Kahramanmaraş.. Geological facts explaining the cause of the horrors of the earthquake

The earthquake that hit Kahramanmaraş left a lot of human and material damage, which raised questions about the reasons that made this natural disaster so devastating.

An article published by the “Anatolia” agency by Okan Twisz, a geological engineer, answered the most important questions raised in this context:

What are the characteristics of the Kahramanmaraş earthquake?

• On February 6, at 04:17 Turkish time and then at 13:24, two earthquakes of magnitude 7.7 and 7.6 occurred in the Pazarıcak and Albistan districts of Kahramanmaraş.
• The Bazargık earthquake occurred on a part of the “Narli” fault in the fault zone of eastern Anatolia, and greatly affected the other faults in the region, triggering the Albistan earthquake on the “Gardak” fault, knowing that the distance between the foci of the two faults is about 90 km.
• The impact of large earthquakes and their creation of small earthquakes is a geological phenomenon that has been studied in the San Andreas fault in the United States and the North Anatolian fault in Turkey. The opposite is less common, that is, small earthquakes rarely lead to stimulating large earthquakes.
• The Kulcuk earthquake (northwest Turkey), which occurred on August 17, 1999, triggered the Duzce earthquake on November 12, 1999 (northwest), that is, after about three months.
• On the other hand, it is known that the earthquake that struck Erzinjan, Turkey, on December 26, 1939, with a magnitude of 7.9, caused four earthquakes, namely: Niksar (in the state of Tuqat – in the northeast) on December 20, 1942, with a magnitude of 7.1, and caused the Tusiya earthquake (Kastamuni state – north) on November 26, 1943, with a magnitude of 7.6.

How was the impact of the second earthquake on the areas covered by the first earthquake?

• Although more than a week has passed since the earthquake, the damage it left behind is still not precisely defined, because it hit a very wide area during the snow season.
• Both the preliminary data and the aftershock distribution show that the area affected by the earthquake is 350 km on the East Anatolian fault line and 150 km on the Gardak fault.
• Preliminary studies indicate that the fault lines that originated in the seismic fault as a result of the 7.7-magnitude earthquake started from the Bazarjik-Narli region towards Celik Khan and then towards the Turkoglu and Gurghan regions.
• During the past days, areas that witnessed shifts in the layers of the earth by about 3 meters were identified, using satellite images, as a fault section of 250 km was identified on the main branch of the eastern Anatolian fault line extending from Qarq Khan to Arkank.
• As a result of the examination of the earthquake waves, cracks were detected in the parts of the main fault, which requires detailed studies.
• The East Anatolian fault is characterized by moving to the left, while there are other faults that slide towards the right side, and are known as faults with right side sliding.
• The two earthquakes in Kahramanmaraş caused surface cracks, some of which were more than 3 meters wide.
• However, given the magnitude of the earthquake, it is expected that there will be other faults more than 6 meters wide. In the 1999 earthquakes, with magnitudes of 7.4 and 7.2, shifts of about 5 meters wide were measured on the right lateral North Anatolian fault line.
• It is very difficult to answer the question of what awaits us after the earthquakes of February 6, 2023, because we do not know exactly what kind of changes the earthquakes brought about in nature.
• However, studies show that new earthquakes can be expected due to the transfer of pressure to the ends of the faults that were shattered in the two earthquakes, and the pressure transfer can push the expected earthquakes forward by accumulating pressures on the faults that are capable of producing earthquakes, which can occur in a short time very or may take years.
• In this sense, and considering the movement directions of the 6 February earthquakes, it is believed that there may be an increase in pressure on the Celikhan-Surko, Gulbaşı-Caglayangret, Antakya-Cyprus, and Koksu-Közan faults.
• However, for these studies to reach satisfactory results, all field studies on fault data must be completed.

Hundreds of thousands of people affected by the earthquake in Turkey are living in tents

How did the Kahramanmaraş earthquake affect the seismic map of Turkey?

• Although the second earthquake occurred about 90 kilometers north of the first quake, it caused a strong tremor in the northern areas affected by the first quake.
• When a comparison of the maps is made, it can be seen that the area where the second earthquake occurred seemed stronger and also includes the places that were damaged by the first.
• This indicates that the residential areas within the covered areas (such as Adıman and Kulbaşı) were severely damaged by the earthquakes. It is also noted that the influence of the second fell to Antioch, the city that suffered the most damage.