Switzerland coordinates an extensive network of 600 seismographs stretching from Perpignan to Prague. The data obtained will enable better estimates of earthquake risk in Alpine regions.
Buried in a meadow, hidden in a barn and anchored at the bottom of the Mediterranean: 600 sensors placed on and around the Alps constitute the largest academic seismographic network in the world. The AlpArray project will enable better understanding of the birth of the Alps as well as homogeneous seismic hazard maps of the Alpine regions. Comprising 36 institutions from 11 countries, the project is coordinated by scientists at ETH Zurich and the University of Lausanne and is supported by the Swiss National Science Foundation (SNSF).
"We use extremely sensitive stations", explains György Hetényi, SNSF Professor at the University of Lausanne and first author on the publication detailing the implementation of the network.(*) "The stations can detect a mild earthquake in Japan, as well as thousands of seismic events that occur each year in Switzerland, 99% of which the population is unaware of."
The primary aim of the project is to better understand the structure and composition of the lithosphere (up to a hundred kilometres under the Alps) as well as the earth's upper mantle (up to 660 kilometres). It is at these depths that the traces of ancient ocean floors which are tens of millions of years old can be found. Tectonic movements continue at the surface and produce present-day earthquakes in Alpine regions, explains Hetényi. The collected data make it possible to compare and standardise the catalogues of events maintained by European countries, and thus to refine probability estimates for earthquakes.
Two thousand metres under the sea
Half of the network consists of existing stationary seismographs. The other half comprises mobile sensors, distributed during the two years of the project and placed both underground and in barns in high mountain pastures. "Convincing our partners to make so many stations available at the same time was not easy, but it's the only way to create this network and still keep costs under control. Only four countries had to buy new sensors."
Launched by Switzerland, AlpArray is managed by Edi Kissling and Irene Molinari of ETH Zurich, John Clinton of the Swiss Seismological Service and György Hetényi of the University of Lausanne. The Swiss part of the project is supported by a Sinergia grant from the SNSF.
The sensors were placed in a hexagonal network, analogous to the cellular structure of a beehive. "It was the most efficient way to achieve a dense geometry considering the fixed stations", explains Hetényi. "No part of the studied region is more than 30 kilometres away from a sensor." AlpArray extends more than 200 kilometres around the Alps, from the Pyrenees to Hungary and from Frankfurt to Corsica. Thirty sensors were installed at the bottom of the Mediterranean Sea. "It was only after fishing them back out last February that we got confirmation that they had worked properly, because the water column above them prevents wireless transmission", says Hetényi. The deepest station is 2771 metres under the sea; the highest is at an altitude of 3005 metres.
An "ultrasound" of the Alps
Mapping the Alpine structure is akin to doing an ultrasound: the sensors record the echo of seismic waves reflecting off the deep layers of the Earth. Comparing the arrival times of the waves at different sensors enables the researchers to triangulate the position of the layer as well as its composition, since the latter affects the propagation speed of the waves.
The recorded shocks come from small seismic events in Europe and moderate earthquakes all over the Earth. The network can even use ambient noise, such as from the swell of the sea, to obtain information about geological structures near the surface, down to a depth of a few tens of kilometres.
The AlpArray network has been fully operational since July 2017. Initial results are expected in 2019.
The stations of the AlpArray Seismic Network field experiment are collaboratively operated by the following institutions (alphabetical order): (alphabetical order): Czech Academy of Sciences, Deutsches GeoForschungsZentrum, Freie Universität Berlin, Geozentrum Hannover, Goethe University Frankfurt, Helmholtz Centre for Ocean Research Kiel, Hungarian Academy of Sciences, Istituto Nazionale di Geofisica e Vulcanologia, Istituto Nazionale Di Oceanografia E Di Geofisica Sperimentale, Karlsruhe Institute of Technology, Kövesligethy Radó Seismological Observatory, Ludwig-Maximilians-Universität München, Observatoire de la Côte d'Azur, Republic Hydrometeorological Service of Republika Srpska, Ruhr-University Bochum, Slovenian Environment Agency, Swiss Seismological Service at ETH Zurich, Università degli Studi di Genova, Universität Kiel, Université de Strasbourg, Université Paris Diderot, University Grenoble Alpes, University of Leipzig, University of Potsdam, University of Vienna, University of Zagreb, Westfälische Wilhelms-Universität Münster, Zentralanstalt für Meteorologie und Geodynamik.
In addition to the SNSF, the research was financed by the following institutions (alphabetical order by country: FWF (Austria); HRZZ (Croatia); Czech Academy of Sciences and CzechGeo/EPOS (Czech Republic); ADEME, ANR, Labex OSUG@2020 and RESIF (France); DFG (Germany); Development and Innovation Fund and Hungarian Academy of Sciences (Hungary); INGV (Italy).
G. Hetényi, I. Molinari, J. Clinton et al.: The AlpArray Seismic Network: a large-scale European experiment to image the Alpine orogeny. Surveys in Geophysics (2018) doi: 10.1007/s10712-018-9472-4 (Open Access)
Prof. György Hetényi
Faculty of Geosciences and Environment
University of Lausanne
Phone: + 41 21 692 43 21
https://link.springer.com/article/10.1007%2Fs10712-018-9472-4 'The AlpArray Seismic Network: a large-scale European experiment to image the Alpine orogeny.'
https://flic.kr/s/aHsmaJ27B1 'Pictures for editorial use'
http://p3.snf.ch/project-157627 'SNSF project OROG3NY'
http://p3.snf.ch/Project-154434 'SNSF project SWISS-AlpArray'
Medien - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft
Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen
The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences