Abstract
A 30 m laser strainmeter is currently being operated in an unworked gold mine near Boulder, Colorado. The strainmeter consists of an evacuated Fabry-Perot interferometer illuminated by a 3.39 pm He-Ne laser. A second 3.39 pm laser is stabilized by means of saturated absorption in methane and its wavelength serves as the reference length for the system. We shall describe the instrument in some detail and present the latest results in our investigation of the Earth tides and the Earth normal modes.

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