Distributed Acoustic Sensing (DAS) applied to existing fiber optic telecommunication cables provide dense spatial measurements and enables seismic monitoring in regions where conventional instrumentation is limited. In this study, we evaluate the performance of a submarine DAS system deployed along a ~60 km fiber-optic telecommunication cable for earthquake detection and monitoring in the Marmara Sea, Türkiye.The DAS interrogator, installed at Tavşantepe Metro Station in İstanbul, continuously records strain-rate data with 10 m channel spacing and a sampling rate of 1500 Hz. The cable extends between the Istanbul mainland and the Princes’ Islands, crossing the Marmara Sea in close proximity to the North Anatolian Fault, thereby enabling continuous offshore seismic observations in one of the most seismically critical regions of Türkiye.Since early 2023, the system has recorded more than 1,500 seismic events with magnitudes ranging from Mw 1.7 to 7.8, as well as teleseismic events up to Mw 8.8. In addition to cataloged earthquakes, the DAS data reveal smaller local events that are not clearly detected by traditional seismic networks. This highlights the high sensitivity of the system, enabled by its dense spatial sampling.We implement a simple real-time detection approach based on characteristic functions applied to selected DAS channels, showing that earthquake signals can be detected reliably under operational conditions. The continuous spatial sampling along the cable also allows following the wavefield propagation over tens of kilometers.The dataset also reveals several important limitations of the current system. During the April 23, 2025 Silivri, İstanbul earthquake (Mw 6.2), the DAS recordings exhibit clear signal saturation, indicating that the current interrogator dynamic range is insufficient for strong ground motion. The distance of the nearest channel to the source zone of the Silivri earthquakes was less than 40 km. Magnitude estimates derived from DAS data agree well with national catalogs for moderate events, but show increasing deviations for larger magnitudes (approximately Mw ≥ 5.0), likely due to this saturation effect. In addition, the linear geometry of a single cable limits the accuracy of standalone event location.Overall, the study demonstrates the operational feasibility and long-term stability of submarine DAS systems for real-time earthquake monitoring in the Marmara region, while also highlighting current instrumental and geometrical limitations that must be addressed for future earthquake early warning and rapid response applications.

The Istanbul Natural Gas Distribution Company has started monitoring seismic activity within the Sea of Marmara using a fiber-optic (F/O) cable integrated with a Distributed Acoustic Sensing (DAS) system in order to mitigate secondary disasters that may occur after earthquakes and to protect critical infrastructures, such as pipelines. The monitored F/O cable, originally designed for telecommunications purposes, extends over a length of 60 kilometers beneath the Sea of Marmara. In 2022 October, this cable is integrated with a DAS system through an interrogator unit, installed at Tavşantepe Metro Station. The system consists of an analyzer that allows detection up to 40 kilometers, operates with a spatial channel spacing of 10 meters, in total 3910 channels, and a sampling rate of 200 Hz, enabling high-resolution seismic data acquisition. The cable’s route follows several critical regions: it enters the Sea of Marmara, traverses Büyükada, runs behind the Princes' Islands parallel to the Marmara Fault, intersects the fault at multiple locations, and ultimately terminates on land at Ambarlı. This strategic placement provides extensive coverage for monitoring seismic activity along this geologically active region.Since the beginning of 2023, more than 500 earthquakes, with magnitudes ranging from 0.7 to 7.8, have been recorded using the F/O cable. Our analysis reveals that the quality of recorded seismic signals is strongly influenced by two factors: the incidence angle of wave on the cable and the cable's coupling with the ground. Poor coupling reduces the energy transfer from the ground to the cable, leading to weaker or distorted signals, while unfavorable incidence angles of wave, affect the strain response detected by the DAS system. These findings highlight the importance of optimizing cable placement and ensuring effective coupling for reliable seismic monitoring.The developed algorithms have enabled the real-time automatic detection of earthquakes occurring within and around the Sea of Marmara using the F/O cable, and the initial results have been promising. The first real-time detection is accomplished for the M3.9 Çanakkale earthquake occurred on 19 November 2024 at 07:46:15 UTC. The F/O cable detects the earthquake 33 seconds following its occurrence, and the system sent an automatic detection notification approximately 1 second later after detection.As part of our project, at the beginning of January 2025, a vessel-based survey is conducted to determine the submarine position of the F/O cable passing beneath the Sea of Marmara. This study contributes to improving the application of DAS in submarine seismic observation and highlights potential challenges in data acquisition from F/O cables.

