Why are there giant concrete tunnels in the desert?

Dear Diana, I have a question about LIGO that I hope you can answer. A few years ago I was loosely involved with laser interferometers to measure mechanical vibrations of musical instruments like the violin. As far as I remember, the wavelength of the laser determines the vibration amplitude that you can measure (shorter wavelengths can measure smaller amplitudes). In another video I saw however, that the LIGO laser is an infrared laser, ie it's wavelenght is longer than that of visible light. How can it then measure such small vibrations? Would it not have to have smaller wavelength to be able to measure such tiny vibrations? Thanks for your channel, my kids and I watch it all the time.