An earthquake light is an unusual luminous aerial phenomenon, similar in appearance to the aurora borealis, that allegedly appears in the sky at or near areas of tectonic stress, seismic activity or volcanic eruptions. Scientific evidence for the presence of lights is sketchy, given that there are few references documenting the phenomenon. Image File history File links Merge-arrows. ... Earthquake clouds are clouds claimed to be signs of imminent earthquakes. ... Aurora borealis Polar aurorae are optical phenomena characterized by colorful displays of light in the night sky. ... ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...

Appearance

The lights are most evident in the middle period of an earthquake, although there are reports of lights that occurred after or even before the earthquake, as in the 1976 Tangshan earthquake.^{[citation needed]} They usually have shapes similar to those of the auroras with white to bluish hue, but occasionally they have been reported to have a wider color spectrum.^{[citation needed][citation needed]} The luminosity is typically visible for several seconds, but there have been cases in which they lasted tens of minutes. In the 1930 Idu earthquake, lights were reported up to 70 miles from the epicentre.^[1], although most lights are not so far away. Many buildings were flattened into rubble when the earthquake hit. ... The Aurora Borealis, or Northern Lights, shines above Bear Lake Aurora Borealis as seen over Canada at 11,000m (36,000 feet) Red and green Aurora in Fairbanks, Alaska Aurora Borealis redirects here. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ...

There have also been cases in which electromagnetic waves caused by the earthquake interfered with radio transmissions, such as during the Great Chilean Earthquake of 1960.^{[citation needed]} Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ... Map showing the areas affected by the tsunami The Great Chilean Earthquake or Valdivian Earthquake (Terremoto de Valdivia in Spanish) of 22 May 1960 is the most intense earthquake ever recorded, rating a 9. ... Year 1960 (MCMLX) was a leap year starting on Friday (link will display full calendar) of the Gregorian calendar. ...

Distinguishing earthquake lights from other transient optical phenomena can be difficult during the chaos of a tremor. For example, a bluish-white flashes that are accompanied by loud bangs or hissing during an earthquake are more likely the result of electrical arcing in power lines or transformers.

History

Records of earthquakes that were accompanied by lights can be found as far back as 373 BC in ancient Greek writings, that "immense columns of flame" foretold the earthquake that destroyed the cities of Helike and Boura (references needed). However, even in the early 20th century they were still considered a myth, despite an investigation of lights seen during the 1930 Idu earthquake by researchers from Tokyo University,^[2] until photographs of actual lights were taken in Japan in the 1960s. Centuries: 5th century BC - 4th century BC - 3rd century BC Decades: 420s BC 410s BC 400s BC 390s BC 380s BC - 370s BC - 360s BC 350s BC 340s BC 330s BC 320s BC 378 BC 377 BC 376 BC 375 BC 374 BC - 373 BC - 372 BC 371 BC 370... Helike (Greek: pron. ... ancient Achaia Boura (also Bura, Bira; Greek: ), was an ancient city of Achaea, Greece, one of the 12 cities of the Achaean League. ... (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the... For other uses, see Mythology (disambiguation). ... The Yasuda Auditorium on the University of Tokyos Hongo Campus. ... Year 1960 (MCMLX) was a leap year starting on Friday (link will display full calendar) of the Gregorian calendar. ...

The night before the 1976 Tangshan earthquake, many people in Tangshan reported seeing strange lights.^{[citation needed]} Many buildings were flattened into rubble when the earthquake hit. ... Tangshan (Chinese: 唐山市; Pinyin: Tángshān shì) is a prefecture-level city in Hebei province, Peoples Republic of China. ...

In Peru's earthquake that occurred south of Lima on August 15 2007, earthquake lights could be seen across the Lima sky before and during the earthquake. Several videos were taken. ^[3] The 2007 Peru earthquake was an earthquake measuring 8. ...

On May 12, 2008, 30 minutes prior to the Sichuan Earthquake, a cell phone captured footage of multi-colored clouds in the sky (see external link below). The footage was uploaded to Youtube^[4]. However, the footage appears to show a circumhorizontal arc, which is caused by refraction of the sun's light through ice particles in a cirrus cloud, and is similar to a rainbow.^{[citation needed]} Circumhorizontal Arc photographed in Coeur dAlene, Idaho on June 3, 2006 A circumhorizontal arc, also known as a fire rainbow, is an optical phenomenon similar in appearance to a rainbow, caused by the refraction of light through the ice crystals in cirrus clouds. ... For other uses, see Rainbow (disambiguation). ...

Here is a video example. [1]

Theories

The precise mechanism, if such a phenomenon exists—as opposed to being coincidence with aurora or mistaken recall after a traumatic event such as an earthquake—is unknown. One theory suggests that earthquake lights are a form of plasma discharge caused by the release of gases from within the Earth and are electrically charged in the air. For other uses, see Plasma. ...

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.^{[citation needed]} Relationship of the atmosphere and ionosphere The ionosphere is the uppermost part of the atmosphere, distinguished because it is ionized by solar radiation. ... Look up Aurora, aurora in Wiktionary, the free dictionary. ...

Another explanation involves intense electric fields created piezoelectrically by tectonic movements of rocks containing quartz^[5]. Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential[1] in response to applied mechanical stress. ... For other uses, see Quartz (disambiguation). ...

Some similar clouds have been reported during nuclear tests ^[6] and Radon is likely to be an earthquake precursor ^[7], so another theory is that glowing clouds might be light emission produced by Nuclear reactions or ionization and plasma-chemical reactions ^[8] For other uses, see Radon (disambiguation). ... This page is a list of sources of light. ... In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide to produce products different from the initial particles. ... Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. ...

See also

• Earthquake cloud

Earthquake clouds are clouds claimed to be signs of imminent earthquakes. ...

References

External links

• USGS FAQ discussion on Earthquake Lights
• Earthquake lights photos
• Youtube Video: Peru Earthquake 15/08/2007, Lights in the sky at 00:33 and 00:39
• Youtube Video: Peru Earthquake 15/08/2007, Lights in the sky at 00:47 and 00:50
• Youtube Video: Peru Earthquake 15/08/2007, Lights in the sky FULL
• Youtube Video: Peru Earthquake 15/08/2007, Lights in the sky
• Youtube Video: Earthquake clouds recorded 30 minutes before Sichuan Earthquake