The Istanbul Natural Gas Distribution Company (İGDAŞ) has recently embarked on utilizing existing Fiber-Optic (F/O) cables to enhance disaster prevention and mitigation efforts in Istanbul. We are exploring the potential of a novel technology called F/O Distributed Acoustic Sensing (DAS) for earthquake early warning systems. The strategic placement of the F/O cable, which crosses the North Anatolian Fault in the Marmara Sea, presents a unique opportunity for monitoring seismic activity. While seismic stations exist around the Marmara Sea, the absence of online operating Ocean Bottom Seismometer (OBS) stations makes the F/O cable the only sensor positioned across the fault lines expected to rupture during a major earthquake.The monitored F/O cable, originally intended for telecommunications, spans 60 kilometers in the Sea of Marmara. Over the past 7 months starting in June 2023, more than 160 earthquakes ranging from magnitudes 1.0 to 7.5 have been recorded through the F/O cable. Notably, the F/O DAS system successfully captured significant distant events, notably the February 6, 2023, M7.8 and M7.5 earthquakes in Kahramanmaraş. This initiative highlights the critical stages, obstacles, and best practices associated with deploying this technology. It underscores the importance of precise cable layout, optimal sensor density, range optimization, and the conduction of shaking table tests.Shaking table experiments were conducted to compare noise levels across various sampling rates. By subjecting a Force-Balanced Accelerometer (FBA) and F/O cable to simulated seismic activity resembling the 1999 Sakarya Earthquake (M6.9) with sine signals at frequencies of 0.25 Hz, 0.5 Hz, 1.5 Hz, 2 Hz, and 3 Hz, observations revealed that reducing the sample rate to 200 sps significantly lowered the interrogator's instrumental noise compared to 2000 sps. Hence, a lower sample rate proved advantageous in achieving a better Signal-to-Noise Ratio (SNR).Through the analysis of acoustic signal variations along the F/O cable, the DAS systems can accurately pinpoint and characterize earthquake events, facilitating timely warnings. F/O DAS technology boasts distinct advantages in earthquake detection due to its capacity to capture a broad spectrum of seismic signals, ranging from low-frequency tectonic shifts to high-frequency ground vibrations. The effectiveness of F/O DAS measurements relies on proper coupling, ensuring the efficient transfer of acoustic signals to the optical fiber, thereby ensuring precise detection and interpretation of seismic activity.

At 4:17 a.m. on Feb. 6, 2023, a magnitude-7.8 earthquake struck near Pazarcık City in south-central Türkiye, followed by a magnitude-7.5 event about 9 hours later. In this report, scientists from Türkiye explain what happened, including the complexity of the rupture itself, ground motion, building codes, and damages.

The Ganos Fault MONGAN earthquake monitoring network data presents significant opportunities and challenges for earthquake detection, location and magnitude calculations, source mechanism solutions, and discovery of fault zone waves. This study consists mostly of primary data analysis and seismological evaluations. While stations located in a local area allow the discovery of earthquakes at micro earthquake level, they create significant difficulties in determining the source parameters of these earthquakes. Extracting small earthquakes from continuous data shows that special strategies need to be developed. Network data revealed the presence of many earthquakes with magnitude M

The scope of the study is to determine transtensional and transpressional features along the North Anatolian Fault beneath the Sea of Marmara, using seismic and geodetic data. For this purpose, focal mechanisms of small size NAF earthquakes, recorded by broadband stations and OBSs, have been derived and used as a tool to identify the transtensional and transpressional features. The focal mechanisms of: (1) small to moderate size events are obtained by the CMT inversion technique of Kuge (2003), using onshore waveform data from 2002?2015, (2) micro-earthquakes are obtained using the technique of Horiuchi (2015), using offshore waveform data recorded by 15 OBS stations from 2015?2016. Furthermore, published GPS velocities are used to determine the style of faulting and strain rates. The geodetic horizontal crustal strain rates are determined at equally spaced grid points by interpolating northing and easting components of the 112 GPS vectors from 1994?2013. The results indicate that extensional and strike-slip style deformation dominates the region, while contractional features are rare. Significant extension is observed in Çınarcık Basin and the area between Marmara Island and Central Basin. Yalova-Çınarcık region shows predominantly N-S extension while the Çınarcık Basin events show NE-SW extension. Compressional or transpressional features are derived to the west of Marmara Island and Ganos and in the Central segment extending from Central Basin toward Çınarcık Basin. The GPS strain rate results point out the highest values, 24 × 10?8/year, in Çınarcık Basin, while the lowest values, 11 × 10?8/year, are observed in Central Marmara. The highest strain rates in both edges of the fault segment in Çınarcık Basin can be indicative of a steadily creeping fault segment. In turn, lower strain rates in the Central Marmara region suggest that this segment of the NAF is locked.

