The 1964 Tsunami Strikes Valdez

The map above shows two different locations for Valdez. The first, Old Valdez, represents to the town's location before the 1964 tsunami, and the second, New Valdez, its location after the tsunami. The reasons for this move are clear if one examines the chain of events that occurred following the 1964 earthquake.

The town of Valdez (Old Valdez) was built on unconsolidated deltaic sands and gravels, which are extremely unstable during shaking. Thus, the shock waves from the 1964 earthquake that struck Valdez immediately caused the sediments under the waterfront area to spontaneously liquefy (a condition where sediments essentially behave as a liquid, loosing all load bearing capacity), which caused a large section of the delta (approximately 4,000 feet long by 600 feet wide) to slump into Port Valdez. Aside from sending most of the Valdez Port Facilities to the bottom of Port Valdez, the slump displaced a large volume of water, generating a local tsunami. Since all of this occurred before the earthquake shaking ended, the town had no warning at all, and all people on the town docks at the time were killed by the tsunami. The combined effects of the earthquake, and the 30- to 40-foot local tsunami, destroyed most of the waterfront, and caused damage a considerable distance inland. To make things worse, the forces caused the tanks at the Union Oil Company to rupture, which started a fire that spread across the entire waterfront, finishing off the few structures still standing. The photos below illustrate the scene at Valdez in the days following the tsunami. Smaller waves from the main tectonic tsunami struck Valdez several hours after the local tsunami, but their effect was minimal, as there was nothing left too destroy.

In addition to ruining Valdez, the local tsunami affected other areas of Port Valdez as well. At Cliff Mine the tsunami runup was 170 feet (see figure), and a runup in excess of 100 feet was reported in Shoup Bay (see figure).

After suffering through the tsunami experience of 1964, the town of Valdez was rebuilt at it's present location (New Valdez), situated at a higher elevation, and on more stable ground, to offer greater protection from tsunamis.

 

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