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Earthquake light

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An earthquake light also known as earthquake lightning or earthquake flash is a luminous optical phenomenon that appears in the sky at or near areas of tectonic stress, seismic activity, or volcanic eruptions.[1] There is no broad consensus as to the causes of the phenomenon (or phenomena) involved. The phenomenon differs from disruptions to electrical grids – such as arcing power lines – which can produce bright flashes as a result of ground shaking or hazardous weather conditions.[2][3][4]

Appearance

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One of the first records of earthquake lights is from the 869 Jōgan earthquake, described as "strange lights in the sky" in Nihon Sandai Jitsuroku.[5] The lights are reported to appear while an earthquake is occurring, although there are reports of lights before or after earthquakes, such as reports concerning the 1975 Kalapana earthquake.[6] They are reported to have shapes similar to those of the auroras, with a white to bluish hue, but occasionally they have been reported having a wider color spectrum. The luminosity is reported to be visible for several seconds, but has also been reported to last for tens of minutes. Accounts of viewable distance from the epicenter varies: in the 1930 Idu earthquake, lights were reported up to 110 km (70 mi) from the epicenter.[7] Earthquake lights were reportedly spotted in Tianshui, Gansu, approximately 400 km (250 mi) north-northeast of the 2008 Sichuan earthquake's epicenter.[8]

During the 2003 Colima earthquake in Mexico, colorful lights were seen in the skies for the duration of the earthquake.[citation needed] During the 2007 Peru earthquake lights were seen in the skies above the sea and filmed by many people.[9] The phenomenon was also observed and caught on film during the 2009 L'Aquila[10][11] and the 2010 Chile earthquakes.[12] The phenomenon was also reported around the North Canterbury earthquake in New Zealand, that occurred 1 September 1888. The lights were visible in the morning of 1 September in Reefton, and again on 8 September.[13]

More recent appearances of the phenomenon, along with video footage of the incidents, happened in Napa and Sonoma Counties in California on August 24, 2014,[14] and in Wellington, New Zealand on November 14, 2016, where blue flashes like lightning were seen in the night sky, and recorded on several videos.[15] On September 8, 2017, many people reported such sightings in Mexico City after a 8.2 magnitude earthquake with epicenter 740 km (460 mi) away, near Pijijiapan in the state of Chiapas.[16]

Appearances of the earthquake light seem to occur when the quakes have a high magnitude, generally 5 or higher on the Richter scale.[14] There have also been incidents of yellow, ball-shaped lights appearing before earthquakes.[17]

Instances of this phenomenon appear in videos[18] taken seconds after a 7.1 magnitude earthquake in the city of Acapulco, Mexico, around 20:47 on 7 September 2021. The New York Times reported that "Videos from both Acapulco and Mexico City also showed the night sky lit up with electrical flashes as power lines swayed and buckled."[19]

A recent one was seen in Qinghai Province, China at 01:45 on 8 January 2022. Surveillance video of a local resident captured the moment. During the 2022 Fukushima earthquake the phenomena was captured on video from multiple angles.[20] A 2023 study found the earthquake light coincided with a magnetic disturbance detected by a geomagnetic observatory, and ruled out "the possibility of the flashes being caused by explosions in transformers or power supply facilities" by checking the maintenance reports of regional power stations, none of which had malfunctioned near the location of the observed light.[21]

This phenomenon was observed around 01:18 on 22 September 2022 when a magnitude 6.8 aftershock of the 2022 Michoacán earthquake struck. Social media users including Webcams de México posted videos of blue lights which seemed to be radiating upward. This was reported in Mexico News Daily and included one of the videos.[22]

During the 2023 Turkey–Syria earthquakes, multiple lights appeared continuously in Kahramanmaraş and Hatay provinces.[23] Later that year, blue light flashes were also seen in Agadir during the Marrakesh-Safi earthquake.[24]

Types

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Simplified model of phole propagation within an interplate, orogenic tectonic setting in a subduction zone environment (i.e., Andean‐type). The vertical scale (topographic relief) is exaggerated for clarity. +, positive holes; e′, electrons.[25]

Earthquake lights may be classified into two different groups based on their time of appearance: (1) preseismic earthquake light, which generally occur a few seconds to up to a few weeks prior to an earthquake, and are generally observed closer to the epicenter and (2) coseismic earthquake light, which can occur either near the epicenter ("earthquake‐induced stress"), or at significant distances away from the epicenter during the passage of the seismic wavetrain, in particular during the passage of S waves ("wave‐induced stress").[25]

Earthquake light during the lower magnitude aftershock series seem to be rare.[25]

Possible explanations

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Research into earthquake lights is ongoing; as such, several mechanisms have been proposed.

