To address these issues, Terrafirma is providing a Pan-European ground motion hazard information service to detect and monitor ground movements in relation to building stability, subsidence and ground heave, landslides, seismic activity and engineered excavations.
For over 15 years, Synthetic Aperture Radar Interferometry (InSAR) has been providing ground deformation data at centimetre precision. In the past five years, however, new ways of processing satellite radar images have been developed using Persistent Scatterer Interferometry (PSI) that allow ground movements over wide areas to be detected and monitored with even greater sensitivity.
Recent statistics show that 50% of the world population already live in cities, and megacities (over 10 million) are now commonplace. As the trend toward urbanisation continues, most major towns will undergo construction to accommodate new developments for newcomers.
New construction requires solid foundations to avoid costly planning mistakes, and underground works and metro-tunnelling have some surface effect that needs remediation and monitoring. The Terrafirma services can provide information to locate low-risk foundation sites and help save money on the remediation of existing structures.
Land movement in the form of earthquakes and landslides poses a threat to large populations around the world. Within the Terrafirma project some focus has been placed on cities which have a long history of seismic activity, such as Istanbul, Turkey.
Turkey’s location has made it vulnerable to earthquakes with the 1000-kilometre-long Northern Anatolian fault located just 15 kilometres south of Istanbul. It is also located on the relatively small Anatolian plate, which is squeezed between three other major tectonic plates – the African and Arabian plates to the south, and the Eurasian plate to the north. The combination of these plate movements has been the source of eight earthquakes of magnitude 7 or greater in the last century.
The 1999 earthquake in Izmit, about 80 kilometres east-southeast of Istanbul, had a magnitude of 7.6, initiating efforts to assess the risk in urban areas. The new PSI studies have yielded a subsidence map giving first-hand evidence of the high degree of spatial variability of the ground conditions throughout Istanbul’s urban area, and have contributed to a re-definition of their seismic risk maps.
Another urban area being studied for earthquake risk within the Terrafirma project is Lisbon, Portugal, where devastating earthquakes have occurred. The unique information being provided by InSAR in these and other areas is causing seismologists to re-evaluate their data to incorporate new information and refine their estimates of the likely repeat cycles for earthquakes and the future possible epicentre locations. The sophistication of the refinements is likely to lead to a widespread requirement for InSAR data across all areas of seismic risk.
Landslides are another type of ground movement which cause enormous economic losses and claim thousands of lives every year. The cost due to landslides in Italy is estimated to be between €1 and 2 billion annually over the last century, and they have resulted in an average of 60 deaths per year. Terrafirma is examining landslide sites, with the PSI information going to the national geoscience centres and engineers for expert interpretation using their own data and expertise.
Terrafirma monitored the Cutigliano village in Italy’s Tuscan Apennines for landslide risks. The use of PSI allowed the identification of more than 200 measurements along the village’s slope. By combining InSAR measurements with ancillary data such as aerial photos and topographic and geomorphologic maps, Terrafirma was able to provide an accurate analysis of the landslide's spatial distribution and state of activity and identify unknown unstable areas.
Within two years, Terrafirma, which was initiated by Nigel Press Associates under ESA’s GMES Service Element Programme, will provide satellite radar coverage processed to reveal small ground movements for at least one city in every European Union country.
Mariangela D'Acunto | alfa
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy