Study traces Turkey quake to interrupted ‘chat’ between fault lines

Subject: Geography

Section: Physical geography

Context:

A pair of powerful earthquakes struck Turkey and Syria in February 2023. The earthquakes weren’t entirely unexpected given Turkey’s seismic history, but scientists were startled by their unprecedented scale. A study unearthed the intricate union of tectonic forces that led to the disaster.

Geological anatomy:

The earth’s crust consists of tectonic plates. Fault lines form where these plates interact, as they collide,pull apart or slide past each other. When these plates abruptly grind and slip past each other, they release pent-up pressure, leading to earthquakes.
The earthquakes in Turkey occurred along the East and North Anatolian Fault Lines, which run 700 km and 1,500 km long, respectively.
A seismic “cascade” broke through fault bends and step-overs, which are otherwise barriers to the propagation of an earthquake.

Cascade of ruptures:

The unusual interaction initiated a cascade of ruptures, resulting in a larger-than-usual total rupture length and a more tremendous potential for destruction. In places where there were no buildings and/or where no people died, scientists observed craters after the earthquakes.
- The first earthquake (M7.8) struck near Gaziantep on a strike-slip fault, a type of tectonic plate boundary where two plates slide horizontally past each other.
- The next quake (M7.7) hit near Ekinözü, roughly 200 km north. They caused substantial damage along the East Anatolian Fault, which runs through eastern Turkey, extending from near Turkey’s border with Syria to the northeastern region.
The Narlı Fault and Çardak–Sürgü Fault Zone are also primarily located in eastern Turkey. They extend from the southern part of Turkey to the northeastern part, roughly parallel to the border with Armenia.
- They both experienced separate earthquakes. The ground near the coast some 200 km to the southwest began to move like a liquid. The Cyprian geological survey department recorded a minor tsunami near the island in the eastern Mediterranean Sea.

Comparative analysis:

The above study was distinguished by two methods: kinematic slip inversion and fault-property modelling.
- Kinematic slip inversion is like rewinding an earthquake video to understand how fault surfaces moved, indicating what might have occurred underground.
- In fault-property modelling, researchers estimate the characteristics of the fault, like friction and material properties, to predict how an earthquake is likely to spread along it.
These predictions are then compared to real earthquake data to gain insights.

Source: TH