EUROPEAN EARTHQUAKE PROJECTS Understanding the furies of the Earth
European earthquake research is active on many fronts: improved seismic shock scenarios, the analysis of past earthquakes, the study of so-called ‘dormant’ zones, the deployment of measurement and observation infrastructures, improvements to tools and methodologies, international and intercontinental co-operation.
Palaeohistory returns with a vengeance
Example of a palaeoseismic site: the Guzelkoi region in northern Anatolia, scene of a 1912 earthquake.
Five years ago and in the space of just three months (17 August and 12 November 1999), western Turkey was hit by two major earthquakes, with a magnitude of 7.4 (epicentre near the city of Izmit) and 7.1 (Sea of Marmara) respectively. The toll was 30 000 dead, more than 50 000 injured, and material damage estimated at over €35 billion. As occurs after every major earthquake, many research projects and field studies were subsequently carried out, focusing on the regions of Anatolia through which the Izmit Ducze and Marmara faults run – faults that now seem to be dangerously active at the boundary of the Eurasian and African plates. “Such a sequence of two earthquakes so close together in time and place is unique in the recent past,” stresses Mustapha Mehgraoui of the Institut de Physique du Globe in Strasbourg (FR), who coordinates the EU-backed project Relief (Reliable information on earthquake faulting). "In any event, it has demonstrated the inappropriateness of seismic risk scenarios established on the basis of standard probabilistic assessments that are simply based on seismic history and simplified seismotectonic sources.”
The Relief project, launched in 2002, is engaged in a vast exercise to study the geophysical terrain along the long line of these two faults – and in particular the 170 km rupture line caused by the 1999 earthquakes – by means of field tests and aerial or satellite pictures. "One of the specific originalities of our approach is the inclusion of a much more retrospective methodology to the region’s seismic history, one going back well before the earthquake registering 7.4 that hit the Sea of Marmara in 1912. The Earth operates on a time scale that is incommensurate with our own. Many geophysicists are convinced that palaeoseismology, that is the search for traces left in upper geological layers by earthquakes dating back to the Holocene or Late Pleistocene periods – about 20 000 years ago – are a rich source for understanding the present risks presented by active faults.”
A deceptive calm in Western Europe? If we exclude its southern section running from Greece to Italy through the Balkans, Europe has low seismicity – at least for now. But is this relative calm deceptive? Some zones that experienced violent earthquakes in the past must be viewed as potentially active. Specific examples are Provence and the Rhône valley, the Rhine valley and Pô Plain, the Catalan coast and southern Spain. Although the risk is currently considered to be low, or unknown, Western Europe’s potential vulnerability is, by contrast, high, due to its high population and infrastructure density, coupled with the rare application of paraseismic standards, owing to the absence of earthquakes in recent memory.
Many in-depth geomorphological and geological studies today provide us with quite a well-documented knowledge of relatively inactive faults. But the intensity of plant cover and the major and permanent changes to the landscape due to human activities are obstacles to observation of the slow deformations linked to the action of faults. Between 2001 and 2004, the SAFE project undertook an in-depth updating of this misleading impression of security. Using the most advanced seismological approaches, the project produced a new mapping of seismic risks in certain zones and set up expert systems to help establish new diagnostics for assessing potential risks.
Left: Study trench in Guzelkoi. Right: In this fault zone, the black arrows show the scars of faults dating back to 1912.
Euro-Mediterranean seismology in the virtual age The seismological destiny of the two sides of the Mediterranean is inextricably linked to the interaction between the Eurasian and African plates. It is on the basis of this major tectonic boundary that Europe has developed a powerful system of detection, in co-operation with its partners on the other side of the Mediterranean, from Turkey to Morocco. The deployment of this measurement infrastructure (over 2 000 seismographs, as well as the accelerometers and other provisional sensors linked to more than 100 specialised observatories) has been particularly intense over the past decade, rendering the Euro-Mediterranean network comparable to the monitoring systems found in California or Japan.
But how should we go about managing such a massive stream of data provided by so many different players? The first step, in 1975, was to set up the Euro-Mediterranean Seismic Centre (CSEM-EMSC), under the auspices of the European Seismological Commission, whose principal mission is to centralise information and data and convey warning messages – in particular to the Council of Europe and other European institutions.
