Here’s an example of a magnitude 7.0 earthquake in Anchorage disrupting a synchronome clock near Seattle - http://leapsecond.com/pend/synchronome/quake.htm
(Not a fancy Shortt-Synchronome tho)
Wow interesting. I would have bet (and lost) that the seismic activity would have been at a such higher frequency that it wouldn’t have affected the 1Hz pendulum. I suppose either that is wrong or there’s also some much lower frequency energy in an earthquake.