The first earthquake in Turkey could give the final impetus to the second

The first of two powerful earthquakes it shocked Türkiye And Syria On February 6, he was able to give the “final push” to the second, turning this event into a double earthquakes.

The researcher explained in a statement to ETH Zurich Luca Dal Zilio, co-author of the study, that their centroids, with a difference of nine hours and the same magnitude, are closer than the size of their gap and occur within a time frame that is shorter than the repetition time inferred from plate movement. the author of the commentary on these recent earthquakes in Communications Land and environment.

it was not a replica

Second earthquake in this case it was not a typical aftershock as it was almost as strong as the first one and occurred along another nearby fault. According to Bath’s law, the strongest aftershock is usually about 1.2 magnitudes smaller than the first. earthquake main.

According to Dahl Zilio, the first earthquake probably contributed to the increase in static voltage in the area where the second event occurred. “While this increase may have been small, it could have been enough to trigger a second event just a few hours later. This suggests that both faults were under critical stress,” he explained.

Thus, he believes that the first earthquake it could give the final impetus to the second fault zone, which has accumulated stress over decades and is already critically loaded.

Significant damage can not be avoided earthquakes of this magnitude, especially when cities are located exactly on seismically active fault lines, which cause large surface displacements of six to eight meters.

Culture of Prevention

According to this expert, this event highlights the need to better understand the strong ground movement near the fault and update risk management practices, such as calculating how stress transfer has changed the likelihood of a hazard in the region. . Ideally, we should also find out to what extent strong mainshocks have changed the stability of buildings and made them more vulnerable to aftershocks.

On the other hand, Dal Zilio noted that the North Anatolian Fault and the East Anatolian Fault, which cross Türkiyeare the two most active fault systems in Europe and the world and therefore pose a significant seismic hazard to the region.

The North Anatolian Fault, on which Istanbul lies, also poses a significant risk. There were several earthquakes along this fault in the last century. These events have now left a seismic gap south of Istanbul and below the Sea of ​​Marmara, a gap that has not been filled for 250 years. Seismologists often refer to these regions as seismic breccias because they are sections of a fault system where there has been little or no seismic activity for a long period of time, even if neighboring sections have been hit by earthquakes. earthquakes.

“We hypothesize that these are areas along the fault where stress builds up before a huge amount of energy is released, which can lead to large earthquakes,” he said. (Europe Press)

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