I reported suspisions about the ETF (Stanford) Seismometer that is now wired up as the STS2-A or HAM2 ground sensor.  That was ten days ago and here is another look from earlier this morning.  Pretty much same conclusion:  The ITMY and HAM5 units show very good coherence even though they are separated by 30meters.  The HAM2 & ITMY sensors are just a couple meters apart and they are no showing the coherence they should: and the HAM2 & HAM5 sensors coherence is similarly poor..

While the problem may be cable or setup (level or igloo rubbing) I suspect the unit itself.

BTL: Any word on these instruments from your experiences?