Hi Don,

That's an interesting link. Those experiments look like fun, but constructing equipment like that is beyond both my budget and skill to understand the instructions & diagrams.

I don't know how seismographs could show whether heavy traffic affects earthquakes unless a 'control' area without heavy traffic is studied during the same time period. Then if the remote area consistently has fewer earthquakes on the same days that S.F. and L.A. have fewer quakes, a researcher could assume traffic didn't cause the increased number of quakes in high traffic areas. But that still wouldn't show what DID cause them.

Mary C.