Some models suggest the generation of earthquake lights involve the ionization of oxygen to oxygen anions by breaking of peroxy bonds in some types of rocks (dolomite, rhyolite, etc.) by the high stress before and during an earthquake.[25] After the ionisation, the ions travel up through the cracks in the rocks. Once they reach the atmosphere these ions can ionise pockets of air, forming plasma that emits light.[26] Lab experiments have validated that some rocks do ionise the oxygen in them when subjected to high stress levels. Research suggests that the angle of the fault is related to the likelihood of earthquake light generation, with subvertical (nearly vertical) faults in rifting environments having the most incidences of earthquake lights.[27]

One hypothesis involves intense electric fields created piezoelectrically by tectonic movements of quartz-containing rocks such as granite.[28]

Another possible explanation is local disruption of the Earth's magnetic field and/or ionosphere in the region of tectonic stress, resulting in the observed glow effects either from ionospheric radiative recombination at lower altitudes and greater atmospheric pressure or as aurora. However, the effect is clearly not pronounced or notably observed at all earthquake events and is yet to be directly experimentally verified.[29]

During the American Physical Society's 2014 March meeting, research was provided that gave a possible explanation for the reason why bright lights sometimes appear during an earthquake. The research stated that when two layers of the same material rub against each other, voltage is generated. The researcher, Troy Shinbrot of Rutgers University, conducted experiments with different types of grains to mimic the crust of the Earth and emulated the occurrence of earthquakes. He reported that "when the grains split open, they measured a positive voltage spike, and when the split closed, a negative spike." The crack allows the voltage to discharge into the air which then electrifies the air and creates a bright electrical light when it does so. According to Shinbrot, they have produced these voltage spikes every single time with every material tested. While the reason for such an occurrence was not provided, Shinbrot referenced the phenomenon of triboluminescence. Researchers hope that by getting to the bottom of this phenomenon, it will provide more information that will allow seismologists to better predict earthquakes.[30][31][32]

Skepticism

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In 2016, podcaster Brian Dunning said he was skeptical that the phenomenon even existed, citing a lack of direct evidence. There is also a "staggering volume of literature... hardly any of these papers agree on anything... I'm forced to wonder how many of these eager researchers are familiar with Hyman's Categorical Imperative 'Do not try to explain something until you are sure there is something to be explained'."[33]

In 2016, freelance writer Robert Sheaffer wrote that skeptics and science bloggers should be more skeptical of the phenomenon. Sheaffer on his Bad UFO blog shows examples of what people claim are earthquake lights, then he shows photos of iridescent clouds which appear to be the same. He states that "It's truly remarkable how mutable "earthquake lights" are. Sometimes they look like small globes, climbing up a mountain. Sometimes they look like flashes of lightning. Other times they look exactly like iridescent clouds. Earthquake lights can look like anything at all, when you are avidly seeking evidence for them."[34]

