If you look at the Richter scale a magnitude of 4.0–4.9 is considered Light with noticeable shaking of indoor items, rattling noises. Significant damage is unlikely. A 3.0–3.9 is Generally not felt, So we have plenty of people on the scene reporting significant ground shaking, ratting noises that sort of thing even though the recordings don't show that. 4.0 on the Richter scale would be the equivalent to a 1kt nuclear blast, although with decoupling from the ground the vibrations can be reduced from the 1 kt blast to the equivalent of a magnitude 2.5 mag quake.