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As the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes in the region, the Kandilli Observatory and Earthquake Research Institute (KOERI) has a long history in seismic observation, which dates back to the installation of its first seismometers soon after the devastating Istanbul earthquake of 10 July 1894. For over a century, since the deployment of its first seismometer, the KOERI seismic network has grown steadily in time. In this article, we present the KOERI seismic network facilities as a data center for the seismological community, providing data and services through the European Integrated Data Archive (EIDA) and the Rapid Raw Strong-Motion (RRSM) database, both integrated in the Observatories and Research Facilities for European Seismology (ORFEUS). The objective of this article is to provide an overview of the KOERI seismic services within ORFEUS and to introduce some of the procedures that allow to check the health of the seismic network and the quality of the data recorded at KOERI seismic stations, which are shared through EIDA and RRSM.

A submarine area close to the Turkish and Greek border between the cities of Samos-Greece and Seferihisar-Turkey has been shaked on October 30, 2020 by a Mw = 6.9 earthquake. In this study, the finite source mechanism of the Samos earthquake was investigated using geodetic methods and the coseismic behavior of the earthquake was modeled. The observed coseismic displacements at 62 sites were inverted for the fault geometry and the slips. The mainshock did not generate an on-land surface rupture. However, the uniform slip modeling shows a finite source of 43.1 km long and 16 km wide rupture, which slips 1.42 m along a north dipping normal fault extending from the Aegean Sea floor to a depth down to similar to 13 km. While the uniform slip model is consistent with the seismological solutions and provides a sufficient fit to the far field coseismic offsets, a distributed slip model is necessary to account for the near field coseismic displacements.

We analyzed GPS data to investigate the source parameters of the 2014 North Aegean earthquake (Mw 6.9). We simultaneously inverted strike, dip, rake, average slip, moment, size, and location of the mainshock rupture using coseismic displacements. We also investigated static stress change associated with the mainshock and its influence on aftershock activity. Previous solutions of focal mechanism showed that mainshock has a nearly pure strike-slip nature. Our results also indicate that the mainshock has a right lateral strike-slip mechanism with a substantial extensional component. Average coseismic slips are 48 cm and 25 cm on the horizontal and vertical axis, respectively. Coseismic displacements reach up to 51.35 ± 4.55 mm at ~60 km from the hypocenter (LEMN station). It appears that the mainshock ruptured a fault section approximately 28 km deep and 70 km long and generated a stress drop along the ruptured segment ranging between 3 and 10 bar, with a stress increase of 3 bar at the edges of the rupture. Aftershocks were distributed to a broader area as coseismic stress increase affected a 200-km-long section of the western North Anatolian Fault.

In the past 1500 years, seven sequences of significant earthquakes have occurred on a 160-km-long segment of the North Anatolian Fault zone (NAFZ) centered on Istanbul. The most recent of these sequences will be complete with the future occurrence of one or more Mw ≥ 7.0 earthquakes near the city. From a summation of the seismic moment released by historical earthquakes between 500 and 2000 CE we calculate a mean slip deficit rate of 9.9 mm/year. Our moment summation procedure sums the seismic moment associated with known historical earthquakes in the past 1500 years based on rupture length and assumed seismogenic depth. We observed that in the 1999 Izmit earthquake, strongly coupled fault patches were associated with the highest co-seismic slip. In our calculated map of present-day slip-potential, we recognize several such patches from their low present-day rate of microseismicity, e.g. segments beneath the Kumburgaz and Eastern (Cinarcik) Marmara Basins. In contrast, intervening weakly coupled patches host high present-day background seismicity, e.g. the segment beneath the Western (Tekirdag) Basin. This lends credibility to an interpretation of future earthquakes occurring in three seismogenic segments of the NAFZ corresponding to three deep basins in the Sea of Marmara. The present-day slip deficits reach up to 1.7 m beneath the Western (Tekirdag Basin) segment, and 4.0 m and 5.4 m beneath the Central (Central High and Kumburgaz Basin) and Eastern (Cinarcik Basin) segments, respectively. These segments most recently ruptured in August 1766, May 1766 and October 1509 and currently have a potential to generate Mw 7.2, Mw 7.4 and Mw 7.5, earthquakes respectively. Although contiguous ruptures have not occurred historically, ruptures of contiguous segments could occur as a Mw 7.5 earthquake in the west, or a Mw 7.6 earthquake in the east or as a single through-going Mw 7.7 rupture.

