Over the centuries, scientists have recorded many reports of strange lights appearing before or during earthquakes. They call it earthquake light.
Recent discoveries show that earthquake flares seem to occur at faults in the Earth’s crust , where the Earth’s tectonic plates are separating from each other. Earthquake lighting can last a few seconds or even minutes depending on the case.
“ Earthquake light comes in many different shapes and colors . Common forms of earthquake light include blue flames that shoot up from the ground and stop at ankle height, orbs of light suspended in the air, or flash-like flashes of light. ordinary lightning, the only difference is that they appear from the ground instead of the sky and can be launched to a height of 200m,” said Friedemann Freund, a physicist at San Jose State University (USA), and a researcher Senior Research Fellow at NASA’s Ames Research Center.
Previously, scientists doubted whether earthquake light really existed. But since the 1960s, countless photos and videos have proven this natural phenomenon to be real.
The most famous photo of earthquake light was taken at Mount Kimyo, Japan in 1968. (Photo: Kuribayashi).
When an 8.1-magnitude earthquake struck Mexico in 2017, images of strange green and blue lights in the sky went viral on social media. festival.
In 2011, during the historic earthquake in Japan, a strange and interesting phenomenon was recorded in the sky. A spherical, purple-blue light appeared in Sendai City, the capital of Miyagi Prefecture (one of the prefectures that suffered the most as a result of the earthquake and tsunami disaster). The spot appears, expands, blinks a little before shrinking and disappearing. The whole process takes about 7 seconds.
Just seconds before the earthquake that struck L’Aquila, Italy, in 2009, passersby saw bands of light “dancing” about 10cm high, above Francesco Crispi Avenue. In 2007, many witnesses and security cameras detected bright flashes of light in the sky during the magnitude 8 earthquake that struck Pisco, Peru.
People also witnessed bands of light like a rainbow before the great earthquake in 1906 in San Francisco (USA). On November 12, 1988, several witnesses reported a purple-pink ball of light moving along the St. Lawrence in Quebec (Canada). Exactly 11 days after this phenomenon, a strong earthquake occurred here.
Scientists find it difficult to study the phenomenon of earthquake light because it occurs rarely, and often appears for a short time.
In a paper published in the journal Seismological Research Letters in 2014, Freund and colleagues analyzed 65 reports of earthquake light in the United States and Europe from the 1600s. The results showed that approx. 85% of earthquake flares occur directly above or near geological faults where seismic activity occurs.
The team hypothesizes that earthquake lighting is caused by the electrical discharge of certain rocks when subjected to high pressure between tectonic plates, such as basalt and gabbro. In some areas, basalt and gabbro are present in the vertical structure of the Earth’s crust, up to a depth of about 97 km. They have small defects in the lattice that make them easy to release charges. Charges can combine and create a kind of plasma-like state that can travel at very high speeds, explode above the ground, and discharge electricity into the air creating a series of colorful flashes.
“When nature puts pressure on certain rocks, the charge is activated as if you were turning on a battery pack in the Earth’s crust,” Freund said.
Several other hypotheses have also been used to explain earthquake light, including disruption of the Earth’s magnetic field due to tectonic stress and the so-called piezoelectric effect , in rock that carries the mineral quartz produces a strong electric field when compressed in a certain way.
Scientists estimate that the conditions to produce earthquake light exist in less than 0.5% of earthquakes worldwide. This phenomenon occurs most commonly in Italy, Greece, France, Germany, China and parts of South America, although they are also observed in Japan, North America and elsewhere.
Freund is collaborating with many scientists to build a global earthquake prediction system. Freund believes the earthquake light will be an indication of possible seismic activity in the future. “Although this phenomenon is relatively rare. But if it shows up, let’s watch out,” Freund said.
Contrary to Freund’s view, Bruce Presgrave, a geophysicist at the US Geological Survey’s National Center for Earthquake Information, said that earthquake light does not appear to be very useful for forecasting. earthquake, because it is not reported often.
However, in the past, some people have survived because of their knowledge of this phenomenon. Just before the earthquake that struck L’Aquila (Italy) in 2009, a man saw bright flashes of light right in the kitchen. Because he had read about earthquake light, he moved his family to a safer place. In 1976, a Chinese geologist sought shelter after seeing the light of an earthquake, which was immediately followed by the Tangshan earthquake that claimed the lives of hundreds of thousands of people.