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Unusually high land temperatures and levels of greenhouse gases in the air were observed in Turkey days before two earthquakes struck the country on February 6, 2023, a new research has found.
Analysing satellite data from November 1, 2022 to February 10, 2023, Mehdi Akhoondzadeh from the University of Tehran, Iran, said that monitoring the ground and atmosphere for unusual physical and chemical parameters -- known as earthquake precursors -- could be part of an early warning system for earthquakes.
The earthquakes that hit Turkey and Syria were each of at least 7.6 magnitude and about nine hours apart. The death toll is said to be more than 50,000 and the earthquakes were the deadliest ones in modern history.
Even though researchers are aware of earthquake precursors, it has so far been difficult to conclusively identify a pattern of such "red flags" that could foretell an impending earthquake, said the author of the study published in the Journal of Applied Geodesy.
This is because the interactions between these entities is complex and so is their variability across different earthquakes and geographies, said Akhoondzadeh.
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However, with every earthquake that researchers analyse using satellite observations, patterns between these earthquake precursors are slowly emerging, according to Akhoondzadeh.
In the study, the author observed abnormal temperatures on land surface as early as 12-19 days preceding the earthquakes.
Akhoondzadeh also found unusual levels of water vapour, methane, ozone and carbon monoxide in the air 5-10 days before the seismic shocks. Levels of charged particles such as electrons were found to be unusually high 1-5 days preceding the quakes (in the ionosphere).
While various processes have been proposed to explain the unusual occurrences across layers of the Earth before an earthquake, none of them have been conclusively proven, the author said in the study.
Some of these include "warm gases radiated due to melt fluids formed inside the earth before the earthquake" and "the activation of positive (charges) due to the pressure of underground rocks and their reaching the surface of the earth," the author wrote.
Studying these phenomena could pave the way for earthquake early warning systems, but researchers will need to assess other earthquakes in the future to more fully understand these patterns, said Akhoondzadeh.
Data from the Chinese seismo-electromagnetic satellite, CSES-01, and the Swarm mission, consisting of three satellites from the European Space Agency, were used in the analysis.