The survival of humanity is dependent on the survival of forests and the ecosystems they support, yet annually wildfires destroy millions of hectares of global forestry. Wildfires take place under specific conditions and in certain regions, which can be studied through appropriate techniques. A variety of statistical modeling methods have been assessed by researchers; however, ensemble modeling of wildfire susceptibility has not been undertaken. We hypothesize that ensemble modeling of wildfire susceptibility is better than a single modeling technique. This study models the occurrence of wildfire in the Brisbane Catchment of Australia, which is an annual event, using the index of entropy (IoE), evidential belief function (EBF), and logistic regression (LR) ensemble techniques. As a secondary goal of this research, the spatial distribution of the wildfire risk from different aspects such as urbanization and ecosystem was evaluated. The highest accuracy (88.51%) was achieved using the ensemble EBF and LR model. The outcomes of this study may be helpful to particular groups such as planners to avoid susceptible and risky regions in their planning; model builders to replace the traditional individual methods with ensemble algorithms; and geospatial users to enhance their knowledge of geographic information system (GIS) applications.

Strong ground motion records and free open access to strong‐motion data repositories are fundamental inputs to seismology, engineering seismology, soil dynamics, and earthquake engineering science and practice. This article presents the current status and outlook of the Observatories and Research Facilities for European Seismology (ORFEUS) coordinated strong‐motion seismology services, namely the rapid raw strong‐motion (RRSM) and the engineering strong‐motion (ESM) databases and associated web interfaces and webservices. We compare and discuss the role and use of these two systems using the Mw 6.5 Norcia (Central Italy) earthquake that occurred on 30 October 2016 as an example of a well‐recorded earthquake that triggered major interest in the seismological and earthquake engineering communities. The RRSM is a fully automated system for rapid dissemination of earthquake shaking information, whereas the ESM provides quality‐checked, manually processed waveforms and reviewed earthquake information. The RRSM uses only data from the European Integrated Waveform Data Archive, whereas the ESM also includes offline data from other sources, such as the ITalian ACcelerometric Archive (ITACA). Advanced software tools are also included in the ESM to allow users to process strong‐motion data and to select ground‐motion waveform sets for seismic structural analyses. The RRSM and ESM are complementary services designed for a variety of possible stakeholders, ranging from scientists to the educated general public. The RRSM and ESM are developed, organized, and reviewed by selected members of the seismological community in Europe, including strong‐motion data providers and expert users. Global access and usage of the data is encouraged. The ESM is presently the reference database for harmonized seismic hazard and risk studies in Europe. ORFEUS strong‐motion data are open, “Findable, Accessible, Interoperable, and Reusable,” and accompanied by licensing information. The users are encouraged to properly cite the data providers, using the digital object identifiers of the seismic networks. © 2021 Seismological Society of America ISSN:0895-0695 ISSN:1938-2057

