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In the 2nd century BC Greek astronomer Erastosthenes accurately measured the distance around the earth at about 40,000 km (24,860 miles) - but nobody believed him. |
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Earthquake Lights
Posted on Wednesday, April 20, 2005 (CDT) by Isis
LuLusDen writes: "
The first recorded sighting of earthquake lights dates back to 373 BC in Greece, but stories have long been told of strange lights in the skies before, during and after an earthquake.
Today their existence is an accepted fact, although the mechanism that generates them is still a mystery. The first known scientific investigation of earthquake lights took place in the 1930s, and in the 1960s earthquake lights were well documented in a series of photographs taken in Japan.
Eyewitness descriptions:
The lights are most evident in the middle of a quake. People who have seen them sometimes describe them as searchlights and sometimes as fireballs or lightning. Other witnesses describe them as consisting of beams and columns of light, and still others report clouds that were illuminated during earthquakes or simply an eerie glow in the sky.
In an article in Nature titled "Earthquake Lights and Seismicity," Marcel Ouellet described the lights that appeared during a three month period from November, 1988 through January, 1989, during a series of seismic shocks that occurred in the Saguenay region of Quebec, Canada:
Fireballs a few metres in diameter often popped out of the ground in a repetitive manner at distances of up to only a few metres away from the observers. Others were seen several hundred metres up in the sky, stationary or moving. Some observers described dripping luminescent droplets, rapidly disappearing a few metres under the stationary fireballs. Only two fire-tongues on the ground were reported, one on snow and the other on a paved parking space without any apparent surface fissure. The colours most often identified were orange, yellow, white and green. Some luminosities lasted up to 12 min.
Flashes of light were widely reported before the 1995 earthquake at Kobe, Japan:
Some residents of Kobe and nearby cities saw aurora-like phenomena in the sky just before and after the quake.
A Kobe firefighter observed a bluish-orange light above a shaking road that lasted about 4 seconds.
A hotel employee on his way to work on Rokko mountain: "saw a flash running from east to west about two to three meters above the ground shortly after the quake. The orange flash was framed in white."
Flashes of light were widely observed.
(Science Frontiers #99, MAY-JUN 1995. © 1997 William R. Corliss)
One of the strongest earthquake illuminations came during Chinese earthquake of 1976, when it was reported that the lights at the centre of the earthquake were bright enough to turn night into day. As far as 320 kilometres from the epicenter of the quake people woke up thinking their room lights had been turned on.
Just last year, on June 4, 1998, residents of the Charlotte, North Carolina area reported seeing a bright flash when the area north of Charlotte was hit by a 3.2 magnitude earthquake. Oddly, the National Earthquake Center denied that the North Carolina flash would have been attributable to the 3.2 quake on June 4. The flash was said to have been so bright that area residents at first thought that a meteor had struck the ground.
What causes earthquake lights?
The most common explanation for earthquake lights is the piezoelectric effect in quartz-bearing rock. Quartz has the unique attribute of emitting electricity under pressure. Laboratory experiments have shown that this effect can produce light emissions, but they are, at least in the laboratory, of much shorter duration than reported earthquake lights.
Some researchers theorize that earthquake lights are produced by seismic stresses that may generate high voltages that create small masses of ionized gas, which are then released into the air near the fault line.
A second popular theory is that, during an earthquake, small pockets of trapped natural gas are released and ignited by friction. These burning balls of gas then rise in the air and create the effect of the lights.
Another theory is that the pressure generated during earthquakes may cause water molecules to separate into atoms of hydrogen and oxygen, then quickly recombine back to water. In the process they theoretically could release light and create the mysterious earthquake lights.
Next week: Are "spook lights" related to earthquake lights? Join me as we investigate some of the better-known "ghost lights" in America.
What do you think causes earthquake lights? Discuss in the forum
Related Articles
Telegeodynamics
Earthquake Lights
Related Websites:
Earthquake Lights Observed in Canada
From Science Frontiers #74, MAR-APR 1991.
The North Carolina Quake
From Science Frontiers #99, MAY-JUN 1995.
Thomas Gold 1987
Eye-witness accounts of several major earthquakes and the strange phenomena that occurred during them.
Source
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