A total of 117 earthquakes with magnitudes ranging from 1.1 to 3.2 were recorded in the last 24 hours off the coast of Adalar in the Marmara Sea. According to the data, there has been intense earthquake activity in the Marmara Sea off the Istanbul Islands in the last 24 hours.
KANDİLLİ ANNOUNCED THE LATEST DATA
Kandilli Observatory and Earthquake Research Institute (KRDAE) shared the latest data regarding the earthquakes that occurred in the south of Istanbul Islands on its social media account. Accordingly, a total of 117 earthquakes with magnitudes ranging from 0.7 to 3.1 have been recorded in the region so far. Kandilli's statement is as follows:
"Between 06:00 on 18 August 2026 and 13:00 on 20 August 2026, a total of 117 earthquakes with magnitudes ranging from 0.7 to 3.1 were analyzed in an area with a radius of approximately 20 km in the south of Istanbul, Adalar.
The earthquakes that occurred on 19 and 20 August, for which moment tensor solutions can be made, have a normal component oblique strike-slip focal mechanism. The fact that the source mechanisms are quite compatible with each other shows that the events developed within a similar faulting geometry.
The current activity is a series of microearthquakes clustered temporally and spatially. Such small earthquake clusters can be observed from time to time in active tectonic regions.
Seismic activity in the region; "Earthquakes are monitored 24/7 and evaluated in detail by the KRDAE Regional Earthquake-Tsunami Monitoring and Evaluation Center (BDTIM) in terms of location, depth, size and source mechanism characteristics."
THE BIGGEST IS 3.2
According to records covering 19-20 August, a total of 32 earthquakes occurred in the region. The biggest tremors were recorded at 17.43 on August 19, at a distance of 10.23 kilometers from the Islands, at a depth of 7 kilometers and with a magnitude of 3.2.
SHAKES CONTINUED AT NIGHT
According to AFAD data, earthquakes focused on the Islands increased since the evening hours of August 19. Among the 11 earthquakes recorded on the same day, in addition to the 3.2 earthquake at 17.43, the earthquakes of 2.6 magnitude at 19.17, 2.5 at 20.58 and 1.9 at 22.51 stood out.
Earthquake activity continued repeatedly until the morning hours of August 20. 21 more separate tremors were recorded between midnight and 08.18 in the morning.
During the night, 2.6 magnitude earthquakes occurred at 00.41, and 2.5 magnitude earthquakes occurred at 02.49, 03.33 and 03.45. In the early hours of the morning, two more tremors with a magnitude of 2.8 at 04.31 and a magnitude of 2.9 at 05.40 were recorded.
Micro earthquakes with magnitudes ranging from 1.1 to 2.5 continued to be detected until the last records of the day. It was reported that the focal depths of the earthquakes generally varied between 7 and 17 kilometers.
HAIRLESS: WE WILL WAIT AND SEE
Geological Engineer Prof. Dr. Okan Tüysüz made a statement on his social media account regarding the successive microearthquakes.
Drawing attention to the microearthquakes occurring in the Adalar Fault, Tüysüz stated that these tremors alone cannot be considered as a harbinger of a major earthquake.
Tüysüz said, "It is understood that an earthquake or earthquakes are a precursor when a big earthquake follows it. Microearthquakes on the Adalar Fault have no meaning other than indicating that this fault is active. We will wait and see."
"NOT A QUESTION"
On the other hand, according to the news in AA, Tüysüz said about the earthquakes in question, "There is no indication other than that the fault is active. This is an indication that the fault is alive, not dead, and has the potential to produce an earthquake. It cannot be considered as a sign of any major earthquake." he said.
Stating that the earthquakes need to be monitored a little more in order to be called "earthquake storms", Tüysüz said, "These do not mean that the fault discharges energy because the earthquakes are very small. They only show that stress has accumulated on that fault and the fault has broken little by little, but it does not give a sign that a big earthquake will occur." he said.
BEKTAŞ: NO PANIC
Karadeniz Technical University (KTU) Geological Engineering Department faculty member Prof. Dr. Osman Bektaş made repeated statements on his social media account regarding the increasing microearthquake activity around the Adalar Fault in the Sea of Marmara in recent days.
"DOES THE ISLANDS FAULT CRAWLING DEEP?"
Stating that microearthquake activity at a depth of 10-13 kilometers has been noted in the last 1-2 days along the Adalar Fault in the east of the Çınarcık Basin and the Çınarcık Fault in the west, Bektaş said, "Microearthquakes at a depth of 10-13 km may be an important observation supporting the possibility of creep in the deep part of the Adalar Fault."