Thanks to both technological evolution and analysis improvement in the past decades, space geodesy can now monitor crustal movements of a few millimeters over time opening new prospects for the study of earthquakes. However, fully exploiting the potential of geodetic measurements is subject to their further integration with seismological analysis and requires the development of a multidisciplinary approach. The new joint IAG-IASPEI sub-commission on Seismogeodesy aims to facilitate the cooperation between the geodetic and the seismological communities in order to improve our current understanding of the different processes leading to earthquakes. The new Seismogeodesy sub-commission will focus on both observational challenges and theoretical aspects. Particular effort will be dedicated to identifying gaps of knowledge and opportunity for progress. Specifically, the sub-commission will:* actively encourage the cooperation between all geoscientists studying the plate boundary deformation zones, by promoting the exploitation of synergies between different fields;* work to reinforce collocated and integrated geodetic and seismological monitoring of seismically active areas, inland and off-shore by increasing and/or developing infrastructures dedicated to broadband observations from the seismic wave band to the permanent displacement;* be a reference group for the integration of the most advanced geodetic and seismological techniques by developing consistent methodologies for data reduction, analysis, integration, and interpretation;* act as a forum for discussion and scientific support for international geoscientists investigating the kinematics and mechanics of the plate boundary deformation zone;* promote the use of standard procedures for geodetic data acquisition, quality evaluation, and processing, particularly GNSS data and InSAR data;* promote earthquake geodesy, the study of seismically active regions with large earthquake potential, and geodetic application to early warning system of earthquakes and tsunamis for hazard mitigation;* promote the role of geodesy in tectonic studies for understanding the seismic cycle, transient and instantaneous deformation, and creeping versus seismic slip on faults.* facilitate and stimulate the integrated exploitation of large data sets, using Machine Learning and Data Mining* support the organization of periodic workshops, meetings, summer schools with special emphasis on interdisciplinary research and interpretation and modeling issues* help to the emergence of a new generation of researchers in Seismogeodesy worldwideWe invite any researcher interested in Seismogeodesy to join us and have a fruitful discussion in front of our poster.

The coastal areas are being destroyed due to the usage that effect the natural balance. Unconsciously sand mining from the sea for nearshore nourishment and construction uses are the main ones. Physical interferences for mining of sand cause an ecologic threat to the coastal environment. However, use of marine sand is inevitable because of economic reasons or unobtainable land-based sand resources. The most convenient solution in such a protection–usage dilemma is to reduce negative impacts of sand production from marine. This depends on the accurate determination of criteriaon production place, style, and amount of sand. With this motivation, nearshore geodedic surveying studies performed on Kilyos Campus of Bogazici University located on the Black Sea coast, north of Istanbul, Turkey between 2001-2002. The study area extends 1 km in the longshore. Geodetic survey was carried out in the summer of 2001 to detect the initial condition for the shoreline. Long-term seasonal changes in shoreline positions were determined biannually. The coast was measured with post-processed kinematic GPS. Besides, shoreline change has studied using Landsat imagery between the years 1986-2015. The data set of Landsat 5 imageries were dated 05.08.1986 and 31.08.2007 and Landsat 7 imageries were dated 21.07.2001 and 28.07.2015. Landcover types in the study area were analyzed on the basis of pixel based classification method. Firstly, unsupervised classification based on ISODATA (Iterative Self Organizing Data Analysis Technique) has been applied and spectral clusters have been determined that gives prior knowledge about the study area. In the second step, supervised classification was carried out by using the three different approaches which are minimum-distance, parallelepiped and maximum-likelihood. All pixel based classification processes were performed with ENVI 4.8 image processing software. Results of geodetic studies and classification outputs will be presented in this paper.

Strain analysis is one of the methods for the kinematic analysis of the repeated geodetic measurements. In order to derive strain accumulation in Marmara Region, different institutions carried out several Global Positioning System (GPS) campaigns in 1999 and 2006. The GPS campaigns were performed on the geodetic network which cover the provinces: Kirklareli, Tekirdag, Bursa, Bilecik and Adapazari. Then, the displacements of the network stations were estimated by means of analysing the GPS space geodetic measurements. For the assessment of the datum differences between 1999 and 2006 on the station coordinates, 3-D Helmert transformation was applied to the coordinates of each 1999 and 2006 datum. Then, a global test was introduced to determine the significant deformation which occurred in the geodetic GPS network. Strain accumulation with a finite element model was then computed. First, triangles were constructed for the whole network with the Delaunay method. Hereafter, strain parameters were calculated for each triangle. Maximum values of strain accumulation were found around the surroundings of Marmara Ereglisi and Izmit, whereas minimum values are around Istanbul.

