At 1:14 AM HST an 8.3 moment magnitude earthquake struck near the Kuril Islands in the northwest Pacific Ocean prompting the Pacific Tsunami Warning Center to issue a Tsunami Watch for Hawaii. The watch was cancelled around 5 AM when it was determined that a large destructive tsunami had not been generated. PTWC and Civil Defense officials cautioned that even though the tsunami was not large, there would be potential hazards to those in and near the water from strong or unusual currents and sea level fluctuations.
The first tsunami waves reached Hawaii around 7:20 AM. Rapid changes in sea level were reported around the state including 60 inches at Kahului, 45 inches at Haleiwa, and 18 inches at Waikiki. Surges of water overran the parking lot at the small boat harbor Nawiliwili Bay on Kauai and reached the highway near Laniakea on Oahu.
A tsunami is made up of a series of waves generated when an earthquake or underwater landslide displaces a significant amount of water. The resulting wave ripples away from the origin traveling as much as 500 mph in the open ocean. The size and behavior of the waves as they reach shore depends greatly on the geography of the coastline and the bathymetry of the ocean floor and consequently can vary significantly from one location to another.
This variety can be seen in the data recorded at NOAA's National Ocean Service tide gauges around the state. Graphic and text representations from several of these gauges are linked below. The red line represents actual measured sea level height and the green line the departure of the observed from the predicted height (blue line). Arrival of the tsunami wave is evident in the sudden swings in both the red and green lines. Some sloshing is still evident a day later as the waves set up seiches in the bays and echo across the basin.
More information on tsunamis, safety, and preparedness is available from the National Weather Service and from County Civil Defense Agencies.
Sea Level Height Measurements November 15-16, 2006
* Please note that these preliminary raw data have not been quality controlled by NOAA/NOS and should be used with caution.