Earthquake Lights: Bizarre Atmospheric Phenomena
Imagine observing strange glowing balls hovering over the dark evening sky seconds before an earthquake strikes. These bizarre and enigmatic events—earthquake lights—have baffled scientists and amazed witnesses for millennia. The event is still not well understood, but current research suggests the lights could be linked to the piezoelectric effect of pressurized rocks, among other possibilities.
What Are Earthquake Lights?
Earthquake lights (EQL) are light events that, sometimes, take place in the air ahead of, simultaneous with, or following seismic activity. The lights have been described as glowing globes, flashes, or streaks immediately over tectonically stressed locations. The lights are brilliant white, to blue, and at times reddish, and tend to be ephemeral, lasting no more than a few seconds or minutes. Notwithstanding numerous hundreds of eyewitness reports over a number of centuries, earthquake lights remain one of nature's biggest mysteries.
On the Wikipedia article for Earthquake Light, it has been observed all over the world and while not every earthquake is accompanied by such occurrences, sporadic observations have led scientists to examine various hypotheses.
Historical and Contemporary Observations
There are countless historical accounts across cultures detailing the phenomenon of bizarre lights during earthquakes. There are accounts of otherworldly glows in the sky prior to devastating earthquakes from ancient Mediterranean lore and legend, East Asian history, and the Americas. There are eyewitness accounts of such occurrences up to the present day. For instance, in the California 1989 Loma Prieta earthquake, there were several eyewitnesses who described observing strange flashes and glows in the sky. More recently, advances in camera technology and video recording have picked up fleeting pictures of these lights, which have again excited scientific interest.
The unpredictable nature of earthquake lights makes them difficult to research in a systematic way. But as technology has improved and more data are obtained, scientists arebeginning to assemble pieces of a puzzle that may explain when and how they occur.
The Science Behind the Phenomenon
Piezoelectric Effect in Rocks
The piezoelectric effect is the most popularly accepted theory of earthquake lights. Certain crystalline rocks, such as quartz, develop an electric charge when subjected to mechanical stress. During a coming earthquake, the immense pressure developed in the Earth's crust might make the piezoelectric materials release electrical energy. The energy would ionize the air around it even more, giving rise to light.
Though this is a likely description, it is not typical. Even the piezoelectric effect itself might be too simple to account for all the said characteristics of earthquake lights, such as their altered colours and whimsical motions. However, it provides a scientific paradigm relating geological stress to aerial luminosity.
Alternative Hypotheses
There have also been other proposals trying to account for earthquake lights. Some other scientists indicate that frictional heating on fault lines might create electrical discharges, as sparks are created when two surfaces are rubbed together. Yet another theory proposes that the rapid motion of the tectonic plates might create an electrical current in the Earth's crust, causing it to glow. A second theory is that the rupture and reformation of chemical bonds in stressed rocks might release energy as visible light.
Despite these many hypotheses, none have been widely accepted yet. The variety of observations reported suggests that multiple mechanisms are likely at work, depending on the prevailing geological and atmospheric conditions during the earthquake.
Observational Challenges and Research Approaches
Observation of earthquake lights will also be difficult since they are uncontrolled and ephemeral. Unlike other natural phenomena that can be observed under controlled conditions, earthquake lights are formed spontaneously during an earthquake, and these are difficult to predict reliably. Scientists are therefore forced to rely heavily on witness testimony, video recordings, and,