The link supplied is over simplified with regard to waves, and more importantly swell propagation, however even this link includes the phrase:-

"But even when you feel no wind at all, you may encounter large swells created by distant storms."

When considering wave power, it is necessary to differentiate between:-
Wind generated waves - can be described as the waves created by wind blowing at that place and time.
Swell waves -  waves that are generated elsewhere and have travelled from their place of origin.

The comment with reference to the short time interval before the effects of a tsunami are felt is misleading.  Wave speed is directly related to wavelength, waves due to seismic disturbance typically have wavelengths measured in hundreds of kilometers as opposed to tens / hundreds of metres for normal swell.  The effects of distance storms can be felt many days after the storm in distance locations.

I am aware of 2 companies with differing approaches to wave power, with systems approaching commercial reality.

http://www.oceanpd.com

http://www.oceanpowertechnologies.com

It will be interesting to watch thier progress as they attempt to scale up.

Dave.