Joe Frisch visited the EXPO 2001 SENSOR in Philadelphia, with the purpose to determine whether we can find commercially available compact seismometers suitable for final doublet stabilization. Conclusion is that no one makes exactly what we need, confirming the need for custom design (built in house or externally). See details in Joe's summary.
Andrei reported about the trip he and Fred Asiri made to the NLC site 135 (cut and cover site). Results of seismic background noise measurements (on surface) were shown. The background noise was found to be slightly higher than at the site 127 (see report here). Absence of any cultural noise is what presently makes it quiet.