“Mayday, Mayday – Edrie in Lituya Bay – all hell broke loose – I think we’ve had it – goodbye!”
An earthquake of magnitude 7.5 triggered a landslide in this bay, which had an entrance only 10 meters wide, so the tsunami/wave quickly dissipated in the open ocean. A more scholarly treatment, written by Charles Mader and Michael Gittings, reported that the run-up was 520 meters, and that there were 5 earlier giant waves over the last century and a half, with the most recent previous one of 150 meter height in 1936. Yes, you will want to avoid Lituya Bay.
Some basic principles regarding earthquakes and tsunamis:
o About Richter magnitude—7 is a major earthquake, with an equivalent TNT explosive weight of 32 million tons, while an 8, which is ten times more powerful (one billion tons of TNT), is a great earthquake. Only a very few 9’s have been recorded, including the monumental December 26, 2004 Sumatra quake. A 10.0, which has never been measured, would be the equivalent of 1 trillion tons of TNT and would represent a San Andreas type fault circling the Earth. There was a four hour ABC TV movie, 10.5 Apocalypse, in May of 2006, but this one was, of course, fictitious and literally divided the United States into two. A theoretical 12.0 magnitude has a seismic energy yield of 160 trillion tons and is said to approximate a fault through the center of the planet, and coincidentally, in energy terms, is about the daily reception of all the solar energy. Finally, seismologists are more and more using moment magnitude, which more closely represents the danger, and is represented by M with a subscript w. However, for our purposes, as the Richter magnitude and that of professionals are about the same, we’ll stick with Richter.
o There have been 3667 significant earthquakes since 1977, which created 107 major tsunamis.
o Nearly 90% of all earthquakes occur in the Pacific Ocean, usually in the vicinity of the Ring of Fire, that starts through New Zealand, wends north of Australia, up the coast of Orient to the Aleutians, east to Alaska and down the western coastline of North and South America.
o Of the 1488 recorded tsunamis, 76% occurred in the Pacific, with 86% being caused by earthquakes, 5% volcanoes, 3% landslides and 5% combinations.