March 15, 2011

Footage of the March 11 tsunami around the Pacific

Posted by Austin Elliott

Plenty of news organizations have been collecting the extensive footage of last week’s tsunami generated by the M8.9 earthquake in Japan, so following along with them is a great way to keep up with the utterly humbling images from the interface between humanity and this planet’s powerful nature.

In particular the BBC has compilations of video from Japan, CNN has a scary view, and the L.A. Times has some footage from the California coast.

A good place to start is with the BBC’s superb explanatory video describing how tsunamis form. Despite the ocean-wide impact of Friday’s tsunami ($50 million in damage along even the CA coast alone), the risk that the U.S. faces from a locally-generated tsunami varies depending on where you live. In particular, although the entire west coast is a tectonic plate boundary, only the northern portion of it is a subduction zone, capable of producing the huge displacements of the seafloor that spawn tsunamis. An L.A. Times article begins to explain that SoCal’s earthquakes don’t pose a tsunami threat.

Here are a couple of humbling tsunami videos from Japan that I haven’t seen widely circulated on the major English news networks. In each of these the incessant and ever-increasing influx of water is almost unbearable to watch and gives a clear sense of the power behind this natural phenomenon.

You can find the other videos here and in this overwhelming film posted on facebook.

Our plight here on the west coast of the U.S. pales in comparison to the utter destruction Japan is facing, but footage of the surge coming ashore in California and Oregon serves as an eye-opening reminder of the tsunami’s power. In this beautiful video we see the surge in sea level coursing through San Francisco Bay toward the coast of Berkeley.

In that video the incoming water has slowed and risen into an elegant series of waves, which crash ashore onto an exposed beach. The waves immediately inundate the shoreline, revealing the elevated sea level driving them. You’ll also notice sharp waves reflected from the shore, crossing the incoming waves almost perpendicularly. Great illustration of constructive and destructive interference.

The tsunami surges into San Francisco Bay on the morning of March 11. The bay bridge and hilly SF skyline are visible in the background. Photographed by Steven Winter. Thanks to http://www.geomika.com/blog/ for highlighting it.

There are many more videos of the wave entering San Francisco Bay, as well as some great time lapse views of other coastal areas, and an impressive shot of one surge barreling through Santa Cruz Harbor that clearly illustrates how so much damage was done by a relatively small wave.

Tidal gauge stations and buoys are another great way to view the effects of the wave all around the Pacific. In Japan, tide gauges are still recording rapidly oscillating water levels along the shore. These hardly compare to the water levels associated with the initial onset of the tsunami, but the Pacific ocean is still clearly in much more tumult than it was in the relaxed days before the quake.

Tidal gauging station from the central coast of Japan on March 11, recording the onset of the tsunami. The green line below is the "risidual," which is effectively the difference between the water level and the expected tide.

Check out other tidal records from Japan yourself:

http://www1.kaiho.mlit.go.jp/KANKYO/TIDE/real_time_tide/sel/index_e.htm

Thanks to friends, relatives, and colleagues alike for directing my attention to some of these amazing perspectives.