Deep Underground Gravity Lab

This award will support operation of an underground seismometer array in the Homestake mine in South Dakota. The array currently includes eight seismic stations, probing the available depth and vast horizontal extent of the mine, each operating one high-sensitivity broadband seismometer. The award will support a graduate student who will, with supervision by the PI and collaborators, perform the necessary upgrades and maintenance of the array, as well as ensure acquisition of data by the array over the two-year project period. The student will also conduct several data analysis projects, including first studies of the underground seismic noise, studies of the local seismicity, and effects of the surface on the seismic field content and propagation.

The unique data provided by this array will reveal important characteristics of the seismic motion underground such as its amplitude, modal content, and effects of rock non-uniformity. Good understanding of underground seismic motion will be crucial for the development of motion-sensitive experiments in physics, such as gravitational wave detectors or tests of the equivalence principle that underlies Einstein's theory of general relativity. Due to a very strong interest in this data among the geophysics and seismology communities, the data will be made available to these communities via the 'Incorporated Research Institutions for Seismology' (IRIS) program. The data will also be made available to high-school students in the Twin Cities area through the 'Interactions In Understanding the Universe' (I2U2) program, exposing them to the real data with all its subtleties and imperfections, and to the large computing resources that are used to solve some of the most complicated scientific problems today.