SUMMARY The offshore part of the North Anatolian Fault (NAF) beneath the Marmara Sea is a well-known seismic gap for future M > 7 earthquakes in the sense that more than 250 yr have passed since the last major earthquake in the Central Marmara region. Although many studies discussed the seismic potential for the future large earthquake in this region on the basis of historical record, geodetic and geological observations, it is difficult to evaluate the actual situation on the seismic activity and structure along the NAF beneath the Marmara Sea due to the lack of ocean bottom seismic observations. Using ocean bottom seismometer observations, an assessment of the location of possible asperities that could host an expected large earthquake is undertaken based on heterogeneities in the microseismicity distribution and seismic velocity structure. Specifically, seismic tomography and precise hypocentre estimations are conducted using offshore seismic data whose recording period is 11 months. About five times more microearthquakes are detected with respect to events recorded in a land-based catalogue. A comparison with previously published results from offshore observation data suggests that the seismicity pattern had not changed from 2014 September to 2017 May. The location accuracy of microearthquakes is greatly improved from only the land-based earthquake catalogue, particularly for depth direction. There are several aseismic and inactive zones of microearthquake, and the largest one is detected using land-based seismic observation, whereas other zones are newly detected via offshore observations. The obtained velocity model shows a strong lateral contrast, with two changing points. The western changing point corresponds to a segmentation boundary, where the dip angle of the NAF segments changed. High-velocity zones from tomographic images are characterized by low seismicity eastward of the segment boundary. To the east of 28.50°E, the high-velocity zone becomes thicker in the depth direction and is characterized by low seismicity. Although the low seismic activity alone could be interpreted as both strong coupling and fully creeping, the high-velocity features at the same can be concluded that these zones are consist of brittle material and strong coupling. From comparison with other geodetic and seismic studies, we interpret these zones as locked zones that had been ruptured by the past large earthquakes and could be ruptured by future ones. These zones might accumulate strain since the main shock rupture associated with the 1766 May Ms 7.3 earthquake, the latest major earthquake in this region.

of Comfort Muslims (1887) by İsmail Gaspıralı, Imagined Life (1898) by Hüseyin Cahit Yalçın, A Very Awake Sleep (1913) by İsmail Hakkı Kılıçoğlu, Rûşeni's Dream (1915/1916) by Hasan Ruşenî Barkın and Progress in Dream and View Islamic Civilization (1915/1916) by Molla Davutzade Mustafa Nazım Erzurumî.During this review; the propositions of the works concerning philosophy were listed, one of these propositions was chosen as an example and evaluated (in terms of realization, justification and usefulness), its main ideas were summarized.Evaluated utopian elements are as follows; abolition of the grand viziership, independence of the judiciary, women getting a share of their husbands' income, abolishing private property, spreading the duty of defense to the public, gathering of Muslim countries under the name of the Allied States of Islam, preventing freedom of religion and thought.Finally, in the conclusion, these works were compared with their important points and a general evaluation was made.

A Mw 6.8 earthquake struck Western Turkey and Eastern Greece that occurred on October 30, 2020 in Kupdast Gulf. The earthquake epicentre is located north of Samos Island and the focal mechanism solution shows that a normal fault was reactivated. The main shock and aftershock analysis imply that the large earthquake occurred on a north dipping normal fault which might be the western continuation of the Efes Fault in Western Turkey. We propose that the western continuation of the Efes Fault steps over right somewhere in northeast of Samos Island and continues further west along the northwest margin of the island, in the form of a transfer fault between two segments. The aftershock distribution shows that both the western segment and the transfer fault were reactivated during the 30 October 2020 earthquake. This fault geometry can be compared with the E-W trending Gediz Graben where the southern boundary fault steps over right around Turgutlu and continues further west in Manisa. The historical records show that the source region and its vicinity is susceptible to frequent large earthquakes taking place on normal and strike-slip faults. The stress tensor inversion of the focal mechanisms of 55 aftershocks covering the source area shows dominant normal faulting mechanism which suggests NNE-SSW extensional stress regime in the region.

