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Transcript for America\'s New Frontier, segment 08 of 11
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The GLORIA imagery from the Gulf of Mexico gives the first complete look at the huge fan of sediment deposited by the Mississippi River. Its network of channel waves and loads of sediment extend beyond the limit of E. E. Z., covering more than sixty thousand square miles of ocean floor. This three-dimensional enhanced GLORIA image from the eastern Gulf of Mexico shows the dramatic submarine cliffs and canyons of the Florida Escarpment. And off Puerto Rico, this gigantic submarine landslide scar has a volume equivalent to more one-and-a-half million times that of the Houston Astrodome. Its presence hints of the catastrophic processes actively shaping islands in the Caribbean and elsewhere.
The Atlantic margin GLORIA survey in nineteen eighty-six revealed a complicated network of submarine channel ways resembling the tributaries of river systems seen on land. By locating these channel ways and other hazards such as submarine landslides, the images have already proven useful for laying out precise routes for transatlantic fiberoptic cables.
The GLORIA survey of the Bering Sea provides an important look at the ocean floor of America's richest fishing grounds. Several large submarine canyons occur on the margins of the Bering Sea, including Zumchug Canyon which is the world's largest by volume. A related discovery showed that several submarine channels issue from the mouths of these canyons and extend for hundreds of kilometers across the deep ocean floor of the Bering Sea.
The area I've been mainly working with on the GLORIA project has been the Gulf of Alaska area which stretches from Dixon entrance over here on the Canadian-U. S. border on around to through the Alaska Peninsula, and one of the neat things we've been able to do with the GLORIA data that we've never been able to do before is follow a fault system along southeastern Alaska called the Queen Charlotte Fairweather Fault System. This fault system is about the length of the San Andreas Fault System, and we know from the earthquakes that have occurred along it it has about the same power and the same danger as the San Andreas Fault System. Well, the major difference is that thee San Andreas Fault System is almost entirely exposed. It's on land. We can look at it. We can walk on it. We can take pictures of it. The Queen Charlotte Fairweather Fault System is entirely submerged. The fun thing about the GLORIA program, when we got over along the Queen Charlotte Fault System - all of the sudden we could see the fault clearly for the first time, and it's - we could see the active trace, and one of the fun things about that was, before we saw it on the GLORIA images, we had mapped it in the wrong place. Now we know where it is.
Well, in the Aleutian Islands, at any rate, great earthquakes occur, some of those larger than the great San Francisco earthquake. But the bad thing about the Aleutians is that they generate great tsunamis, or tidal waves some people call them, great seismic sea waves. Not many people live in the Aleutians, but this great tidal wave moves southward, runs into Alaska, runs into Washington, Oregon, and California, and especially Hawaii, and in nineteen forty-six hundreds of people were killed in Hilo, for example, from an earthquake, a great one which occurred in the Aleutians. Well, part of the GLORIA work up here was designed to determine what sort of fault structures did we have on the sea floor, some which might be related to the generation of the tsunamis? We had other geophysical data which indicated to us something about the structures, but we didn't know how to connect them. How big were they? Well, what GLORIA almost could uniquely do for us was to take this sort of sound image of the sea floor and tie in these structures, that they were, in fact, connected, and once we realized that, then we could assign great risks to these structures and start to understand how they're being developed and why the earthquakes were recurring, repeatedly sometimes, in the same area, which is where the research needs to go next.