The following is a guest essay by Mike Beck, lead scientist for The Nature Conservancy’s Global Marine Team and a research associate at the University of California-Santa Cruz. On March 11, 2011 he went to the shore in Santa Cruz to witness the arrival of the tsunami from the Japan earthquake.
The power of the sea is humbling; as a surfer I know this very well. With normal waves, every foot of face increases their power ten-fold.
I went down to the Santa Cruz boat harbor last Friday morning. I’d seen the devastation on Honshu island and at other sites in northern Japan, and wanted to see what effects the tsunami would have in my backyard. Because the Intergovernmental Oceanographic Commission (IOC) upgraded the Pacific Tsunami warning system after the Sumatran tsunami, I knew when the waves would reach Santa Cruz and how high they would be.
The waves arrived as expected around eight o’clock that morning. But while the prediction was that the waves would be small and fade after about 40 minutes, the destruction lasted for more than six hours. The surf battered docks and sank boats, many of them were people’s homes.
Every 20 minutes or so, the water would flow quickly out of the harbor, like a fast moving river. The rescue boats had to power hard into the surge just to stand still. The water in the whole harbor would drop more than five feet in about 10 minutes. Soon after, an even faster surge would bring the water barreling back towards shore. Boats and pieces of docks that had been snapped free were flowing back and forth with each surge, slamming into and dislodging other boats. (Watch here: warning, adult language)
Of course, this was absolutely nothing compared to what has happened to people in Japan; my heart goes out to them. The devastation there defies comprehension. What I saw in Santa Cruz was only a small taste from a wave that raced 5,000 miles across the entire Pacific Ocean in nine hours. The speed itself is mind boggling; it’s faster than you or I could fly to Japan.
Why were the effects in Santa Cruz so difficult to predict? In part, it’s because while our models work well in the open ocean, the nature of the coastline – the shapes of the sea floor and bays – add friction to the surging water. And the way that we have built and modified our coasts compounds this complexity and makes predictions much more difficult.
The Santa Cruz harbor, for example, is at great risk. The man-made harbor has a very narrow, jetty-constrained opening through which all the water must drain. It’s also very close to many canyons that funnel and direct the water even more.
These forces conspired to make it a very long and difficult day for the harbor master, vessel assist crews, and the many boats and business owners that depend on the harbor. The events remind us never to take the sea lightly and to think carefully about how we plan our living around the coast.
In my next blog, I’ll reflect on how nature can help to hold back some of what the sea throws at us.
(Image: The dock end broke during one of the later tsunami surges in Sanata Cruz, CA on 3/11/11. Image credit: Sequoia Hughes/Flickr via a Creative Commons license.)