6.3 is plenty strong to do significant damage depending on local conditions. Fortunately the Big Island is the kind of solid ground that generally does better in strong earthquakes than other compositions and it sounds like damage isn't too bad.
For comparison the Northridge quake in '94 was 6.7 and the Loma Prieta (San Francisco) quake in 1989 was 6.9.
The Richter Scale is a log10 scale so a 7.0 has ten times the shaking as a 6.0 (and 32 times the energy) so 6.3 generally won't be catastrophic. The strongest earthquake in Hawaii was
7.9 in 1868. At 6.3, this one is the largest quake in the United States so far this year but there were three larger ones in 2005.