Mont Terri

Mont Terri is a hill in the Jura Mountains in the Canton of Jura, Switzerland, notable as the location of an underground rock laboratory. The site hosts research dedicated to the properties of claystone and to questions around geological isolation of radioactive materials.

The main feature is the Mont Terri Rock Laboratory, an excavated facility with galleries and instrumentation where international teams run experiments on hydrogeology, geochemistry and rock mechanics. The facility is used for long-term experiments rather than general tourism, and it supports scientific collaboration on disposal concepts and engineered barriers.

The rock laboratory was developed to provide an in-situ research environment for studying the behaviour of clay formations under repository-relevant conditions. Over time it has become a reference site for experimental work on clay host rocks and underground research infrastructure.

Mont Terri sits in the Jura range near the France-Switzerland border in the Canton of Jura, occupying a geological setting typical of folded Jura terrain and clay-rich formations.

• Research focus: The site focuses on experiments in Opalinus Clay and related rock mechanics that are relevant to the long-term geological disposal of radioactive waste.
• Limited public access: Access to the underground laboratory is primarily for research personnel and organized visits; the facility supports international collaborative experiments.

What to See #

• Mont Terri Rock Laboratory: An underground experimental facility excavated in the local rock, used by international research teams to study claystone behaviour, hydrogeology and engineered-barrier interactions.