The Mont Terri Rock Laboratory near Saint-Ursanne
15 December 2025
Switzerland is known for its excellent research institutes, scientific research and universities. The topics and themes range from climate change, glaciers, medicine and pharma, and CO2 reduction to technologies and other fields. The country is one of the world’s champions of innovation and patents. They have one thing in common: they occur at or above the Earth’s surface.
The Collégiale of Saint-Ursanne
Who would have thought that more than fourteen hundred years after the arrival of Saint-Ursanne, one of the most advanced research projects would be taking place three hundred metres underground near the monastery?
However, 300 metres below the earth’s surface, close to Saint-Ursanne (Canton Jura), is an innovative research project. The Mont Terri Rock Laboratory celebrated its 25th birthday in 2021. What began in 1996 as a small research facility in the Opalinus Clay of the Mont Terri motorway tunnel is now an internationally renowned research laboratory.
The Mont Terri visitor centre provides a well-documented overview of the kilometres of underground passages and the many fascinating experiments carried out at a depth of 300 metres for almost 25 years. There are also guided tours of the ‘laboratory’ for groups of at least ten people.
The railway station of Saint-Ursanne (canton of Jura) is located on the mountain near the Mont Terri underground laboratory project (Laboratoire souterrain Mont Terri/Felslabor Mont Terri. This unique international and intergovernmental project, initiated and supervised by swisstopo (a body of the Swiss Federation), has existed for several decades.
The monastery’s first known abbot (Bourquard of Burco, 1119-1139) and the last (Jean-Jacques Keller, 1789-1793) would have been proud.
The abbot from 1119 tot 1793
Opalinus Clay
The Opalinus clay was formed in the Jurassic period, some 180 million years ago. A subtropical sea then covered the region. The underground water still contains salt for this reason. The clay is almost impervious, making it an interesting material for storing radioactive materials and CO2.
The last 25 years have demonstrated that claystones, such as the Opalinus Clay, can safely contain radioactive waste over extremely long periods. Claystones and mudstones serve as a confinement function, also preventing gases such as CO2 from penetrating the biosphere from deeper layers.
The website provides an excellent overview of the history of the past 25 years, the development of the Mont Terri rock laboratory, the experiments and their results, and an outlook on future research priorities.
The Mont Terri Rock Laboratory has a total length of 1,280 meters. It began in 1996 with small niches and continued to expand until 2018.
Organisation
More than 500 people from 22 partner organisations, including governments, universities, and research institutes, from Europe, Japan, Canada, and the United States. Two petroleum companies are also involved.
The Project has three main objectives: to research and develop new methods that can be applied in claystone such as the Opalinus Clay, but which are also transferable to other argillaceous formations worldwide, to characterise the Opalinus Clay, which means to acquire knowledge of the physical, chemical and biological properties of this clay formation, and to carry out demonstration experiments. Young scientists from around the world contribute to numerous experiments.
The latter primarily demonstrates the long-term behaviour (hundreds of thousands of years) and the feasibility of constructing a disposal system. The main question is always the same, whether for radioactive waste or CO2 storage: is a deep repository system safe, in that it does not threaten the operators in the short term and the geosphere and the biosphere in the long run?
Legal basis and funding
The legal basis between the research partners and the Swiss operator Swisstopo defines the rights and obligations of the Project Partners. The Swiss Federal Office of Topography swisstopo is the geo-information centre of the Swiss Confederation.
Since 2010, Swisstopo has operated the Mont Terri Visitor Centre in collaboration with NAGRA (National Cooperation for the Disposal of Radioactive Waste/Nationale Genossenschaft für die Lagerung radioaktiver Abfälle) and ENSI (Swiss Federal Nuclear Safety Inspectorate/Eidgenössisches Nuklearsicherheitsinspektorat).
As the facility owner, the Canton of Jura supervises the operator SWISSTOPO and grants it annual authorisation to conduct the experiments. The Canton of Jura has established a monitoring commission, known as the Commission de suivi.
To date, around 180 experiments have been performed in the rock laboratory. Of these, 75% have been completed, analysed and published. Currently, approximately 45 experiments are running. The Swiss government covers around 40% of the budget.
To illustrate the subtropical sea from 175 million years ago, the project also offers many fossils and geological strata from that period and later.
Research and experiments
The research and development sector is concerned with matters of testing and further development of investigative technologies, e.g. drilling and excavating technologies, continual sampling of pore water, geochemical and microbiological experiments, earthquakes, ascertaining ground pressure, development of suitable hydro-tests in highly impermeable formations, measurement of geological changes in host rock and pore water in a deep storage system, methodologies for long-term monitoring.
Future
The Project is a so-called rock laboratory. It means that it is used exclusively for research. There will never be a deep geological repository. A key feature is that partners can choose their research priorities. The central theme will remain a repository for the long-term storage of radioactive waste. However, the laboratory will also increasingly make an essential contribution to energy strategies and CO2 reduction experiments.
(Source and further information: www.mont-terri.ch).