Başlığından da anlaşılacağı üzere kitap bilgi felsefesini konu edinmekte, bu konuyu düşünür açısından Molla Sadra ile, mesele açısından ise bilen ve bilinen ilişkisi ile sınırlandırmaktadır. Kitapta meselenin kronolojik arka planı olarak Yunan ve İslam düşüncesinde bilen ve bilinen ilişkisi, tematik arka planı olarak da Molla Sadra’nın varlık felsefesi aktarılmaktadır. Kitabın odak noktası, Molla Sadra’nın şu görüşüdür: Bilgi, bilen ve bilinenin birleşmesi yoluyla gerçekleşir.

In the Aegean Sea, the western part of Gökova Gulf, Kos and Bodrum were struck by a 6.6 (Mw) earthquake on July 20, 2017. The fault plane solution for the main shock shows an E-W striking normal type fault with approximately N-S (N4°E) tensional axis (T-axis). Fault plane solutions of 33 aftershocks show two groups of normal type fault with E-W and NE-SW to ENE-WSW orientations. The inversion of the focal mechanisms of the aftershocks yields two different normal faulting stress regimes: one is characterized by an approximately N-S (N5°E) σ3 axis (minimum horizontal stress axis). This extension is obtained from 13 focal mechanisms of aftershocks with approximately E-W direction. The other is characterized by approximately NW-SE (N330°E) σ3 axis. The latter is calculated from 21 seismic faults of aftershocks with approximately NE-SW direction. These aftershocks occurred on relatively small-scale faults that were directed from NE-SW to ENE-WSW, and possibly contributed to expansion of the basin in the west. The 24 focal mechanisms of earthquakes which occurred since 1933 in and around Gökova Basin are introduced into the inversion analysis to obtain the stress state effective in a wider region. The inversion yields an extensional stress regime characterized by an approximately N-S (N355°E) σ3 axis. The E-W directional metric faults, measured in the central part of Gökova Fault Zone bordering the Gökova Gulf in the north, also indicate N-S extension. The NE-SW extension obtained from NE-SW aftershocks appears to be more local and is responsible for the expansion of the western part of the asymmetric Gökova Basin. This N-S extension which appears to act on a regional-scale may be attributed to the geodynamic effects related to the combined forces of the southwestward extrusion of Anatolia and the roll-back process of African subduction beneath Anatolia.

The 30 October 2020 Samos earthquake (Mw 7.0) ruptured an east–west striking, north dipping normal fault located offshore the northern coast of Samos Island, previously inferred from the bathymetry and regional tectonics. This fault, reported in the fault-databases as the North Samos and/or Kaystrios Fault, ruptured with almost pure dip-slip motion, in a region where both active extension and strike-slip deformation coexist. Historical information for the area confirms that similar ~ Mw7 events had also occurred in the broader Samos area, though none of the recent (last ~ 300 years) mainshocks appears to have ruptured the same fault. The spatial and temporal distribution of relocated aftershocks indicates triggering of nearby strike-slip and normal fault segments, situated in the areas where static stress has increased due to the mainshock generation. The relocated aftershocks and the slip model indicate that the sequence ruptured the upper crust (mainly the depth range 3–15 km). The top of the rupture plane nearly reached the sea bottom, located at a depth of < 1 km. Slip is confined in mainly two asperities, both located up-dip from the hypocenter and at shallow depths. The average displacement is ~ 1 m and the peak slip is ~ 3.5 m for a shear modulus of 3.2e10 N/m2. While it is difficult to constrain the rupture velocity in the inversions, the model suggests a slow rupture speed of the order of 2.2 km/s. The resolved source duration is ~ 16 s, compatible with the ~ 32 km length of the fault that ruptured.