In the 1980s, the appearance of new very high-performance seismometers based on broadband digital technologies led to the creation of the Orfeus (Observatories and Research Facilities for European Seismology) network that is dedicated to the development of these tools, as well as data transmission and processing software.
However, over the past decade the rapid increase in the use of information and communications technologies via the Internet has come to pose a continuous challenge to the Euro-Mediterranean seismological infrastructure. “There is a need to unify standards, protocols and exchange procedures and to ensure total software compatibility. If not, we are going to be faced with an increasingly problematic diversity,” explains Torild van Eck of the Royal Netherlands Meteorological Institute (KNMI), the headquarters of the Orfeus network. "In 2000, as part of European support for research infrastructure under the Fifth Framework Programme, we received financing to launch the Meredian (Mediterranean-European rapid earthquake data information and archiving network) project. The aim was to put into place the tools to optimise exchange, archiving and access for the vast quantity of data collected by some 400 stations equipped with broadband digital systems within the Orfeus network.”
One of the most valued achievements of the Meredian project is the VEBSN (Virtual European scale broadband seismograph network), a high performance Internet platform for the real time exchange, updating and consultation of digital data obtained from a vast network of over 100 seismological stations. As soon as an event occurs – as happened, for example, at the time of the earthquakes in Algeria in 2003 and in Morocco in 2004 – users are able to obtain valuable information in record time on the situation in the affected areas, the amplitude of surface waves, the shocks recorded, the sequence of aftershocks, etc.
This increasing integration of Euro-Mediterranean observation networks is destined to spread, as it grows to include more of the new or candidate EU Member States and the high seismic risk area of the Balkans.
Natural disasters – landslides, avalanches, floods, earthquakes, volcanic eruptions,etc. – are many and varied, and a wide range of European research projects are engaged in either preventing them or mitigating their effects. “It is important not to have rigid compartmentalisation ...
Testing resistance, training researchers
In the field of research on paraseismic technologies, the Union plays an active role in promoting access to test infrastructures and training researchers. Ecoleader(1) is a consortium of the European Laboratory for Structural Assessment (ELSA) – the part of the Joint Research ...
Natural disasters – landslides, avalanches, floods, earthquakes, volcanic eruptions,etc. – are many and varied, and a wide range of European research projects are engaged in either preventing them or mitigating their effects. “It is important not to have rigid compartmentalisation between the various earth science disciplines that are working on these subjects,” explains Denis Peter, a scientific officer at the European Commission. The EU-MEDIN platform is an information tool that seeks to highlight current research projects, the approaches and methodologies used, and any significant results. At a future date, it will also seek to highlight European activities or initiatives (European civil protection, Interreg regional projects, etc.) that help reduce risk and/or increase risk awareness. “We must build bridges between research and applications so as to improve synergy and interaction between the knowledge and know-how that is being built up on all these fronts.”
In the field of research on paraseismic technologies, the Union plays an active role in promoting access to test infrastructures and training researchers. Ecoleader(1) is a consortium of the European Laboratory for Structural Assessment (ELSA) – the part of the Joint Research Centre in Ispra (IT) which tests the resistance of construction structures – and five other research centres in the Member States that specialise in simulating the characteristic vibrations of seismic waves(2). Consisting of a Reaction Wall fitted with hydraulic jacks, the equipment at the ELSA laboratory is unique in Europe. Life-size construction prototypes are subject to extremely slow and very high-density shocks, which are controlled and calculated electronically, permitting a detailed analysis of the deformation of materials and structures.
The SAFERR(3) thematic network provides young European or foreign researchers with advanced training in fields related to the prevention or mitigation of seismic hazard and paraseismic devices.
(1) European consortium of laboratories for earthquake and dynamic experimental research. (2) Universities of Bristol (EERC, UK) and Athens (NTUA, EL), LNEC (PO), Enel.Hydro (ISMES, IT) and CEA/Saclay (FR). (3) Safety assessment for earthquake risk reduction – Network set up under the 'Human Potential' programme.