The North Anatolian Fault (NAF) represents one of the most seismically active transform zones on Earth. It is characterized by high rates of crustal deformation that generate destructive earthquakes. These rates are induced by convergence of the northward-migrating Arabian and African plates with respect to the stable Eurasian plate. Therefore, the NAF represents a natural earthquake laboratory with a wide range of earthquake sizes (M ≤ 7.9) to investigate by using interdisciplinary approaches (seismological, magnetism, geological, gravitational, and geodetic studies). In this study, we compare the results of an analysis of b-values from seismicity and GPS (Global Positioning System) measurements of the strain rate to understand their coupling in terms of faulting and earthquake hazard implications. In particular, this comparison allows investigation of the spatial correlation between b-value and strain rate maps and is thus able to locate fault segments that have a high potential of generating large earthquake(s). b-Values range from 0.5 to 1.5 along the central NAF. The maximum principal strain rates are positive (tensile), and the minimum principal strain rates are negative (compressive). The surface strain is positive, showing that tensile strain is predominant in areas with high strain rates, consistent with the trend of the corresponding stresses.

WOS: 000450847400001, Greek-Turkish boundary near the cities Kos and Bodrum has been shaken on July 20, 2017 by a Mw6.6 earthquake. The mainshock is located offshore and did not generate an on-land surface rupture. Analyzing pre-and post-earthquake continuous/survey-type static GPS observations, we investigated co-seismic surface displacements at 20 sites to characterize source parameters and slip-distribution of the mainshock. Fault plane solutions as well as co-seismic slip distribution have been acquired through the inversion of co-seismic GPS displacements modeling the event as elastic dislocations in a half space. Fault plane solution shows a southward dipping normal-type fault segment extending a depth down to similar to 12 km, which remains within the brittle upper crust. Results from the distributed slip inversion show that the mainshock activated a similar to 65 km fault section, which has three high slip patches, namely western, central and eastern patches, where the coseismic slips reach up to 13, 26, and 5 cm, respectively. This slip pattern indicates that the pre-earthquake coupling, which is storing the slip deficit, occurred on these three patches., Research Foundation of Afyon Kocatepe University [17.FEN.BIL.35], This work was supportted by Research Foundation of Afyon Kocatepe University [project number 17.FEN.BIL.35].

Space-based tectonic studies on the western part of the North Anatolian Fault Zone (NAFZ) have been conducted over two decades. After the August 17, 1999, Izmit earthquake ( M w = 7.4), this region attracted greater scientific interest, and the collected data became more valuable. The Geodesy Department of the Kandilli Observatory and Earthquake Research Institute (KOERI) at Bogazici University established three micro-geodetic networks to the east of Akyazi, east of Iznik, and west of Lake Sapanca in the eastern part of the Marmara region; GPS data have been continually collected at these locations since 1994. The NAFZ branches out in the western part of the Marmara region and extends up to the Aegean Sea. Segments of the fault passing through the Marmara Sea are considered active, and this has increased concern regarding imminent earthquakes. Conventional geodetic measurements made between 1990 and 1994 are not sufficient for monitoring small movements. However, GPS has played a very important role in detecting such deformations in the area after 1994. The Iznik network, with 10 points, is bilaterally located on the Iznik-Mekece fault. Six years of GPS data for 2004–2010 collected for the monitoring of crustal deformation showed that the Iznik-Mekece fault segment moves westward at about 22 ± 1 mm/yr with respect to the Eurasia fixed reference frame. The GPS observations show that there is no strain accumulation in the area.

