physics.ap...s/v6/131
Note the bottom of my linked article, questions asked by the author.
"This prompts new questions: Why are electron acoustic waves and the associated double layers formed? Why do double layers occur in streams of thousands? What conditions allow such large electric potential differences to exist? What drivers of the magnetospheric dynamics can also be found in other astrophysical systems?"

The answers to these questions and more can be found by studying Plasma Cosmology.
cantdrive85
1 / 5 (2) Jan 03, 2014
Anyway, there is an electric connection to the Sun's plasma.
Secondly, the Van Allen belts are connected to the ionosphere.

Ionosphere connected to telluric currents...
http://www.emsev-...3-03.pdf

... connected to the thigh bone...
Scroofinator
4.5 / 5 (2) Jan 03, 2014
Whenever I see a video of these lights it looks like the piezoelectric effect. Like an igniter on a gas grill, the underlying crystalline material might be getting rapidly compressed and releasing an electrical charge.
no fate
2.5 / 5 (2) Jan 03, 2014
Whenever I see a video of these lights it looks like the piezoelectric effect. Like an igniter on a gas grill, the underlying crystalline material might be getting rapidly compressed and releasing an electrical charge.


Good job. I would agree that this is a scaled up version of that effect.
cantdrive85
1 / 5 (2) Jan 03, 2014
Yep, maybe. Then again the crystalline material would be excellent conductor of electricity as well.
RealScience
5 / 5 (2) Jan 03, 2014
Whenever I see a video of these lights it looks like the piezoelectric effect. Like an igniter on a gas grill, the underlying crystalline material might be getting rapidly compressed and releasing an electrical charge.


@Cantdrive - you appear to be referring to the above in your comment:

Yep, maybe. Then again the crystalline material would be excellent conductor of electricity as well.


Quartz is probably the best-known piezoelectric crystal, and quartz it is NOT an "excellent conductor of electricity'.
Please name even one naturally occurring piezoelectric crystal that is an excellent conductor of electricity.

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