Statement of Workshop Conclusions
Thessaloniki Workshop on the Tectonics of the Northern Aegean and the Marmara Seas
Ladies and Gentlemen:
I am Prof. Eleftheria Papadimitriou, one of the conveners of the workshop in Thessaloniki. I am a Professor in the Department of Geophysics at Aristotle University of Thessaloniki.
To earth scientists, the Aegean Sea and the surrounding land areas have one of the most complex and fascinating tectonic stories of any place on Earth. The movements of the Earth's crust known as plate tectonics are conspiring to squeeze the Anatolian plate westward. The motion is mostly concentrated along major faults through the Marmara and the Northern Aegean. At the same time, the eastern Mediterranean is being subducted along the Hellenic Arc and beneath the Southern Aegean. The coupling between these two tectonic systems has produced a complex distribution of crustal faults and surface deformation that has been responsible for devastating earthquakes throughout the Aegean region. If we are to make progress in protecting society from earthquake disasters, we must understand the very basis of tectonic activity in the Aegean, the Marmara, and the surrounding areas.
The complexities of the region and the significant earthquake hazard have drawn researchers from all over the world to the Aegean. Greek and Turkish scientists, and their colleagues throughout Europe, Japan and the United States, are doing significant and important work. That so many scientists have been drawn to study the Aegean is a testament not only to the significance of the research problems, but to the hospitality and collaborative atmosphere established by Greek and Turkish hosts. We will build on these efforts and coordinate with other related initiatives.
One of the most important geologic features of Aegean tectonics is the North Anatolian Fault System, which extends from Turkey westward beneath the Marmara Sea and beneath the Northern Aegean. The North Anatolian Fault System is one of the world's major strike-slip systems. The fault itself is segmented, has at least four branches beneath the Northern Aegean, changes direction, and terminates abruptly in the Greek mainland. This system and its related secondary faults are responsible both for the devastating earthquakes in 1999 in northwest Turkey, and the recent earthquakes near Skyros Island, and are the most significant source of earthquake hazard in the region.
It is because of the complexity, regional scope and social significance of the North Anatolian Fault system that scientists have decided that a coordinated, multidisciplinary approach must be developed to study it. Such a coordinated study should be built on the scientific research that has already been completed and that which is currently underway, and should be open to worldwide collaboration so that the best science and technology can be brought to bear on research priorities. Also, it should be structured in order to recognize the interests of the Greek and Turkish people in building disaster-resilient societies.
With this open framework, a group of scientists from Greece, Turkey, the National Research Council of Italy and the United States have just completed a planning workshop in Thessaloniki, hosted by Aristotle University. Many scientists from other countries were invited, but were unable to attend because of previous commitments. The meeting was held to plan a step-by-step process that we hope will lead to a coordinated international program of research and surveys on the North Anatolian Fault System, both on land and underwater. We emphasize that this is only the first step in a progressive process. By identifying outstanding scientific issues and the potential of new observational technologies, we hope to build support from our colleagues, our scientific institutions, and our governments for a major international scientific program.
At the workshop, we reviewed existing research in the Northern Aegean and the Marmara. This helped us identify outstanding research problems. We discussed the results of recent pilot surveys that clearly show the potential of new survey technologies and observational techniques. This led to a discussion of the experiments and surveys to address the outstanding research problems. Finally, we identified steps necessary to bring our ideas for a coordinated program to our respective governments and funding institutions. We concluded with the need to convene a second meeting in the near future, and we were pleased to accept the invitation of Professor Gorur to hold a meeting in Istanbul.
My colleague, Professor Gorur, will describe the preliminary results of the workshop and some objectives for future research.
Ladies and Gentlemen:
I am Professor Naci Gorur. I am Coordinator of Marine Research, TUBITAK (Scientific and Technical Research Council of Turkey).
The Northern Aegean and Marmara Sea together represent a significant risk to our people, but they also form a unique natural laboratory in which we can study ways to reduce that risk. In this laboratory, the Earth is performing an experiment that, if we are able to observe it closely, will teach us much about plate tectonics and its relation to earthquake hazard. Recognizing this, our discussion at the workshop led to four major research objectives and clarified the need for new surveys to meet these objectives.
