A Whole Lotta Shakin' Goin On

The Christmas Day tsunami that destroyed parts of Thailand and Banda Aceh were landmark events in that they were the first major wave disasters of the digital age. Near instant footage of the devastation and even of the actual events were viewed by millions of people. The word tsunami, once just in the vocabulary of ocean dwellers, was now understood by many. This is in contrast to a summer day in 1985 when there was a minor earth quake off the coast near Sitka. It happened around mid-day and our town leaders here in Petersburg decided to evacuate to high ground as a precaution. I remember walking as a group with my coworkers to the high school, which is located on a bit of a hill. One of them, new to Alaska and swept up in the excitement of the moment, finally mustered up the courage to quietly ask me “What’s a tsunami?”

The story of Lituya Bay is one almost every fisherman knows. Anyone who has been in a boat, large or small, on the ocean knows the unforgivingness of waves. We’ve all had that apocalyptic vision of somehow riding out the big one. Petersburg has it’s own version of the Lituya Bay story. Tlingit people tell the story of a village being destroyed by a killer wave prior to European exploration in Alaska. I have not seen his story in print, however, Sealaska (the Native corporation) just selected this area, Bock Bight as one of historical significance. From the Google photo you can see remnants of recent slides coming of the mainland mountains.

Close to home, we have another scenario that reminds us of the past. It is about 5 miles across from Horn Cliffs to Petersburg. There, the steep cliff face of the mountains rise up to an elevation of over 2500 feet while plummeting nearly straight down another thousand feet below the water surface.






Tsunamis can reach up to 400 miles per hour in the open ocean. That means a tsunami generated from a large landslide associated with an earthquake event would could reach Petersburg in under a minute. Historically, these lands are not as prone to landslide as further north in Thomas Bay. Also of significance is the fact that the closest plate boundary is about 100 mile away, offshore. However, the steep face, deep water, and short distance to town still make one take pause. (check out www.scribblemaps.com for tools to write on maps and photos)

Alaska Earthquake Information Center has a great site located here. They also have very detailed tsunami info/videos, including this great poster, located here (excellent tsunami videos).

This was a particularly fun module explore. Humans are in awe of natural cataclysmic events and the richness of resources available on the internet allow any teacher to make earth science fascinating to students. The ability to see detailed landscape on Google Earth and track real-time data increase the understanding and relevancy to the learner. The TD video “Living on the Coast” is a great model for students comparing and contrasting the natural history of two or more “coastal communities” with the end result of having a better understanding of both their own "home" and our "home", Earth.