WOS: 000318381400003, Both seismological and geodynamic studies emphasize that the Aegean region is deforming internally mainly under pure shear stress and rotating in an anti-clockwise direction relative to the Eurasia plate. The Aegean region is seismically the most active region in western Anatolia, which comprises the Hellenic Arc, Greece, and western Turkey. Izmir is the third largest city in Turkey, with a population about 2.7 million in 2010. The Tuzla fault has a particular importance in terms of its proximity to the city of Izmir and its seismic activity. The Tuzla fault has NE-SW trending lineaments and lies between the towns of Menderes and Cape Doganbey. This study intended to investigate crustal deformation and relative displacement along the Tuzla fault and Izmir Bay by two different geodetic techniques: GPS and precise leveling. Toward this aim, a geodetic network consisting of 16 points has been established. The first GPS observation campaign and precise leveling measurements were performed in 2009, and the second set of measurements was performed in 2010. The data collected by the GPS campaigns were processed with GAMIT/GLOBK software. The displacements inferred from GPS data are between 21 mm/yr and 25 mm/yr with respect to Eurasia as the fixed reference frame. In addition, the precise leveling results show that there is a vertical displacement in the region of around 7 mm along the fault, which is higher than expected during a nine-month interval. (C) 2012 Elsevier Ltd. All rights reserved., TUBITAK-CAYDAG [108Y295]; Bogazici University Scientific Research Projects (BAP) [5056]; Geodesy Department of Kandilli Observatory; Earthquake Research Institute, The authors would like to thank the Geodesy Department of Kandilli Observatory and Earthquake Research Institute and the project's members for their support. We also thank Rob Reilinger and an anonymous reviewer for their comments and suggestions. We are grateful to the district governor of Seferihisar, officials of Izmir Metropolitan and Seferihisar Municipalities, and local people in the region for their help. Maps were drawn using GMT 4.5 (Wessel and Smith, 2001). This study was mainly supported by TUBITAK-CAYDAG under grant no. 108Y295 and Bogazici University Scientific Research Projects (BAP) under grant no. 5056.

For almost half a century, the Ismetpasa section of North Anatolian Fault (NAF) has been known to be creeping aseismically. During the past decades, there have been a number of investigations undertaken to monitor this movement using conventional surveying methods, GPS, LIDAR, and InSAR techniques. These studies have provided information on the length, depth and the rate of fault creep. We used GPS observations on a network of 5 survey points established in 1972 by the General Command of Mapping across the creeping segment to determine the present-day creep rate. This micro-geodetic network covers an area of approximately 1 km × 1 km on the 60 km long creeping section as determined from prior studies. GPS campaigns were carried out annually between 2005 and 2011. We found no evidence of a change in creep rate during this time period, consistent with some previous studies. On this portion of the creeping section, the creep rate is 7.6 ± 1 mm/yr, which is less than half of the annual average rate of relative plate velocity, indicating that significant strain is being accumulated on the fault. By comparing the present creep rate with earlier estimates, we conclude that the creep rate near Ismetpasa has been decreasing exponentially since the initial observations (1957–1969), and is likely the result of postseismic after slip following the 1944 (Mw 7.2) and/or 1951 (Mw 6.9) earthquakes that broke this segment of the fault.

The North Anatolian Fault Zone (NAFZ), which marks the boundary between Anatolia and the Eurasian plate, is one of the world's most seismically active structures. Although the eastern part of NAFZ has high seismic hazard, there is a lack of geodetic information about the present tectonics of this region. Even though many scientists would like to study this area, geographical and logistical problems make performing scientific research difficult. In order to investigate contemporary neotectonic deformation on the eastern NAFZ and in its neighborhood, a relatively dense Global Positioning System (GPS) monitoring network was established in 2003. Geodetic observations were performed in three GPS campaigns in an area of 350 km x 200 km with 12-month intervals. In addition, 14 new GPS stations were measured far from the deforming area. Since this region includes the intersection of the NAFZ and the East Anatolian Fault Zone (EAFZ), deformation is complex and estimating seismic hazard is difficult. One important segment is the Yedisu segment and it has not broken since the 1784 earthquake. After the 1992 Erzincan and 2003 Pulumur earthquakes, the Coulomb stress loading on the Yedisu segment of the NAFZ has increased significantly, emphasizing the need to monitor this region. We computed the horizontal velocity field with respect to Eurasia and strain rates field as well. GPS-derived velocities relative to Eurasia are in the range of 16-24 mm/year, which are consistent with the regional tectonics. The principal strain rates were derived from the velocity field. Results show that strain is accumulating between the NAFZ and EAFZ along small secondary fault branches such as the Ovacik Fault (OF). T.) (C) 2010 Elsevier Ltd. All rights reserved.

