I can believe it - I’ve watched the seismograph at Berkeley, which is about 3 miles from the I-80 corridor (one of the ten busiest highways in the US), and there was always a background vibration recorded that the techs said was from the freeway traffic.
@unksol for you and me, nothing. For those who study this stuff, it gives them an opportunity. Kind of establishes a better baseline or creates a control group, they can then use in scientific studies to compare “findings” for degree of effect. I understand after 9/11 those who study the sky (jet stream/air movement/contrails impacts) had a similar opportunity. Probably not perfect (grocery store trucks still are moving) but a good data point.
@unksol agreed, I was reading your response literally/thought others might find it interesting why scientists want even the human noise out of their baseline. Minute noise, and even still there now, but it does have an effect. More because the equipment sensitivity than the noise’s real effect.