Characterization of Gravity Gradient Noise at LIGO (Laser Interferometer Gravitational Wave Observatory), Livingston, LA

The researchers wish to characterize the gravity gradient seismic noise at the LIGO Livingston Observatory (LLO). LIGO (Laser Interferometer Gravitational Wave Observatory) consists of two almost identical large scale land-based Michelson type interferometers sponsored by the NSF. One of these, the LLO, is located in Livingston, LA and the other is at Hanford, WA. This will be a continuation of work begun last summer. During last summer we concentrated on measuring the relative microseismic noise between pairs of guralp 3esp sensors separated by distances of 4 km. Most of the measurements were performed inside buildings. About 2-3 weeks were also spent on preliminary gravity gradient noise measurements with typical separations of 5-30 meter. The researchers would like to continue the gravity gradient noise characterization (in the range 1-30 hz1) with an array of guralp 40 T's.