The Earth is being monitored every day by all kinds of sensors. This leads an overflow of data in all branches of science nowadays, especially in Earth Sciences. Data storage and data processing are the problems to be solved by current technologies, as well as by those accessing and analyzing these large data sources. Once solutions have been created for collecting, storing and accessing data, then the challenge becomes how to effectively share data, applications and processing resources across many locations. The Global Positioning System (GPS) sensors are being used as geodetic instruments to precisely detect crustal motion in the Earth’s surface. Rapid access to data provided by GPS sensors is becoming increasingly important for deformation monitoring and rapid hazard assessments. Today, reliable and fast collection and distribution of data is a challenge and advances in Internet technologies have made it easier to provide the needed data. This study describes a system which will be able to generate strain maps using data from continuous GPS stations for seismic hazard analysis. Strain rates are a key factor in seismic hazard analyses. Turkey is a country prone to earthquakes with a long history of seismic hazards and disasters. This situation has resulted in the studies by Earth scientists that focus on Turkey in order to improve their understanding of the Earth’s crust structure and seismic hazards. Nevertheless, the construction of models, data access and analysis are often not fast as expected, but the combination of Internet technologies with continuous GPS sensors can be a solution to overcome this problem. This system would have the potential to answer many important questions to assess seismic hazards such as how much stretching, squashing and shearing is taking place in different parts of Turkey, and how do velocities change from place to place? Seismic hazard estimation is the most effective way to reduce earthquake losses. It is clear that reliability of data and on-line services will support the preparation of strategies for disaster management and planning to cope with hazards.

The geotechnical monitoring played an important role in guiding the tunneling applications during the construction of IZMIR LRTS (Light Rapid Transit System) 1st stage. The purpose of this paper is to review the deformation measurements and results gathered during the construction of LRTS 1st stage tunnels. The New Austrian Tunneling concept (NATM) was used for the construction of Ucyol–Konak conventional tunnels of the system. The EPBM (Earth Pressure Balance Method) concept used in the construction of Konak–Basmane precast segmental tunnels. Both tunneling concepts required monitoring of deformations during construction as well as for a period after its completion.

WEGENER is originally the acronym for Working Group of European Geoscientists for the Establishment of Networks for Earth-science Research. It was founded in March 1981 in response to an appeal delivered at the Journées Luxembourgeoises de Geodynamique in December 1980 to respond with a coordinated European proposal to a NASA Announcement of Opportunity inviting participation in the Crustal Dynamics and Earthquake Research Program. WEGENER, during the past 32 years, has always kept a close contact with the Agencies and Institutions responsible for the development and maintenance of the global space geodetic networks with the aim to make them aware of the scientific needs and outcomes of the project which might have an influence on the general science policy trends. WEGENER was serving as Inter-commission Project 3.2, between Commission 1 and Commission 3, of the International Association of Geodesy (IAG) until 2012. Since then, WEGENER project has became the Sub-commission 3.5 of IAG commission 3, namely Tectonics and Earthquake Geodesy. In this study, we briefly review the accomplishments of WEGENER as originally conceived and outline and justify the new focus of the WEGENER consortium. The remarkable and rapid evolution of the present state of global geodetic monitoring in regard to the precision of positioning capabilities (and hence deformation) and global coverage, the development of InSAR for monitoring strain with unprecedented spatial resolution, and continuing and planned data from highly precise satellite gravity and altimetry missions, encourage us to shift principal attention from mainly monitoring capabilities by a combination of space and terrestrial geodetic techniques to applying existing observational methodologies to the critical geophysical phenomena that threaten our planet and society. Our new focus includes developing an improved physical basis to mitigate earthquake, tsunami, and volcanic risks, and the effects of natural and anthropogenic climate change (sea level, ice degradation). In addition, expanded applications of space geodesy to atmospheric studies will remain a major focus with emphasis on ionospheric and tropospheric monitoring to support forecasting extreme events. Towards these ends, we will encourage and foster interdisciplinary, integrated initiatives to develop a range of case studies for these critical problems. Geological studies are needed to extend geodetic deformation studies to geologic time scales, and new modeling approaches will facilitate full exploitation of expanding geodetic databases. In light of this new focus, the WEGENER acronym now represents, “World Earthquake GEodesy Network for Environmental Hazard Research”.

