This timelapse shows the dropping tide in Seldovia, beginning around the time that the 27 Feb 2010 tsunami was forecast to arrive. The tide gage in Seldovia measured the tsunami waves as several inches tall, with periods around ten minutes.
The dropping tide does appear to vary a bit, perhaps slowing as tsunami waves come in and then speeding up as they retreat. Also the barge in the distance moves back and forth, probably moved by the tsunami waves going up the bay.
The timelapse photos were 10 seconds apart, displayed 30 frames per second.