Photograph from Mainichi Shimbun/Reuters
A wall of water advances on Miyako, in northeastern Japan's Iwate Prefecture, on March 11, 2011.
The massive tsunami unleashed by the earthquake about 80 miles (129 km) east of the city of Sendai in northern Japan utterly destroyed cities along the island nation's east coast. Comparisons to the destruction of the atomic bombs visited upon Japan at the end of World War II were common, especially given that the flooding, which knocked out crucial backup cooling power at the Fukushima Daiichi nuclear power plant, triggered a nuclear crisis second only to the 1986 Chernobyl accident in Ukraine.
The energy released by the tsunami in fact greatly exceeded the destructive power of the atom bombs that hit Hiroshima and Nagasaki in 1945, estimates University of Illinois geologist Susan Kieffer, an expert on geological fluid dynamics. The tsunami's energy likely exceeded the explosive power of a megaton of TNT, or about 28 times the combined power of the two atomic bombs that hit Japan, she wrote on her blog, Geology in Motion. But Kieffer says the destructive power may have been much greater, perhaps 10 megatons, or 280 times the force of the atomic bombs. The difference depends primarily on how long the tsunami lasted, with her estimate ranging from 100 to 1,000 seconds.
At the upper end, that's the energy equivalent of 6.9 million barrels of crude oil, or 50 percent more than all of the oil Japan consumes each day.
The calculation also considers the velocity of the wave, which Kieffer estimated was about 220 meters (722 feet) per second based on the 30 minutes or so that it took to reach shoreline. Also, Kieffer used the wave's estimated open-ocean height at 7 meters (23 feet), and calculated that the wave was about 800 miles (1,300 kilometers) long, or about half as long as the coastline of Honshu, the island it struck.
هیچ نظری موجود نیست:
ارسال یک نظر