I'm on an around the world odyssey, which you can follow through my HuffPost postings. Well, my most exciting day is happening right in front of me watching the 8.8 Chile earthquake cataclysm on CNN from the Hotel Pulitzer in Amsterdam. Thus, from half a world away, I'm missing what I've long imagined: a graphic view of a major tsunami decimating Honolulu from my penthouse.
Let me clarify, for that is the last thing I would want. Fortunately enough, the latest scientific data seem to suggest a tsunami perhaps from one foot to seven feet striking Hawaii. But you never know, for the 8.5 Chile earthquake of 1922 caused havoc in Hilo Harbor, and 8.8 is three times more powerful. The underwater topography surrounding Hilo seems to amplify the effect, as history has shown.
The media have reported that the Chile earthquake was 63 times more powerful than the 7.0 Haiti quake, while others have mentioned a thousand times stronger. The reason for this discrepancy can be attributed to a change in the system. The Richter Scale was long the standard, and it turns out that 8.8 is about 60 times the "shake," or horizontal amplitude, of a 7.0 earthquake. However, the current official reporting system is Moment Magnitude, and while the power factor from a 7.0 to 8.0 increases by a factor of 10 using the Richter Scale, you need to multiply by 31.6 for the Moment Magnitude Scale. Thus, for the latter, a 9.0 is 31.6 times 31.6, or 999 (call this a thousand) times the expended energy of a 7.0 earthquake.
Thus, the Chile 8.8 is about 600 times stronger than the Haiti 7.0 using the Moment Magnitude Scale. However, the most powerful earthquake known occurred close to the present one in 1960, a 9.5, which generated a tsunami that killed 61 in Hilo, Hawaii.
According to GMA News, a 6 foot tsunami struck French Polynesia. Reports are coming in from various Pacific sites of similar wave amplitudes.
I'm now watching Hilo, live, with all ships at sea, for if you are sufficiently offshore, the wave will not be perceptible. However, Hilo Bay is now projected (11am Hawaii time) to be struck by a six-foot tsunami. You can also go to Planet Earth and Humanity and get the latest info.
Remember, though, that there can be a second and third wave, and sometimes, the later ones are more significant. Well, the Hilo tsunami is just happening, with waters appearing to be receding off Coconut Island at 11:19AM, just exactly as originally predicted. In any case, as a tsunami travels as fast as a jet plane, Honolulu is 30 minutes away (before Noon).
The worst part of this all (at 11:30AM) is the uncertainty. Those sirens beginning at 6AM, and repeating every half an hour or so, are unnerving. The scientific reports seem somewhat reassuring, but there is discoloration in the waters around Hilo and the Wailua River seems to be rising.
Well, now getting close to noon, and the 35-foot tsunami of 1960 will not be repeated in Hilo. At noon, unofficial inputs report on a 2 foot recession and 3 foot rise on the Big Island. So, yes, Hawaii is being impacted by a tsunami, but the all clear signal came. The latest news, though, can still be found at Hawaii Tsunami Information. Twenty two hours after the earthquake, the tsunami also caused some minor harbor problems in Japan.
By the way, to close this discussion, it turns out that the maximum height of a tsunami in the far field (1000 miles away or more) is about 30 feet. However, if there is a landslide of sufficient volume, moving fast enough, into deep waters, the resultant tsunami could be 300 feet or higher. At least, that is a theory that was somewhat exhibited in Lituya Bay (Alaska) in 1958. A wave of 1700 feet! My chapter 6 of SIMPLE SOLUTIONS for Planet Earth provides a possible worst case scenario for Seattle if such an event occurred where Hilo, of all the ironies, fell into the sea. Details can be found beginning with my 11September08 blog.