Bektaş stated that the stress change following the 6.2 magnitude Silivri earthquake that occurred in 2025 may have triggered this activity.
Stating that Istanbul has historically experienced destruction rather than earthquakes greater than magnitude 7, Bektaş said, "In the destruction, ground amplification was not taken into account. The instrumental period earthquakes of 1935, 1963, 2025 were M6+."
Bektaş also said, "It has now been proven that it creeps in many parts of the Main Marmara Fault."
"DOES THE ISLANDS FAULT SPEND ENERGY AT DEEP?"
Stating that the Adalar Fault continues to produce microearthquakes at a depth of 10-13 kilometers, Bektaş said, "There is no need for the public to panic."
Bektaş said, "I think this activity makes us think that the deep creeping fault may be consuming some of the earthquake energy through small fractures."
"Microearthquakes are not always the harbinger of a major earthquake; sometimes they show how the fault discharges energy," said Bektaş, adding, "A deep-crawling fault may be discharging energy."
"WHAT DO MICROEARTHQUAKES MEAN?"
Stating that the microearthquake activity at a depth of 10-13 kilometers around the islands reminds us of the earthquake clusters in Sındırgı, Bektaş stated that the hot and fluid deep structure of the Marmara can reduce friction and facilitate deep creep by increasing the pore pressure in the fault zone.
Bektaş said, "The breaking of small asperities (locked areas of the fault) during the creep may cause some of the earthquake energy to be wasted by microearthquakes."
"ISLANDS EARTHQUAKE CLUSTER CANNOT BE EXPLAINED BY 'GAS EXPLOSION'"
Stating that the earthquake cluster growing in the Islands developed on the Adalar-Çınarcık fault system, at a depth of approximately 10 kilometers, Bektaş reminded that a 6.3 magnitude earthquake occurred on the same system in 1963.
Bektaş said, "Gas/fluid pressure can trigger fault slippage; however, it is not the gas that produces the earthquake, but the slippage on the fault." He stated that the current cluster should be investigated through the current active deformation, locked and creeping sections of the Adalar Fault, rather than being explained by the "gas accumulation explosion".
"M6+ EARTHQUAKE POTENTIAL CANNOT BE IGNORED"
Bektaş stated that in the studies of Armijo et al. in 2005 and in the studies of Carton et al. in 2007, a young fault rupture with a length of 20-30 kilometers was identified in the Adalar Fault Zone by direct observation of the sea floor, and this was associated with the 6.3-6.4 magnitude earthquake that occurred in 1963.
Stating that there is intense microearthquake activity in the same fault zone today, Bektaş said, "This does not mean 'a big earthquake is coming'."
However, Bektaş stated that the earthquake potential of 6 or more magnitudes cannot be ignored on the Adalar Fault, which broke in 1963 and is producing microearthquakes again today. "The real question is: Do these microearthquakes indicate tension accumulation or energy discharge with deep creep?" he said.
DRAW ATTENTION TO KANDİLLİ'S LATEST RECORDS
Referring to the latest records of the Kandilli Observatory, Bektaş stated that intense microearthquake activity around the Adalar Fault at a depth of approximately 10 kilometers attracted attention.
Stating that this situation suggests the possibility of creep (slow creep) and related stress release in the deep parts of the fault, Bektaş stated that in the 2013 study of Bohnhoff et al., 835 microearthquake activities were observed in the region at the same depth between 2006 and 2010.
Bektaş evaluated, "This picture suggests that the Adalar Fault is a heterogeneous system that creeps deep and can produce M6+ earthquakes from time to time, rather than a completely locked monolithic fault."
"THERE IS NOTHING TO FEAR"
Istanbul Arel University Faculty of Engineering, Head of Civil Engineering Department, Prof. Dr. Mehmet Fatih Altan also said that micro earthquakes occur, but they are not large enough to cause a major earthquake.
Stating that it is pleasing that the magnitude is below 3, Altan said, "If it had reached 4-5, we would have to pay a little more attention. Because this North Anatolian Fault Line is the largest and most dangerous fault line that we need to pay attention to and care about. Therefore, we need to follow and take into account all the movements here.
"The mobility here is very important for us, but since it has been less than 3 so far, there is nothing to fear or cause a major earthquake." made his assessment.
Altan stated that the earthquakes that occur cannot be considered as "earthquake storms" because they are tectonic and said, "There is no such thing as a fault discharging energy. These earthquakes are quite normal earthquakes, there is nothing to be afraid of." he said.