The 17 August 1999 Izmit earthquake significantly deformed the earth's crust in the Marmara Region, especially in the Golcuk–Sapanca Zone, Turkey. It broke a 150-km long segment of the northern branch of North Anatolian Fault Zone. The geodetically determined moment magnitude was M w =7.5. Global Positioning System (GPS) sites, which are a small subset of the Marmara Continuous GPS Network (MAGNET), and survey sites in the region were studied to estimate coseismic and postseismic deformations, using different methodologies with linear, quadratic and exponential kinematic models. Six GPS epochs for these sites, which were carried out before and after the 17 August 1999 Izmit earthquake, were used to define the kinematic models. The quadratic deformation model was also applied to determine the time-dependent crustal movement parameters (velocity and acceleration) of the sites, using the Kalman filter technique. In order to show the differences between the models, the estimated deformation fields on the last epoch were compared. In all models, as expected, the faults near the sites show large coseismic displacements with fault parallel direction, whereas the far sites show small coseismic displacements due to the effects of the Izmit earthquake. Each kinematic model, fitted to the epochs after the earthquake, shows different behaviour. While the linear model shows insufficient results, the nonlinear models (quadratic and exponential) give the best fitted to the postseismic deformations. As a result of Kalman filter analysis, the fault near-sites shows significant velocities with fault parallel direction, whereas the far sites have insignificant velocities. All stations have insignificant accelerations in the last epoch.

We report the results of nearly 7 years of postseismic deformation measurements using continuously recorded and survey mode GPS observations for the 1999 Izmit-Düzce earthquake sequence. Resolvable, time-dependent postseismic changes to the preearthquake interseismic velocity field extend at least as far as the continuous GPS station in Ankara, ∼200 km southeast of the Izmit rupture. Seven years after the earthquake sequence, the relative postseismic velocity across the North Anatolian Fault (NAF) reaches ∼10–12 mm/a, roughly 50% of the steady state interseismic rate, with the highest postseismic velocities within 40 km of the coseismic ruptures. We use a sequence of logarithmic time functions to fit GPS site motions. Up to three logarithmic terms with decay constants of 1, 150, and 3500 days are necessary to fit all the transient motion observed at the continuous GPS stations. The first term is required for the component of site motion parallel to the NAF at near-field sites strongly implicating rapid, shallow afterslip. The intermediate and longer-term postseismic velocity components reflect more broadly distributed strain with a symmetric double-couple pattern suggestive of either localized, deep afterslip or viscoelastic relaxation of the upper mantle and/or lower crust. In two areas (including the Marmara Sea) this pattern is superimposed on north-south extension centered on the NAF. We speculate that this extension may result from aseismic dip slip along coseismically weakened faults, driven by the background tectonic stress., Scientific and Technological Research Council of Turkey (CAYADAG Project 103Y100, EU 6), European Training Foundation (Frame FORESIGHT Project contract 511139), Scientific and Technological Research Council of Turkey (TARAL 1007 Project 105G019), National Science Foundation (U.S.) (grant EAR-0337497), National Science Foundation (U.S.) (grant EAR-0305480), National Science Foundation (U.S.) (grant INT-0001583), Natural Sciences and Engineering Research Council of Canada (Discovery grant RGPIN 261 458-07)

