Saturday, February 27, 2010

I'm ok


There was an 8.8 magnitude earthquake near Santiago, Chile this morning that had my family worried due to the news of tsunami concerns.

We're all OK and I'm safer at sea. Why? Well, here's a quick lesson in how tsunamis work, thanks to wikipedia:

"While everyday wind waves have a wavelength (from crest to crest) of about 100 metres (330 ft) and a height of roughly 2 metres (6.6 ft), a tsunami in the **deep ocean** (where we are) has a wavelength of about 200 kilometres (120 mi). Such a wave travels at well over 800 kilometres per hour (500 mph), but due to the enormous wavelength the wave oscillation at any given point takes 20 or 30 minutes to complete a cycle and has an amplitude of only about 1 metre (3.3 ft).[10] This makes tsunamis difficult to detect over deep water. **Ships rarely notice their passage.**

As the tsunami approaches the coast and the waters become shallow, wave shoaling compresses the wave and its velocity slows below 80 kilometres per hour (50 mph). Its wavelength diminishes to less than 20 kilometres (12 mi) and its amplitude grows enormously, producing a distinctly visible wave. Since the wave still has such a long
wavelength, the tsunami may take minutes to reach full height. Except for the very largest tsunamis, the approaching wave does not break (like a surf break), but rather appears like a fast moving tidal bore. Open bays and coastlines adjacent to very deep water may shape the tsunami further into a step-like wave with a steep-breaking front."

In sum, the energy would have passed underneath us and would have appeared to us much like a normal wave.

1 comment:

  1. great! i was worried too. i checked this morning and didn't see a post from you, but also didn't see any news about ships being in danger. glad you are all ok, and now i know a little more about ocean dynamics :) that actually makes sense and i did learn something similar in class once. are you still en route back out to sea from dropping off the sick crew member? it did always feel a little scary being out in the middle of nowhere with no doctor. good thing we are healthy people!

    can't wait to talk to you once you get back!
    2 weeks until selection sunday!

    Jenna

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