In this study, we retrieved the finite source characteristics of the October 23, 2011 Van earthquake (Mw 7.1) using the teleseismic waveforms to focus on the source location. The outstanding off-fault aftershock sequence of the Van mainshock was readily explained by calculating the Coulomb stress changes imparted to the surrounding crust. This may be accomplished through finite source modelling to examine the stress interaction between the fault, ruptured by the Van mainshock, and the surrounding fault(s) triggered by the same mainshock. In addition, to provide further support for the Coulomb failure stress changes in the off-fault area, centroid moment tensor (CMT) inversion of the off-fault aftershocks was performed and stress tensors were derived from their focal solutions. This identified the dominant fault slip, the constraints of the crustal stress fields and illuminated the crustal nature of the stress interaction. The off-fault aftershocks showed a strike-slip stress regime in rotational (to NW) and non-rotational (to N) stress fields of the upper and lower crusts, respectively. However, this was inconsistent with a horizontal compressional stress direction striking to the north. This suggests that a local source and/or rotation of lateral variation in stress magnitudes in crustal and sub-crustal structures strongly perturbed the regional stress field. It was also evident that these strike-slip aftershocks increased the intensity of stress in an off-fault area, NE of the source rupture. This revealed a uniquely triggered strike-slip motion, activated and rooted in the weak lower crust. We conclude that the Van mainshock rupture source area, associated with the stress changes imparted to the surrounding crust, had undergone anomalous modifications to generate distinctive off-fault aftershock responses in the entire crust, and also triggered and loaded the weak lower crust. We hypothesize that the strike-slip motion, the so called "transfer fault", as a distinctly triggered slip event, was generated or selectively activated by subcrustal ductile processes in the absence of mantle lid beneath the study area. However, local slab fragmentation, tearing and cold mantle beneath the study area lead to paradigm changes in interpreting the strike-slip motion and subcrustal deformation. The presence of a small piece of oceanic lithosphere, consistent with fragmented, torn slab and cold mantle, may be an alternative hypothesis that remains to be tested. The Van earthquake, combined with careful examination of associated off-fault aftershocks, revealed new information about stress field constraints on subcrustal deformation. This investigation also provided insights into an important role of stress interaction, with a newly discovered transfer fault within the offfault area, which extends through the entire crust beneath Lakes Van and Ercek areas.

Imaging and characterizing transform fault sections that are capable to produce large earthquakes is crucial for evaluating seismic hazard and subsequent risk for nearby population centers. The Marmara Fault near the megacity of Istanbul is one of the best defined seismic gaps in the world and its complexity is captured by seismological, geodetic and geological data. A local dense seismic array (MONGAN) provides a high resolution data set allowing to image the Ganos fault separating two different geological units in the western Marmara region. First results of the waveform analysis from this array present systematic early-phase arrivals at the seismic stations located on the northern block of the Ganos fault which comprises geological units including older and more compact materials than that of the southern block. This difference in the arrival times causes the earthquake epicenters to shift further north than the real locations. In this preliminary results, the early-arrivals will be evaluated according to source azimuths and distances, and possible earth models and wave paths will be discussed. The results have implications for rupture directivity during future earthquakes as input for hazard and risk models for the Marmara region.

SUMMARY The Central Marmara Sea region hosts the northwestern branch of the North Anatolian Fault Zone (NAFZ) with its known seismic gap between the 1912 Ganos (Mw 7.2) and 1999 Izmit (Mw 7.4) major devastating earthquakes and thus poses a significant seismic hazard potential for the megacity Istanbul. The 26 September 2019 Mw 5.7 Silivri High-Kumburgaz Basin (central Marmara Sea) earthquake ruptured a thrust fault with a minor strike-slip component at the north of the eastern end of this gap relatively in the shallow depth (h= 8 km) range. Thus, in this study, we examine source properties of the main shock activity and coseismic behaviour of the failure, and the pattern of post-seismic deformation based on the aftershock distribution to have an insight into the role of the subsidiary and main fault structures on the crustal kinematics along this complicated branch of the NAFZ. The relocated epicentres are aligned in the E–W direction and tend to propagate towards the segments to the east of the main shock. The detected aftershock activity appears to focus on the east side of the main shock and almost no seismic activity was observed to the west of the epicentre. Independent investigations from coda-wave fitting, point-source, and finite-fault slip modelling agree on the moment magnitude of Mw5.7 for the 26 September 2019 main shock. The kinematic rupture model of this event implied that the main rupture nucleated around the hypocentre, and then propagated bilaterally along the E–W direction but with significant progress towards the east. The distribution of the slip vectors indicates that the rupture evolved on a dextral thrust fault plane. The spatio-temporal behaviour of the overall aftershocks sequence, their focal mechanism solutions and our kinematic slip model clearly shows that the existing secondary structures developed in simple shear dextral deformation are likely responsible for the main shock activity. We conclude that such type of deformation model results in a motion in response to the thrust faulting with strike-slip component with an N89°W (271°) orientation and 33°NE dipping at left stepover transpressional region on the NAFZ.

