Decode earthquake light phenomenon

For centuries, scientists have recorded numerous reports of strange light phenomena that appeared before or during earthquakes. They call it earthquake light.

Mysterious light phenomenon

Recent discoveries suggest that earthquakes seem to occur at the cracks of the Earth's crust , where Earth's tectonic plates are separate from each other. Earthquake light can last a few seconds or even minutes depending on the situation.

' Earthquake light has many different shapes and colors . Common forms of earthquake light include blue flames emanating from the ground and stopping at the height of the ankle, spheres of light suspended in the air, or lightning-like flashes Ordinary lightning, except that they appear from the ground instead of from the sky and can launch up to 200m ' , Friedemann Freund, a physicist at San Jose State University (USA), and a researcher Advanced research at the Ames Research Center of the US Aerospace Agency (NASA), said.

Previously, scientists suspected whether earthquake light really existed. But since the 1960s, countless photos and videos have proved this natural phenomenon to be real.

The most famous photo of earthquake lighting was taken at Mount Kimyo, Japan in 1968. (Photo: Kuribayashi).

When a magnitude 8.1 earthquake struck in Mexico in 2017, images of exotic blue and green light streams in the sky spread widely on social media. Assembly

In 2011, during the historical earthquake in Japan, it was recorded a strange and interesting phenomenon in the sky. A sphere of light-colored, purple-blue color appears in the city of Sendai, the capital of Miyagi Prefecture (one of the provinces that suffered the most damage as a result of the earthquake and tsunami). Light spots appear, bulge out, blink a little before shrinking and disappear. The whole process takes about 7 seconds.

Just a few seconds before the earthquake occurred in L'Aquila, Italy, in 2009, roadgoers saw strips of 'dancing' light at a height of about 10cm, above the boulevard Francesco Crispi. In 2007, many witnesses and security cameras spotted bright lights in the sky during the magnitude 8 earthquake that struck Pisco, Peru.

People have also seen rainbow-like bands of light before the massive earthquake of 1906 in San Francisco. On November 12, 1988, some witnesses reported a purple ball of light - pink moving along the St. River. Lawrence in Quebec (Canada). Exactly 11 days after this phenomenon, a strong earthquake happened here.

Scientific explanation

Scientists have a hard time trying to study the phenomenon of earthquake light because it rarely happens, and often only appear in a short time.

In an article published in Seismological Research Letters in 2014, Freund and colleagues analyzed 65 reports of earthquake lighting in the US and Europe from the 1600s. Results showed that about 85% of cases of earthquake light appear directly above or near geological faults, where seismic activity occurs.

The team proposed the theory that earthquake light was formed by the discharge properties of some rocks when subjected to high pressure between tectonic plates, such as basalt and gabbro. In some areas, basalt and gabbro rocks are present in the vertical structure of the Earth's crust, to a depth of about 97km. They have small defects in the lattice so it is easy to release the charge. The charge can combine and create a kind of plasma-like state, which can move at very high speeds, explode on the ground and discharge electricity into the air creating a series of colorful flashes.

'When nature puts pressure on some rocks, the charge is activated as if you turned on a battery in the Earth's crust , ' Freund said.

Some other theories are also used to explain earthquakes, including the breakdown of the Earth's magnetic field due to tectonic stress and the so-called piezoelectric effect , in that rock bearing quartz minerals creates a strong electric field when compressed in a certain way.

Scientists estimate that the conditions for creating earthquake light exist only in less than 0.5% of earthquakes worldwide. This phenomenon appears most popular in Italy, Greece, France, Germany, China and part of South America, although they are also observed in Japan, North America and some other places.

Earthquake forecast

Freund is collaborating with many scientists to build a global earthquake prediction system. Freund believes that the phenomenon of earthquake light will be a sign that seismic activity may happen in the future.'Although this phenomenon is relatively rare. But if it appears, let us be careful , ' Freund said.

Contrary to Freund's view, Bruce Presgrave - a geophysicist at the National Geological Survey's US Earthquake Information Center - says the phenomenon of earthquake light does not seem very useful for forecasting. earthquake, because it is not reported regularly.

In the past, however, some people survived by knowing this phenomenon. Just before the earthquake took place in L'Aquila (Italy) in 2009, a man saw bright flashes in the kitchen. Because he had read information about earthquakes, he moved his family to a safer place. In 1976, a Chinese geologist sought refuge after seeing the earthquake light, shortly thereafter the Tangshan earthquake took away the lives of hundreds of thousands of people.

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