50 Years Later: Remembering the Great Alaska Earthquake and Tsunami of 1964
Date Posted: March 19, 2014
The most powerful earthquake ever recorded in North America occurred 50 years ago, on March 27, 1964. With a magnitude of 9.2, “The Great Alaska Earthquake” caused massive tsunamis that devastated the Alaska coastal communities of Valdez, Seward, Kodiak and Whittier, and caused widespread destruction along the U.S. and Canadian west coasts. The tsunamis caused an estimated $1 billion in damage and killed 124 people in Alaska, California and Oregon. Tsunami waves reached as far away as Hawaii. Scientists even measured a wave height of 219 feet in Valdez Inlet! The quake lasted approximately four minutes and powerful aftershocks continued for three weeks.
Earthquakes and tsunamis can happen anywhere, any time of the year, but Alaska is particularly prone to them because it sits on the convergence of two tectonic plates – the Pacific Plate and the North American Plate. At this boundary, the Pacific Plate is sliding beneath the North American Plate, causing the majority of Alaska’s earthquakes. Alaska can experience up to 24,000 earthquakes in a single year.
From Then to Now: Look How Far We’ve Come
The tsunami of 1964 was a wake-up call for America. In its aftermath, the U.S. established the National Tsunami Warning Center in Palmer, Alaska, one of two tsunami warning centers under NOAA that monitor and warn for tsunami threats around the clock, every day of the year.
Numerous advancements also have been made in the areas of science, technology and community preparedness since 1964. The invention of new tools and faster data processing have drastically improved NOAA’s ability to warn the public of tsunamis and to forecast their impact. Seismic network upgrades, coastal tide gauge network improvement, and the deployment of deep ocean pressure sensors (DART) that are specifically designed to measure tsunamis all provide the raw data that scientists need to detect a tsunami. These observations, coupled with automated earthquake processing systems and state-of-the-art numerical tsunami forecast models, enable NOAA scientists to quickly warn the public when a tsunami threatens the coastline.
In 1995, Congress established the National Tsunami Hazard Mitigation Program, a partnership led by NOAA that includes the Federal Emergency Management Agency, the U.S. Geological Survey, and 29 U.S. states and territories, to carry out public education, community response planning, and accurate hazard assessment. A major accomplishment of the program was the development of tsunami evacuation maps for populated areas along the U.S. Pacific Coast.
How to survive a tsunami
The most important aspects of surviving a tsunami are: knowing when one is about to strike and knowing what to do so you can act fast. Tsunami warnings are issued through television and radio, community sirens, local officials, text message alerts, wireless emergency alerts, NOAA Web sites and NOAA Weather Radio All Hazards. However, depending on where an earthquake occurs, some tsunamis can reach the coast within minutes, leaving little time to receive an alert so it is important to understand nature’s warnings.
Know nature’s warning signs:
- A strong earthquake, or one that persists
- A sudden rise or fall of the ocean tide
- A loud, roaring sound from the ocean
Know how to respond:
- Immediately move by foot inland to high ground outside the hazard zone
- If you cannot quickly and safely move inland, go to higher floors of a sturdy building
- Turn on your radio or television to learn if there is a tsunami warning
- Stay away from the coast until officials say it is safe to return. A tsunami may consist of more than one wave and can last for hours. The first wave may not be the last or the most dangerous.
During Tsunami Preparedness Week, March 23-29, NOAA and partners will promote tsunami awareness and safety, urge coastal residents and visitors to prepare themselves and their families for a tsunami, and encourage communities to become TsunamiReady.