[Rockhounds] Oregon Earthquake (s)

[Frederick Olmstead]

  Hi


  I was just checking the "net" for info about the "quake" in Oregon and
  came across this - of interest...

GeorgiaO
GA in VA fm CA (Carmel) 
__..--..__..--..__..--..__


  Oregon


    Earthquake History

A strong earthquake in Del Norte County, California, on November 22, 
1873, caused chimney damage in many places as far north as Port Orford, 
Oregon, and east to Jacksonville, California. The tremor was felt from 
Portland to San Francisco and onboard ships at sea. Chimneys were 
damaged (intensity VII) in the Portland area from an October 12, 1877, 
earthquake apparently centered in the Cascade Mountains.

Another severe shock affected Portland on February 3, 1892. Buildings 
swayed, and terrified people rushed into the street (VI). The earthquake 
was felt strongly at Astoria and Salem; the total area affected covered 
about 26,000 square kilometers. Some damage to buildings at Umatilla 
(VI-VII) resulted from a March 6, 1893, earthquake. Details on this 
shock are lacking.

On April 2, 1896, three shocks in succession awakened everyone in 
McMinnville (VI). The main shock was felt at Portland and Salem. A 
similar occurrence on April 19, 1906, awakened people at Paisley (V). 
Three additional shocks followed within 1 1/2 hours. A strong earthquake 
on October 4, 1913, in the Seven Devils Mountains of western Idaho broke 
windows and dishes (V) in the area. On May 18, 1915, a sharp local 
earthquake rattled dishes, rocked chairs, and caused some fright (V) at 
Portland; three shocks were reported.

Three shocks were felt at Fort Klamath (V) on April 14, 1920. The center 
was probably in the vicinity of Crater Lake. People in a small area 
around Cascadia felt an earthquake on February 25, 1921 (V). A shock 
that was probably rather strong in an unsettled region of southern 
Oregon occurred on January 10, 1923. Plaster fell at Alturas, 
California, and the tremor was felt strongly (V) at Lakeview, Oregon. 
The felt area extended to Klamath Falls. Another earthquake was felt 
widely over a sparsely settled area in eastern Oregon on April 8, 1927. 
The center was apparently in eastern Baker County; the maximum intensity 
(V) was noticed at Halfway and Richland.

A damaging earthquake occurred at 11:08 PM PST on July 15, 1936, near 
the State line between Milton-Freewater, Oregon, and Walla Walla, 
Washington. The magnitude 5.75 shock affected an area of about 272,000 
square kilometers in the two States and adjacent Idaho. Ground cracking 
was observed about 6.5 kilometers west of Freewater, and there were 
marked changes in the flow of well water (VII). Many chimneys were 
damaged at the roof level in Freewater; in addition, plaster was broken, 
and walls cracked. Similar damage was reported from Umapine. Total 
damage amounted to $100,000. There were numerous aftershocks up to 
November 17; more than 20 moderate shocks occurred during the night, and 
stronger ones were felt (V) on July 18 and August 4 and 27.

A shock of intensity VI affected about 13,000 square kilometers in the 
vicinity of Portland on December 29, 1941. A downtown display window was 
shattered, and a few other windows were broken in other parts of 
Portland. The earthquake was also felt strongly at Hillsboro, Sherwood 
(where many were frightened), and Yamhill. The felt region extended into 
Washington; Vancouver and Woodland experienced minor damage.

On April 13, a major earthquake (magnitude 7.0) caused eight deaths and 
an estimated $25 million damage at Olympia, Washington, and a broad area 
around the capital city. The depth of focus was estimated to be slightly 
greater than normal, which, in part, accounted for the large felt area - 
388,000 square kilometers in the United States. In Oregon, widespread 
damage was observed, several injuries occurred at Astoria and Portland. 
A maximum intensity of VIII was experienced at Clatskanie and Rainier, 
where many chimneys twisted and fell, and there was considerable damage 
to brick and masonry.

Minor damage in the Portland area resulted from a December 15, 1953, 
shock. There was one report of a cracked chimney and slight damage to 
fireplace tile (VI). Additional reports of plaster cracking were 
received from Portland and Roy, Oregon, and Vancouver, Washington. The 
total felt area covered about 7,700 square kilometers.

Similar damage occurred at Salem on November 16, 1957, from an 
earthquake felt over a land area of 11,600 square kilometers in 
northwestern Oregon. The tremor frightened all in the city (VI) and 
caused some cracked plaster in West Salem.

On August 18, 1961, another earthquake caused minor damage at Albany and 
Lebanon, south of the 1957 center. The magnitude 4.5 shock was felt (VI) 
by all in the two cities. Two house chimneys were toppled, and plaster 
cracked. The felt region extended into Cowlitz County, Washington; the 
total area was about 18,000 square kilometers. Portland experienced 
another moderately strong shock on November 6, 1961. Slight plaster 
cracking (VI) was the principal damage reported. Also, part of a chimney 
fell, and windows and lights broke. The earthquake was felt over a large 
area (about 23,000 square kilometers) of northwestern Oregon and 
southwestern Washington.

A series of earthquakes near the Oregon-California border began on May 
26, 1968, and continued daily through June 11. At Adel, old chimneys 
fell or were cracked, and part of an old rock cellar wall fell (VI) from 
a magnitude 4.7 tremor on June 3. Some ground fissures were noted in 
Bidwell Creek Canyon, near Fort Bidwell, California. The total felt area 
in the two States covered 18,000 square kilometers.

Numerous other shocks located in California, Idaho, Nevada, Washington, 
and offshore points affected places in Oregon. The 1959 Hebgen Lake, 
Montana, earthquake was also felt in the State; slight damage was 
reported at Richland.

Abridged from Earthquake Information Bulletin, Volume 8, Number 3, 
May-June 1976, by Carl A. von Hake.

For a list of earthquakes that have occurred since this article was 
written, use the Earthquake Search. 
<http://neic.usgs.gov/neis/epic/epic.html>

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