The small earthquakes that occurred one after the other in the Marmara Sea in the last 24 hours have brought the seismic activity in the region back to the agenda. According to the statement made by Kandilli Observatory on its official
After the earthquakes, attention was once again turned to the active faults of Marmara, and remarkable evaluations came from experts. Prof. Dr. Süleyman Pampal objected to the "dead fault" interpretations, especially for the Adalar Fault, and drew attention to the earthquakes it had produced in the past.
Prof. Dr. Süleyman Pampal made evaluations about the earthquake activity around Istanbul and the Marmara Sea. Pointing out that the Adalar Fault has produced major earthquakes in the past, Pampal stated that it is not correct to describe the fault as "dead" and underlined important information:
"We know that the Adalar Fault broke in 1894, produced an earthquake of approximately 7 magnitude, and then produced another earthquake of magnitude 6.3 in 1965. This is in the records. Therefore, the fact that this fault has produced earthquakes in the past shows that it should be considered an active fault today. We see that some experts describe this fault as a 'dead fault', but I do not agree with this opinion. The Adalar Fault continues to be active. However, this fault does not affect Istanbul or Istanbul." "I do not think it will produce a very large earthquake that will completely destroy the Marmara Region, but since it is a fault that has produced large earthquakes in the past, it should not be ignored that it has the potential to produce an earthquake."
Emphasizing that the evaluation of faults as active or passive is closely related to the tectonic regime in the region, Prof. Dr. Süleyman Pampal pointed out that the existing deformations in Marmara continue:
"The evaluation of a fault as dead or alive is closely related to whether the tectonic regime of the region it is in has changed. There is no fundamental change in the neotectonic regime in the Marmara Region. The same tectonic regime continues, the same macro deformations continue. Right-lateral slip-slip movement continues in the region and there is a general deformation of approximately 2 to 2.5 centimeters per year. Therefore, it can be said that the faults, which are parts of these major tectonic movements, have completely lost their activity." "It is not possible. The Adalar Fault is one of the faults that continues to be active in this system."
Prof. stated that it is not correct to describe small earthquakes as "foreshock earthquakes". Dr. Süleyman Pampal said that the foreshock can only be identified retrospectively after a larger main shock occurs.
Pampal said, "Foreshock earthquake is a phenomenon that we rarely encounter. We can say that an earthquake is a precursor only when a larger main shock follows it. In other words, it is not scientifically possible to look at an earthquake that occurred today and say 'this is a foreshock'. When we look back after the main shock occurs, we understand that some of the smaller earthquakes that occurred before were precursors. We encounter such earthquake series from time to time in Turkey. Similar examples have occurred before in Balıkesir Sındırgı, Denizli and other regions. However, now "We do not consider these earthquakes that occurred in Marmara as a foreshock series based on the data we have. These are not earthquakes that can be interpreted as such at this stage," he said.
"Looking at the earthquakes that occur here, we should not think that a large part of the main fault has broken," said Prof. Dr. Süleyman Pampal said, "The ruptured area in such micro-earthquakes may be limited to a few kilometers or even shorter. Because what we call micro-earthquakes are small earthquakes that occur when micro-scale fault parts break. These do not mean that the entire or a large segment of the main fault has broken."
Stating that the earthquakes in question did not occur on the main segment of the Middle Marmara Fault, Pampal drew attention to the secondary faults and said, "The earthquakes here are not ruptures on the main direction of the Middle Marmara Fault. In the regions between the segments, there are smaller secondary faults that cut the main Marmara Fault at certain angles and extend in different directions. We evaluate that the currently observed small earthquakes largely occur on these secondary faults in different directions, which have the potential to produce small earthquakes. Therefore, it would not be correct to interpret this activity as the rupture of a large part of the main Marmara Fault."
Prof. also drew attention to the large earthquakes produced by the faults in the Marmara region in the past. Dr. Süleyman Pampal stated that after the 1999 earthquakes, the rupture process in the region continued towards the east.
Pampal said, "Inside the Marmara, the eastern part of the northern branch of the North Anatolian Fault broke in the earthquake of August 17, 1999. A significant part of the energy released during this earthquake was later gradually released by aftershocks. I had calculated how much energy the aftershocks released in those years. However, I did not expect the rupture to continue in the same way towards the west or into the Marmara. In fact, the rupture moved towards the east and on November 12. "We experienced another earthquake in 1999," he said.
Stating that historical earthquakes in Marmara are also of great importance, Pampal drew attention especially to the 1766 and 1894 earthquakes: We know that the Adalar Fault broke in 1894. The northern branch of the Marmara had been seriously broken before, especially with the great earthquake that occurred in 1766, and it had a very heavy impact on Istanbul. A significant part of the historical major damages in Istanbul is related to this 1766 earthquake.