The offshore part of the North Anatolian Fault (NAF) beneath the Marmara Sea is a well-known seismic gap for future M > 7 earthquakes in the sense that more than 250 years have passed since the last major earthquake in the Central Marmara region. Here, an assessment on the location of possible asperities to host the expected next large earthquake is done based on the heterogeneities on the seismic velocity structure. Using long-term ocean bottom seismograph (OBS) observation data, seismic tomography and precise hypocenter estimations have been conducted. As a result, about five times more microearthquakes than the events in a land-based catalog has been detected. A comparison with previously published results suggests that the seismicity pattern has not changed during the three years period between Sep. 2014 and Jun. 2017. The obtained velocity model shows strong lateral contrast whose changing points locate at 28.10°E and 28.50°E. The western corner of the area (28.10°E) corresponds to a segmentation boundary where the dip angle of the NAF segments changed. The high velocity zones in the tomographic images are characterized by low seismicity eastward from the segment boundary at 28.10°E. Eastern 28.50°E, the high velocity zone becomes thicker in the depth direction. These zones are interpreted as asperities to be ruptured by the next large earthquake which are possibly accumulating strain since the mainshock rupture associated with the May 1766 Ms7.3 earthquake.

The June 12, 2017 Karaburun-Lesvos (North Aegean Sea) earthquake occurred along the NW-SE trending Lesvos fault, along the southern strand of the North Anatolian Fault Zone. In the present study seismotectonic aspects of the 2017 Karaburun-Lesvos earthquake and its aftershock sequence are studied. A rupture model based on finite source analysis of the teleseismic waveforms has shown that the earthquake was associated with a failure of single asperity. About 5 days after the mainshock a temporary seismic network of 8 broadband stations (Real-time Aftershock Forecasting in Turkey, RAFT) had been deployed along the Turkish Aegean coast to enhance the existing regional seismic monitoring and the acquired data have been used to relocate the aftershocks. The temporary deployment significantly improved the aftershock detection capacity and resulted in more precise locations. Prior to the monitoring enhancement a single widespread aftershock cluster was observed; however, the relocated aftershocks, augmented by the RAFT stations, identified two distinct spatially isolated clusters. The first day of the aftershock sequence has been used for retrospective real-time aftershock forecasting up to 7 days following the mainshock. Our results indicate that with a method developed by Omi et al (2013) can be used forecasting aftershocks over a week period successfully employing incompletely detected aftershocks occurred in the first day following the mainshock. Stress tensor analysis of the 33 aftershock source mechanisms has shown local dominance of the extensional tectonics with azimuth and plunge pairs for the three principal stress axes as sigma(1), sigma(2) and sigma(3) are (255 degrees; 76 degrees), (131 degrees; 8 degrees) and (39 degrees; 11 degrees), respectively. Coulomb stress changes imparted by the mainshock onto the nodal planes of the aftershocks show that similar to 67% of the 33 aftershocks have been exposed to positive stress change at least on one of the nodal planes.