Our first major objective is derived from the research results of many of our colleagues. The North Anatolian Fault System is an evolving plate boundary system. This means that it is changing over time and that tectonic models need to account for this temporal evolution. The major implication of this result is that the stress changes that cause earthquakes can shift as the boundary evolves. Thus our first objective is to update existing tectonic models to include time evolution. It is also clear that effective models must be three-dimensional.
Our second major objective is to update the maps of active faults, and to identify and characterize structures in the crust that may have caused earthquakes in the past. We must measure rates and directions of slip along these faults, and rates of deformation generally in the crust.
Our third major objective is to understand the nature of the major bends in the North Anatolian Fault System, and the nature of the system's western termination against the Greek mainland. These features are in regions where the background plate tectonic stress is being reoriented, which may lead to important stress concentrations in certain areas.
Our final major objective is to show how our new understanding can be made useful for assessing earthquake hazards. We want to try to close the gap between science and its application to protect people from earthquakes.
To achieve these objectives, we will need new observations of the active and inactive faults in the region and of other geological structures. Most of the North Anatolian Fault System is submerged beneath the Northern Aegean and Marmara Seas, so new observations can only be obtained by coordinated marine surveys of the seafloor. There should be a special emphasis on detailed maps of the seafloor in critical areas. In addition, new technologies should be used to image the shallow sediments, which will give us important information on the recent history of fault movement, including the resolution of ruptures from past earthquakes.
Images of the seafloor and below will provide guidance for obtaining sediment cores, a second component of the survey. Sediment cores can be used to obtain precise timing for past events, in order to provide constraints on the rates of crustal deformation and movement. It is inefficient to take cores at random sites, so it is important to have detailed seafloor maps and sediment images so that the best coring sites can be selected.
The seafloor maps, the sediment images, and the cores will together form the most complete set of submarine geological information ever assembled for the Northern Aegean and Marmara Seas. These surveys will contribute significantly to the resolution of the scientific issues.
In addition to the marine surveys, it will be important to measure the locations of earthquakes as accurately as possible. Both Greece and Turkey maintain earthquake-monitoring systems that serve the purposes for which they were designed. But new technology can be applied to supplement these networks in regions where there might not be enough coverage. Portable seismographic stations can be deployed both on land and underwater to provide enhanced capability for locating earthquakes. New location techniques have been deployed which could use the combined earthquake observations to map out active faults with unprecedented precision. When combined with the seafloor maps, we may be able to understand the relationships between present-day active faults and past deformation. We will also gain new insights on how stress is transferred between fault segments and branches throughout the region. As the technology develops, some of the temporary underwater deployments could be converted into permanent underwater observatories that could relay earthquake information continuously.
Finally, it will be important to compare the results of the marine surveys and earthquake analysis with new on-land investigations, particularly for understanding deformation across continental Greece, as well as in circum-Marmara region near Istanbul. Thus we are proposing a new set of on-land geological investigations that will complement the marine survey.
These initial surveys can provide the baseline against which other surveys and observational techniques can be assessed. We will coordinate our studies with ongoing work in related fields such as remote sensing and satellite geodesy.
These new surveys and observations will produce much new data useful for research collaborations. Significant progress in developing hazard mitigation and risk reduction policies requires that scientific consensus be effectively communicated to the authorities and decision-makers. This communication has to go beyond the normal publication of scientific results and must be matched to the requirements of decision-makers.
Thus we suggest the establishment of an Internet-based Northern Aegean and Marmara Earthquake Information Network. This Information Network should have links with existing regional and local data management efforts. It could also serve as an electronic village for international research collaborations and could be the basis for building knowledge integration tools for earthquake hazard reduction. It would be a useful tool in making earthquake science more relevant to the local, regional, national, and international decision-makers who must help to mitigate the hazard and reduce the risk, and who will make improvements in emergency response.
We are committed to open science collaborations and shared data policies. We believe that such a philosophy can be reconciled with the normal demands of scientific publication and data ownership.
We have outlined today, very briefly, some of the results of our three-day discussions in Thessaloniki. As we have stated, this is just the beginning of a process that we hope will result in an international scientific program focused on the Northern Aegean and the Marmara. At our next meeting in Istanbul, we will begin a much more detailed study of the outstanding research issues and will continue to make plans for the surveys that will be needed to address them.
Thank you for your attention.
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