See also

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References

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  1. ^ Whitehead, Neil Evan; Ulusoy, Ü. (17 December 2015). "Origin of Earthquake Light Associated with Earthquakes in Christchurch, New Zealand, 2010–2011" (PDF). Earth Sciences Research Journal. 19 (2): 113–120. doi:10.15446/esrj.v19n2.47000.
  2. ^ "What are earthquake lights? | U.S. Geological Survey". United States Geological Survey. Retrieved 17 January 2023.
  3. ^ Bressan, David. "'Light Shows' Filmed During Mexico Quake Are Neither Earthquake Lights Nor UFOs". Forbes. Retrieved 2023-01-17.
  4. ^ "Power Flashes: Arcing power lines during storm events". stormhighway.com. Retrieved 2023-01-17.
  5. ^ Clarke, Richard A.; Eddy, R. P. (2017). Warnings: Finding Cassandras to stop catastrophe. Harper Collins. p. 77.
  6. ^ "November 29, 1975 Kalapana Earthquake". Hvo.wr.usgs.gov. Retrieved 2010-09-13.
  7. ^ Lane, F. W. The Elements Rage (David & Charles 1966), pp. 175–76
  8. ^ Paul Simons (2008-03-15). "Glowing lights around an earthquake's epicenter". The Times. London. Archived from the original on October 8, 2008. Retrieved 2008-05-20.
  9. ^ "Study homes in on the cause of earthquake light". Physicsworld.com. 2014-01-14. Retrieved 2016-05-05.
  10. ^ Fidani, C. (2010). "The earthquake lights (EQL) of the 6 April 2009 Aquila earthquake, in Central Italy". Natural Hazards and Earth System Sciences. 10 (5): 967–78. Bibcode:2010NHESS..10..967F. doi:10.5194/nhess-10-967-2010.
  11. ^ Fidani, C. (March 2012). "Statistical and spectral properties of the L'Aquila EQL in 2009". Bollettino di Geofisica Teorica ed Applicata. 53 (1): 135–46. doi:10.4430/bgta0034. Archived from the original on 2015-05-19.
  12. ^ "Registran enormes luces en el cielo durante terremoto de 88 grados de magnitud que destruyo Chile" [Recorded huge lights in the sky during the earthquake of 8.8 magnitude that destroyed Chile] (in Spanish). Peru Online. February 28, 2010. Archived from the original on March 1, 2010.
  13. ^ Hutton (1888). "The Earthquake in the Aimuri". Transactions and Proceedings of the Royal Society of New Zealand. 21: 269–353.
  14. ^ a b Carter, Lori (25 August 2014). "Did you see flashes? Yep, an earthquake can create 'em (w/video)". Press Democrat. Press Democrat. Retrieved 9 September 2014.
  15. ^ "Wellington's sky turns blue at midnight as quakes collide, produce rare tectonic plate phenomenon". 1News.co.nz. 1News. November 14, 2016. Retrieved August 15, 2022.
  16. ^ "¿Qué eran las luces que se vieron durante el sismo?" [What were the lights that were seen during the earthquake?]. El Universal (in Spanish). Retrieved 8 September 2017.
  17. ^ Howard, Brian Clark. "Bizarre Earthquake Lights Finally Explained". National Geographic. Archived from the original on January 9, 2014. Retrieved 25 August 2014.
  18. ^ "Videos: Rare earthquake lights on Acapulco Mexico". Axency.com. 8 September 2021. Retrieved 13 September 2021.
  19. ^ Lopez, Oscar (2021-09-08). "Major Quake Shakes Acapulco, Mexico City". The New York Times. ISSN 0362-4331. Retrieved 2021-09-08.
  20. ^ "'Earthquake light' appears in sky above Japanese city – video". The Guardian. 16 March 2022. Retrieved 7 May 2022.
  21. ^ Xie, Busheng; Wu, Lixin; Mao, Wenfei; Wang, Ziqing; Sun, Licheng; Xu, Youyou (21 October 2023). "Horizontal Magnetic Anomaly Accompanying the Co-Seismic Earthquake Light of the M7.3 Fukushima Earthquake of 16 March 2022: Phenomenon and Mechanism". Remote Sensing. 15 (20): 5052. Bibcode:2023RemS...15.5052X. doi:10.3390/rs15205052. ISSN 2072-4292.
  22. ^ Davies, Peter (2022-09-22). "6.9 magnitude earthquake rocks Michoacán; 2 deaths reported". Mexico News Daily. Retrieved 2022-09-23.
  23. ^ "Dashcam footage captures moment fresh earthquake hits Turkey – video". The Guardian. 20 February 2023.
  24. ^ "Mysterious blue light flashes moments before Morocco earthquake". Al Bawaba. 10 September 2023.
  25. ^ a b c d Thériault, Robert; St-Laurent, France; Freund, Friedemann T.; Derr, John S. (2014-01-01). "Prevalence of Earthquake Lights Associated with Rift Environments". Seismological Research Letters. 85 (1): 159–178. Bibcode:2014SeiRL..85..159T. doi:10.1785/0220130059. ISSN 0895-0695.
  26. ^ Stromberg, Joseph (2014-01-02). "Why Do Lights Sometimes Appear in the Sky During An Earthquake?". Smithsonian Magazine. Retrieved 2021-10-11.
  27. ^ Thériault, Robert; St-Laurent, France; Freund, Friedemann T.; Derr, John S. (2014). "Prevalence of Earthquake Lights Associated with Rift Environments". Seismological Research Letters. 85 (1). Seismological Society of America: 159–78. Bibcode:2014SeiRL..85..159T. doi:10.1785/0220130059. ISSN 0895-0695.
  28. ^ Takaki, Shunji; Ikeya, Motoji (1998). "A Dark Discharge Model of Earthquake Lightning". Japanese Journal of Applied Physics. 37 (9A): 5016–20. Bibcode:1998JaJAP..37.5016T. doi:10.1143/JJAP.37.5016. S2CID 119878878.
  29. ^ "'Restless Earth' May Give Advance Notice of Large Earthquakes" (Press release). NASA. December 7, 2001. Archived from the original on March 16, 2010. Retrieved January 4, 2014.
  30. ^ Choi, Charles (26 February 2014). "Mysterious Flashing 'Earthquake Lights' Maybe Explained". livescience. Retrieved 9 September 2014.
  31. ^ Kim, Meeri. "Experiments at Rutgers lend credence to existence of 'earthquake lights'". The Washington Post. Retrieved 9 September 2014.
  32. ^ Luntz, Stephen (7 March 2014). "Clue To Mysterious Lights That Appear Before Earthquakes". Iflscience!. Retrieved 9 September 2014.
  33. ^ Dunning, Brian. "Skeptoid #534: Earthquake Lights: Do They Exist?". Skeptoid. Retrieved 1 September 2016.
  34. ^ Sheaffer, Robert (7 January 2014). "Skeptics and Claims of "Earthquake Lights"". Bad UFOs: Skepticism, UFOs, and The Universe. Blogger. Retrieved 6 September 2016.
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