Underground laboratories and deep underground geophysical observations

Characterized by lower background condition, underground laboratories provide important experimental space for many frontier researches and have become national key scientific research platforms in many countries. At present many countries in the world have established underground laboratories by using cavities in mountains or underground mining tunnel. Most of them are mainly for astrophysics and particle physics experiments, and few of them are aimed at geoscience, rock mechanics, dark ecology, etc. Based on the introduction of some important underground laboratories in the world, this paper focuses on observations and experiments in geophysics. And then the measurement indices of multi-physical fields that can be achieved by observing in "ultra-silent" and "ultra-clean" deep underground environment are emphasized. Aiming at ultra-high precision observations that can be realized in deep underground, this paper also discusses the challenges posed by deep geophysical observation to current instrument science, equipment and observation technology, and imply a series of key basic scientific problems on geophysics faced by deep underground observation.