why do seiches occur far from epicenters?

Answer 1

Wikipedia has a very nice discussion of Seiches and the various mechanisms that cause them. http://en.wikipedia.org/wiki/Seiche
As far as earthquake generated seiches, when the frequencies of ground tremors match the resonant frequencies of small containers of water-like swimming pools, seiches can be generated. It is the periodicity of the tremors, not the distance from source, that matters. Tsunamis (generated by quakes or submarine landslides) can also generate seiches in bays, for instance, which have resonant frequencies in synch with the tsunami wave trains.
Winds also cause the phenomenon. Seiches are well-known on the Great Lakes and were first described in Swiss lakes.