Earthquake lights are lights in the sky that are associated with a severe earthquake. Global earthquake epicenters, 1963–1998 An earthquake is a sudden and sometimes catastrophic movement of a part of the Earths surface. ...

History

Records of earthquakes that were accompanied by sky lights can be found in 373 BC in ancient Greek writings, that "immense columns of flame" foretold the earthquake that destroyed the cities of Helike and Bura. 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 (huh-LEE-kee) was an ancient Greek city that sank c. ... This article is about the bora wind. ...

However, even in the early 20th century they were still considered a myth, until photographs of actual lights were taken in Japan in the 1960s. (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... It has been suggested that this article or section be merged with Mythology. ... 1960 (MCMLX) was a leap year starting on Friday (link will take you to calendar). ...

Appearance

The lights are most evident in the middle of the quake, although there are reports of lights that occurred after or even before the earthquake. They usually have shapes similar to those of the auroras and are white to bluish in hue, but occasionally they have been reported to have a wider color spectrum. The luminosity is typically visible for several seconds, but there have been cases in which they lasted tens of minutes. Aurora Borealis Aurora Borealis For other meanings, see Aurora. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ...

There have been also cases in which electromagnetic waves caused by the earthquake interfered with radio transmissions, such as during the Great Chilean Earthquake of 1960. 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. ... The Great Chilean Earthquake of May 22, 1960 is the largest magnitude earthquake recorded since seismographic monitoring began. ... 1960 (MCMLX) was a leap year starting on Friday (link will take you to calendar). ...

Causes

The cause of this phenomenon is unknown, but several explanations have been suggested: A phenomenon(fin-nom-in-on) (plural: phenomena) is an observable event, especially something special (literally something that can be seen from the Greek word phainomenon = observable). ...

• Sparks or gas ionisation due to a piezoelectric effect in quartz-bearing rock
• Frictional heating
• Exoelectron emissions
• Sonoluminescence
• Triboluminescence
• Generation and ignition of flammable gases either from pockets of natural gas or from rocks under enormous stress.
• Gas ionisation or electrical effects due to electrokinetics
• Separation of positive hole charge carriers that turn rocks momentarily into p-type semiconductors

Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ... Quartz is the most abundant mineral in the Earths continental crust. ... Exoelectron emission (EE) is a weak electron emission, appearing only from pretreated (irradiated, deformed etc) objects. ... Image of multi-bubble sonoluminescence created by a high intensity ultrasonic horn immersed in a beaker of liquid. ... Triboluminescence is an optical phenomenon in which light is generated via the breaking of asymmetrical bonds in a crystal when that material is scratched, crushed, or rubbed. ... Natural gas (commonly refered to as gas in many countries, but note that gas is also an American and Canadian shortening of gasoline) is a gaseous fossil fuel consisting primarily of methane. ... Electrokinetics is the science of electrical charges in moving substances, such as water. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ...

External links

• USGS FAQ discussion on EQL
• Earthquake lights photos