Beneath the Marmara Sea, Turkey, the Main Marmara Fault (MMF), the offshore part of the North Anatolian Fault (NAF), is a well-known seismic gap for future M > 7 earthquakes. However, its detailed fault geometry and microearthquake activity have been debated for several decades. Using data acquired from long-term ocean bottom seismograph (OBS) observations, we made precise hypocenter estimations based on 3-D Vp and Vs velocity structures and assessed the fault geometry beneath the western and central parts of the MMF. The results indicate a segmentation boundary between the near-vertical western part and the south-dipping eastern part located around 28.10 degrees E. Enriched OBS locations indicate microseismicity along both the inner and outer boundary faults of the Central Basin, especially on the western side. A comparison with previously published results suggests that the seismicity pattern has not changed for at least two years, between 2014 and 2016. Using a combined dataset of this and previous studies, lateral variations in the dip angle along the MMF fault segment from 27.4 degrees E to 28.8 degrees E were investigated. Based on this, we depicted on-fault seismicity along the MMF and defined three inactive areas of microseismicity. Two are located in the western segment, corresponding to the rupture area of the 1912 Ms. 7.4 earthquake, and the other, the largest, is located on the eastern segment. From a comparison of previous seismic and geodetic studies, it is considered that this area is a fully locked zone and has the potential for large earthquakes. Having compared the difference between hypocenter locations determined from OBSs and land-based stations, it is proposed that the epicentral locations of the mainshock and aftershocks of the September 26, 2019, M 5.7 earthquake are located much closer to the MMF than locations reported from only land-based results.

Article Commentary| January 07, 2020 Comment on “An Alternative View of the Microseismicity along the Western Main Marmara Fault,” by E. Batsi et al. Yojiro Yamamoto; Yojiro Yamamoto * 1Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Yokohama, Japan *Corresponding author: yamamotoy@jamstec.go.jp Search for other works by this author on: GSW Google Scholar Ali Pinar; Ali Pinar 2Kandilli Observatory and Earthquake Research Institute (KOERI), Bogazici University, Istanbul, Turkey Search for other works by this author on: GSW Google Scholar Dogan Kalafat; Dogan Kalafat 2Kandilli Observatory and Earthquake Research Institute (KOERI), Bogazici University, Istanbul, Turkey Search for other works by this author on: GSW Google Scholar Narumi Takahashi; Narumi Takahashi 1Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Yokohama, Japan Search for other works by this author on: GSW Google Scholar Haluk Ozener; Haluk Ozener 2Kandilli Observatory and Earthquake Research Institute (KOERI), Bogazici University, Istanbul, Turkey Search for other works by this author on: GSW Google Scholar Yoshiyuki Kaneda Yoshiyuki Kaneda 3Institute of Education, Research and Regional Cooperation for Crisis Management Shikoku, Kagawa University, Takamatsu, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information Yojiro Yamamoto * 1Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Yokohama, Japan Ali Pinar 2Kandilli Observatory and Earthquake Research Institute (KOERI), Bogazici University, Istanbul, Turkey Dogan Kalafat 2Kandilli Observatory and Earthquake Research Institute (KOERI), Bogazici University, Istanbul, Turkey Narumi Takahashi 1Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Yokohama, Japan Haluk Ozener 2Kandilli Observatory and Earthquake Research Institute (KOERI), Bogazici University, Istanbul, Turkey Yoshiyuki Kaneda 3Institute of Education, Research and Regional Cooperation for Crisis Management Shikoku, Kagawa University, Takamatsu, Japan *Corresponding author: yamamotoy@jamstec.go.jp Publisher: Seismological Society of America First Online: 07 Jan 2020 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2020) 110 (1): 381–382. https://doi.org/10.1785/0120180317 Article history First Online: 07 Jan 2020 Connected Content Companion: Reply to “Comment on ‘An Alternative View of the Microseismicity along the Western Main Marmara Fault’ by E. Batsi et al.” by Y. Yamamoto et al. Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Yojiro Yamamoto, Ali Pinar, Dogan Kalafat, Narumi Takahashi, Haluk Ozener, Yoshiyuki Kaneda; Comment on “An Alternative View of the Microseismicity along the Western Main Marmara Fault,” by E. Batsi et al.. Bulletin of the Seismological Society of America 2020;; 110 (1): 381–382. doi: https://doi.org/10.1785/0120180317 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Two independent studies that have used data recorded by two independent nearby dense ocean‐bottom seismographic (OBS) networks deployed in the Sea of Marmara have recently published their results (Yamamoto et al., 2017; Batsi et al., 2018, hereafter mentioned as “their article”). Despite the proximity of the two OBS networks, the results presented in the two articles have large misfits (fig. 15 of their article). In their article, they have concluded that both results are “internally consistent.” However, we cannot agree with this conclusion. We comment on their article considering the causes for such large discrepancies.... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.