In Turkey, the sequence of major earthquakes shows a clear progression to the west along the North Anatolian Fault. Researchers' attention is particularly focused on the area under the Sea of Marmara, which has remained silent for more than two and a half centuries, a period of calm that suggests a significant accumulation of tension.
An international team, led by scientists from Japan and Turkey, recently published in
Geology the first complete three-dimensional model of the subsurface in this region. This achievement offers a much finer understanding of the fault's structure.
Istanbul, the capital of Turkey, borders the Sea of Marmara.
Image Wikimedia
To develop this model, scientists used a technique based on magnetotelluric measurements. With more than twenty stations, they recorded subtle changes in the Earth's natural electric and magnetic fields. These data allow measuring the electrical properties of rocks up to several tens of kilometers (dozens of miles) deep. This indirect measurement is a valuable tool for probing the subsurface without resorting to drilling, a major advantage for marine studies.
The examination of collected information revealed a detailed arrangement of zones with different electrical resistivity. Regions with low resistivity, often associated with the presence of water or fluids, are mechanically less strong. Conversely, zones with high resistivity appear more rigid and locked, likely accumulating more tension. The scientific team hypothesizes that the next major earthquakes could originate at the boundaries between these sections with opposite characteristics.
These observations have immediate consequences for the assessment of seismic risk in the Istanbul region. By providing clues about the location and possible magnitude of future events, this model allows for preparing disaster preparedness strategies.
Located in an active tectonic zone where several plates meet, Turkey has a seismic history marked by major events and disasters. This study is part of a long series of research, but it stands out for its remarkable precision. Ultimately, similar work could be conducted on other major faults.