Over many years, scientists have observed a unique phenomenon in which lightning is associated with earthquakes, both before or during an earthquake, and this phenomenon has been called “earthquake lightning.”
This phenomenon was observed repeatedly in Japan, where the successive series of earthquakes in the Matsushiro earthquake were accompanied by lightning and flashes in the surrounding mountains, on many periods between 1965 and 1967.
In 1993, an earthquake in southwest Hokkaido caused a tsunami off the coast, causing 5 boats to ignite and burned ashore.
As usual, opinions differed in explaining this phenomenon. Some attributed it to an electrical short circuit in the electrical power supply wires in the affected area, and some attributed it to problems in the electric power plants themselves during the earthquake.
However, Professor Emeritus Yuji Inomoto from Shinshu University believes – according to the press release published on the Eurek Alert website on September 28 – that it is not possible to interpret such a complex phenomenon in a unified manner according to a unified natural model, that Certainly, there are many factors that contribute to its occurrence.
Rock quality and lightning
In their study, published in the journal Earth, Planet and Space, Inomoto and his team reviewed the study of the effect of rock sliding on the phenomenon of “earthquake lightning”.
In the study, the researchers used high-speed, high-resolution, ultra-sensitive cameras, and spectrometers to analyze the highly sensitive light spectrum.
The team studied the reports of seismic lightning in the Japanese archives since 869 AD, and found that at least 9% of the documented reports were due to landslides, as light is emitted when rocks that slide from their place collide during an earthquake.
The team selected different types of rocks that make up the mountains and plains of Japan, such as granites, lava rocks, rhyolite, limestone and serpentine.
They found that the mechanism of lightning occurrence differs according to the type of rocks in the area that is within the range of the earthquake’s impact, and that some rocks – such as serpentinite – do not emit light at all.
There are many cases in which rare cases of electromagnetic anomalies associated with earthquakes have been documented.
For example, the number of electrons in the ionosphere suddenly increased above the epicenter about 10 minutes after the 2011 Tohoku-Aoki earthquake, which measured 9.0 on the Richter scale.
By studying this event, the team proposed a model of coupling of the lithosphere, water, atmosphere and ionosphere in a range of charged fog that could be the cause of the emergence of lightning.
The team is currently working to clarify the reasons behind the lightning observed during the 1995 Hyogo Kin Nanpo earthquake, as the sky became brighter, and then the color changed from bluish purple to white and then red.
The team led by Professor Inomoto hopes that understanding such phenomena will advance earthquake prediction and enhance effective disaster prevention.