Twin earthquakes that hit Turkey’s south on Feb. 6 causing more than 50,000 deaths were likely the most potent doublet ever to occur on land anywhere in the world, according to new research published by Chinese scientists, The Jerusalem Post reported.
A doublet is when two or more large earthquakes occur nearby a short time apart.
A 7.8-magnitude quake, which struck near the city of Gaziantep as people slept on Feb. 6, was followed by dozens of aftershocks, including a 7.5-magnitude temblor that jolted the region in the middle of search and rescue efforts the same day.
According to the research, the first mainshock happened around 4:18 a.m. local time and had a moment magnitude (Mw) of 7.95. About nine hours later, a second earthquake struck to the north, with an Mw of around 7.86.
Both estimates are higher than other published results including those of the United States Geological Survey.
“This corresponds to one of the largest tremors in more than 2,000 years of Turkish history,” said Xiaodong Song, chair of the SinoProbe Laboratory in the School of Earth and Space Sciences at Peking University, who led the research that was published this week in the journal of Earthquake Science.
A magnitude 7.8 earthquake that hit the eastern province of Erzincan in 1939 had been considered the deadliest temblor in Turkey’s modern history, leading to the death of more than 33,000 people.
Magnitude is a fundamental parameter for measuring the power of earthquakes and is of great interest to scientific research and the general public, Song said. However, there are often discrepancies when it comes to measuring earthquakes.
In the case of the February events, magnitude results have been reported with significant discrepancies. Even the difference in magnitude between the first and second quakes has appeared highly uncertain, ranging between 0.1 and 0.4.
Song’s team aimed to fill that gap using a novel and reliable long-period coda moment magnitude method to measure the size of the two events.
“The method is specially designed for large earthquakes (MW>7.5), and the results are minimally affected by source complexity and propagation effects,” the first author, Peking University Ph.D. student Xinyu Jiang, explained. “With hours of long-period coda data, the method can produce a robust moment magnitude without further corrections.”
Since completing his latest paper, Song said his research group is collaborating with other groups to determine why such powerful earthquakes occurred now and if there could be a way to predict such events in the future.