Extreme Waves

Fortunately, few of us on shore or in a boat have ever looked out to sea and seen a wave as tall as a 10-story building racing toward us, and in that instant known that there was no way to outrun it, no way to survive, and that our life was about to come to an end. Yet, such waves exist, waves that appear suddenly in the open ocean, waves big enough to break the back of modern crude oil tankers or bulk container ships and send them to the bottom before an SOS can be sent. Recently two large cruise ships were front page news when they suffered damage and injured passengers after being hit by rogue waves. Still more horrific was the disaster that overtook Southeast Asia on December 26, 2004, huge waves, hundreds of thousands dead. This book traces the origins of waves, explaining how calm seas change to stormy seas under the influence of winds, how waves propagate, the effect of currents, tides, and earthquakes, and how ships and offshore structures respond to extreme waves. There is one hundred real life stories included in the book to illustrate the important topics-stories from U.S. Navy admirals responsible for nuclear aircraft carriers, to Brad Van Liew, who sailed single-handed through the most dangerous oceans in the world, to win the recent "Around the World Alone" race. There are ships that were hit and survived, and other vessels that did not survive. Each incident entails heroism, mostly unsung, beyond that which we can imagine experiencing. Tsunami are not a result of rogue waves, but arise from earthquakes or submarine landslides. In the open ocean, a tsunami might pass undetected; it is only as it nears shallow waters near coastlines that its true terror and power are revealed. Here, in shallower water, large waves can occur. By understanding the mechanism of tsunami formation and propagation-and knowing the warning signs-many lives can be saved. New research using satellites to scan the world's oceans and measure wave heights has revealed that giant waves-so-called rogue waves, 20 to 30 meters (65 to nearly 100 feet) high-are not only real and not a figment of a sailor's imagination, but they occur far more frequently than previously believed. They can occur anywhere, when conditions are right, rising up suddenly to strike a ship, perhaps sinking it, before dissipating once again into the endless waves we are accustomed to seeing. What defines a rogue wave is exactly this-it appears suddenly, seemingly out of nowhere, and is two or three times higher than that average height of the waves preceding or following it. Sadly, there is no single standard for the structural design of merchant ships to resist heavy seas. Consequently, different classes of vessels have varying abilities to survive a rogue wave encounter. Most commercial vessels are not designed to withstand waves much greater than 10 to 11 meters (35 feet) in height, and as a consequence a surprising number of large ships are lost every month-sometimes several a week-somewhere in the world, due to rough weather and encounters with extreme waves. The tragic loss of crews-typically 30 sailors on a modern merchant vessel-is a scandal that unfortunately receives scant attention. Today, with new knowledge concerning extreme waves, we have the ability to ensure that vessel losses become a rare event. Advanced warning systems and education of coastal populations can likewise greatly reduce the death toll from tsunami.