https://earthquake.usgs.gov/data/dyfi/ USGS' "Did you Feel it Program" helps USGS figure out how seismic waves travel through the crust, which isn't uniform in density. Useful beyond seismographs.

Sure, they have seismographs, but they don't necessarily have full details on all the subsurface geology between you and the epicenter. Wave propagation can be complicated... depending on what's down there, the waves can intensified, dissipated, reflected...

If (e.g.) everyone in a small area reports strong shaking, while those in surrounding areas report less, that can indicate a need for further investigation as to whether the area that experienced strong shaking poses a specific risk.

> Does human reporting add resolution or other information to their data?

Yes, a lot. They only have so many seismographs. They ask a bunch of survey questions that get them a pretty good qualitative score of the experience in your exact location, and when merged together gives them a much better picture of how the waves propagated.

Also they ask you questions about damage, which they can't get from anywhere else.

With a standardized report format the data can complement modelling of ground motion intensity caused by an earthquake, such as https://earthquake.usgs.gov/data/shakemap/