Seismology: Shaken Earth

As they viewed their shattered homes and the gaping fissures in their streets on Good Friday 1964, Alaskans suspected that they had survived one of the most violent earthquakes in history. Now, after three years of soundings and surveys, scientists of the Environmental Sciences Services Administration have compiled dramatic evidence to illustrate just how powerful the Alaska quake really was. In a detailed study, they report that it lowered mountains, raised sea beds, and made an impact halfway around the world.

Mountains on Kodiak Island and on the Kenai Peninsula near Anchorage subsided 7 ft. or more; the Kenai mountains moved laterally as much as 5 ft. In a 480-mile by 127-mile area off the Alaska coast, the ocean floor rose as much as 50 ft., the greatest quake uplift ever recorded. Near Valdez, Alaska, a slice of land 4,000 ft. by 600 ft. fell into the sea.

Some of the temporary effects were equally spectacular. Surging waves generated by the quake reached as high as 220 ft. above sea level near Valdez. Some 2,800 miles from the epicenter, at Hilo, Hawaii, the seismic sea wave caused the ocean to rise 121 ft. And in Antarctica, 8,445 miles away, the tsunami was recorded 221 hours after Alaska had shaken, having crossed the vast expanse of water at 430 m.p.h.

The shock waves from the earthquake also caused seiches (water oscillations) in rivers, lakes and protected harbors along the U.S. Gulf Coast from Texas to Florida. At New Orleans, a drawbridge tender felt the span shake beneath his feet, and a sudden rise of from 1½ to 5 ft. in the level of the Mississippi caused docked vessels to break loose from their moorings. In Atlantic City, N.J., (more than 4,000 miles from the quake), the thorough scientists report, water sloshed over the top of a hotel swimming pool.