An Approach for Rapid Assessment of Seismic Hazards in Turkey by Continuous GPS Data

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

Estimates of Seismic Potential in the Marmara Sea Region from Block Models of Secular Deformation Constrained by Global Positioning System Measurements

We model the geodetically observed secular velocity field in northwestern Turkey with a block model that accounts for recoverable elastic-strain accumulation. 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 accumulation 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.Earth and Planetary Science

WEGENER 2010

The Journal of Geodynamics is an international and interdisciplinary forum for the publication of results and discussions of solid earth research in geodetic, geophysical, geological and geochemical geodynamics, with special emphasis on the large scale processes involved

Geodetic Network Design and Optimization on the Active Tuzla Fault (Izmir, Turkey) for Disaster Management

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Seismic hazard assessment of the central North Anatolian Fault (Turkey) from GPS-derived strain rates and <i>b</i>-values

<p>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 (<i>M</i> ≤ 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 <i>b</i>-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 <i>b</i>-value and strain rate maps and is thus able to locate fault segments that have a high potential of generating large earthquake(s). <i>b</i>-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.</p