Both seismological and geodynamic research emphasize that the Aegean Region, which comprises the Hellenic Arc, the Greek mainland and Western Turkey is the most seismically active region in Western Eurasia. The convergence of the Eurasian and African lithospheric plates forces a westward motion on the Anatolian plate relative to the Eurasian one. Western Anatolia is a valuable laboratory for Earth Science research because of its complex geological structure. Izmir is a large city in Turkey with a population of about 2.5 million that is at great risk from big earthquakes. Unfortunately, previous geodynamics studies performed in this region are insufficient or cover large areas instead of specific faults. The Tuzla Fault, which is aligned trending NE–SW between the town of Menderes and Cape Doganbey, is an important fault in terms of seismic activity and its proximity to the city of Izmir. This study aims to perform a large scale investigation focusing on the Tuzla Fault and its vicinity for better understanding of the region's tectonics. In order to investigate the crustal deformation along the Tuzla Fault and Izmir Bay, a geodetic network has been designed and optimizations were performed. This paper suggests a schedule for a crustal deformation monitoring study which includes research on the tectonics of the region, network design and optimization strategies, theory and practice of processing. The study is also open for extension in terms of monitoring different types of fault characteristics. A one-dimensional fault model with two parameters – standard strike-slip model of dislocation theory in an elastic half-space – is formulated in order to determine which sites are suitable for the campaign based geodetic GPS measurements. Geodetic results can be used as a background data for disaster management systems.

We model the geodetically observed secular velocity field in north- western Turkey with a block model that accounts for recoverable elastic-strain ac- cumulation. The block model allows us to estimate internally consistent fault slip rates and locking depths. The northern strand of the North Anatolian fault zone (NAFZ) carries approximately four times as much right-lateral motion (24 mm/yr) as does the southern strand. In the Marmara Sea region, the data show strain accu- mulation to be highly localized. We find that a straight fault geometry with a shallow locking depth of 6-7 km fits the observed Global Positioning System velocities better than does a stepped fault geometry that follows the northern and eastern edges of the sea. This shallow locking depth suggests that the moment release associated with an earthquake on these faults should be smaller, by a factor of 2.3, than previously inferred assuming a locking depth of 15 km. Online material: an updated version of velocity-field data.

This article describes the Engineering Strong‐Motion Database (ESM), developed in the framework of the European project Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation (NERA, see [Data and Resources][1]). ESM is specifically designed to provide end users only with quality‐checked, uniformly processed strong‐motion data and relevant parameters and has done so since 1969 in the Euro‐Mediterranean region. The database was designed for a large variety of stakeholders (expert seismologists, earthquake engineers, students, and professionals) with a user‐friendly and straightforward web interface. Users can access earthquake and station information and download waveforms of events with magnitude≥4.0 (unprocessed and processed acceleration, velocity, and displacement, and acceleration and displacement response spectra at 5% damping). Specific tools are also available to users to process strong‐motion data and select ground‐motion suites for code‐based seismic structural analyses. [1]: #sec-13

The western part of North Anatolian Fault (NAF) bifurcates around Mudurnu into two fault segments: northern and southern branch. The latter bifurcates again at west of Pamukova and creates middle strand. This study aimed to analyze crustal movement along the middle strand near Iznik which is considered as inactive fault. We focused on a microgeodetic network called General Command of Mapping-Istanbul Technical University (GCM-ITU) network around this segment. In order to obtain displacement values, five campaigns performed on the network which were used in the study. The displacements of the stations were estimated relative to the fixed stations located at the south of the network. The coordinates of the stations were calculated from the triangulation measurements realized in 1941 and 1963, trilateration measurements in 1981, and GPS campaigns in 2004 and 2007. Then, mean displacements of the network ranging between 7 mm/yr and 18 mm/yr were obtained for these years. In the second part of the study, the GPS data were re-processed by adding three stations from Marmara Continuous GPS Network (MAGNET). Details of MAGNET can be found Ergintav et al. (2002). Estimated displacements were ranging between 3 mm/yr and 13 mm/yr for 2004 and 2007. TUBI station of IGS network was taken as stable.