Fifty years ago, the theory of plate tectonics revolutionized geology. This new conceptual framework made it possible to understand continents and oceans’ formation and the distribution of volcanoes and mountains. Plate tectonics is a model that describes the movement of the cold, rigid layer that forms the Earth’s surface, the lithosphere.
In the 1960s, scientists used paleomagnetic and geophysical measurements to resolve past movements from the ocean floor’s age and thus discovered that the rocks that make up the planet’s surface had moved.
But it was not until the 1980s that geodetic measurements and artificial satellites and radio telescopes were used to determine this movement’s current speed.
Such precise measurements were recorded at a minimal number of points on the surface where GPS stations or large astronomical observatories existed.
The improvement in describing the movements of the Earth’s surface has been progressive but slow.
These measurements have improved, allowing us to improve our maps’ accuracy and make navigation more reliable.
However, although there are countries with large measurement infrastructures and dense networks of GPS stations, it has not been possible to observe and characterize these movements in detail. Also, with high spatial resolution due to the immense surface of the Earth.
High-resolution movement
Since the late 1990s, radar-satellite interferometry has enabled researchers to capture ground movement maps with high spatial resolution. However, the limited availability of these satellites prevented this technology from being used to generate continuous maps.
This changed at the end of 2014. Since then, the Sentinel-1 satellites of the Space Agency and the European Commission allow high-resolution global observation of the crust movement with their interferometric radar sensors (InSAR). Also, the information collected by this mission has an open data policy, which makes it a valuable resource for research.
The project’s research team has used a supercomputer in the UK that stores a copy of all the mission data. Through millions of hours of computation, thousands of radar images have been processed. Thus, researchers have managed to obtain the first map of the surface of a complete tectonic plate, the Anatolian plate in Turkey.
Measurements of surface deformation are essential for the evaluation of seismic hazard in the medium and long term. Although it should be remembered that at present, the prediction of earthquakes is not possible, advances such as the one represented by this study bring us a little closer to that objective.
Researchers have developed new automated InSAR image processing systems and exploited the first five years of Sentinel-1 data. With this, it has been possible to measure surface movements for the region of Anatolia, of approximately 800,000 km².
The new 3D and horizontal warp rate maps show the warp patterns, which are dominated by the westward movement of Anatolia relative to the Eurasian continent.
The accumulation of deformation is located along the large tectonic faults situated to the north and east of the Anatolian plate. Simultaneously, the vertical signals are fast and are associated with anthropogenic activities such as the extraction of groundwater. To a lesser extent, the vertical component also captures the tectonic extension that is associated with the longitudinal valleys (grabens) of western Anatolia.
This research demonstrates that the use of satellite data from the Sentinel-1 mission, coupled with automated InSAR processing, can allow the development of a highly detailed characterization of velocity fields with high resolution. Also precision, in large regions of the continents. These results are important to evaluate, among other geological phenomena, the relationship between the rate of accumulation and release of pressures in the rocks of the earth’s crust associated with earthquakes.
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