March 11, 2009

Answer to quiz: Earthquake of 1964.

During my trip to Anchorage, Alaska my wish to visit the ghost towns of Hope and Sunrise located around Resurrection and Sixmile creeks was discussed with several people. I made the comment that the area looked much the way it did in 1896 when Soapy landed there, and I was immediately corrected by several Alaskans that the area drastically changed after the earthquake of 1964.

I had read a little and saw photographs of the damage taken in Anchorage but did not know just how big and destructive that earthquake really was until just a few days ago. Here is what I found.

"The second largest earthquake of the 20th Century and the largest ever recorded in the northern hemisphere, occurred in Alaska on March 27, 1964 (3/27/64 05:36:14.0 p.m., local time; 3/28/64 03:36:14.0 GMT). The earthquake had a magnitude 9.2 (Moment Magnitude) and caused extensive damage in Alaska. Local tsunami waves triggered by this earthquake were extremely destructive in Prince William Sound and other areas of Alaska. A Pacific-wide tsunami was generated which was destructive in Western Canada, Oregon, California and the Hawaiian islands. It was recorded by tide gauges throughout the Pacific. Even tide gauges in Cuba and Puerto Rico recorded sea level oscillations from that event. A Tsunami Warning was issued by the Tsunami Warning System in Honolulu for Hawaii and the West coast of United States and Canada. Regional Tsunami Warning Centers in Japan, Chile, the former Soviet Union and elsewhere, issued warnings. Combined, the earthquake and tsunami took 125 lives (tsunami 110, earthquake 15), and caused about $311 million in property loss (in 1964 dollars)." [That is equivalent to $2,188,357,968.64 in today's market.]

"Horizontal Displacements: "As a result of the 1964 earthquake quake, the net horizontal movement of the Pacific plate under the North American plate was about 9 meters on the average in a southeast direction, although some sections apparently moved considerably more. For example, Latouche Island area moved about 18 meters to the southeast."

"The area where there was significant damage covered about 130,000 km2. Major structural damage occurred in many of the cities in Alaska, but primarily in Anchorage. Most of the structural damage of other coastal towns was primarily caused by the resulting tsunami waves. Also, the nearly four minute duration of earthquake shaking triggered many sub-aerial and underwater landslides, avalanches and caused ground liquefaction. Earthquake damage from the earthquake was heavy in many other towns, besides Anchorage. Towns such as Chitina, Glennallen, Homer, Hope, Kasilof, Kenai, Kodiak, Moose Pass, Portage, Seldovia, Seward, Sterling, Valdez, Wasilla, and Whittier sustained considerable earthquake damage."

"Although almost 120 kilometers away from the earthquake's epicenter, Anchorage sustained severe damage. Earthquake shock waves lasting approximately 3 minutes caused extensive damage or total destruction to buildings and houses over a large area of approximately 30 city blocks, mostly in the downtown area. All utilities were disrupted throughout the city and the suburbs."

"Some areas near Kodiak were permanently raised by 30 feet (9.1 m). East of Anchorage, areas around the head of Turnagain Arm near Portage dropped 8 feet (2.4 m), requiring reconstruction and fill to raise the Seward Highway above the new high tidemark."

Sources:
* Earthquake page of Dr. George P. C.
* (Name unknown) president of Hope Historical Society

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