The time skew of the events is small, but does exist. They're all within minutes of the 9:31am gmt earthquake, getting longer as you get away from the epicenter. i.e, way faster than a tsunami travels, but about how fast an earthquake travels. (Earthquakes spread in x miles per second, tsunamis in x miles per minute)
I _think_ what you're seeing is the pressure sensor picking up the earthquake and converting it to a water column height.
The water column height on these buoys is a pressure transducer on the floor of the ocean (http://www.ndbc.noaa.gov/dart/dart.shtml)
The time skew of the events is small, but does exist. They're all within minutes of the 9:31am gmt earthquake, getting longer as you get away from the epicenter. i.e, way faster than a tsunami travels, but about how fast an earthquake travels. (Earthquakes spread in x miles per second, tsunamis in x miles per minute)
I _think_ what you're seeing is the pressure sensor picking up the earthquake and converting it to a water column height.