In a previous project, we compiled a comprehensive collection of source material on Cascadia earthquakes prior to 1928, including over a dozen earthquake catalogs and about 400 other sources; including newspaper articles, technical reports, weather observer's records, and diary entries. The MS-ACCESS format Cascadia data base 1793-1929, and other web pages on historical seismicity in Washington and Oregon are available via the web: http://www.geophys.washington.edu/SEIS/PNSN/HIST_CAT.

Under the current project we have continued to search for additional source material for earthquakes prior to 1928, including a search of Native American literature for evidence of the Cascadia megathrust earthquake of 1700, known from paleoseismic evidence and historic records of a tsunami that struck Japan in January of 1700.

We also scanned and placed on the World-Wide-Web (WWW) a large volume of information on the 1872 North Cascades earthquake (estimated magnitude 7.4), and on more recent Washington and Oregon earthquakes, documented in United States Earthquakes, a U.S. Department of Commerce, Coast and Geodetic Survey publication that began in 1928.

We have continued to add material to our MS-ACCESS Cascadia database 1793-1929. The online version is available via the WWW, and an updated version is available on request.

An web-accessible online version of "United States Earthquakes" entries for Washington and Oregon from 1928 through 1970 is now available. "United States Earthquakes" was an annual publication of the Coast and Geodetic Survey that, beginning in 1928, provided fairly complete descriptions of earthquake effects and included macroseismic maps for larger earthquakes. These maps indicate the extent and geographic distribution of strong shaking. We scanned and proofread entries from "United States Earthquakes" for Washington and Oregon from 1928 through 1970. We have formatted these for the World-Wide-Web, and they may be viewed at: http://www.geophys.washington.edu/SEIS/PNSN/HIST_CAT/isoseismals.html. Although "United States Earthquakes" is well known to seismologists, the information it contains has not been readily available to the general public. After 1970, an instrumental network was installed, and accurate information about earthquake magnitude and location after that date are available from the Pacific Northwest Seismograph Network (PNSN).

Newspaper articles from 1872 and 1873 detailing the effects of the 1872 North Cascades earthquake are now accessible on-line. The 1872 North Cascades earthquake, estimated magnitude 7.4, is the largest earthquake to occur in Washington or Oregon since settlement by Europeans. It occurred in a sparsely populated and extremely rugged area, and its source fault has not yet been identified despite considerable study. Some of the most thorough studies of this earthquake were carried out in the mid 1970s when nuclear power generators were being considered in western Washington. During the 1970s an exhaustive search was made for newspaper articles, letters, and other contemporaneous and historic accounts of the earthquake and its aftershocks, and these were transcribed in two main "gray literature" references (Weston Geophysical Research Inc, 1976, The 1872 Earthquake, Significant data and conclusions, Prepared for United Engineers & Constructors, Inc. and Coombs, H.A., W.G. Milne, O.W. Nuttli, and D.B. Slemmons, 1976, "Report of the Review Panel on the December 14, 1872 earthquake"). "Gray literature" is a term used to describe sources like technical and engineering or environmental reports that are one-of-a-kind, receive a limited distribution, and are not indexed in databases like Science Citation Index, GeoRef or Geobase.

Because these sources contain valuable information that is virtually inaccessible, we scanned and proofread the all of the 1872 newspaper and letter accounts contained in the Weston Geophysical Research Inc, 1976 and Coombs et al., 1976 reports. The transcribed accounts are available online through the WWW:

We made a special study of the possible aftershocks of the 1872 North Cascades earthquake. We reviewed and organized newspaper reports of earthquakes in the months following the main shock. This study is available as a series of web pages at:

Indian myths and legends were searched for evidence of very large coastal earthquakes on the Cascadia subduction zone. A series of 7 such earthquakes in the last 3,500 years is known from geologic evidence. The most recent of the Cascadia megathrust earthquakes occurred in January of 1700, and caused a tsunami which is documented in Japanese historic records. We reviewed Pacific Northwest Indian tales and legends for stories that might record the 1700 megathrust earthquake. The Indian stories are very unlike newpaper reporting, and large parts of the oral literature of the Pacific Northwest are missing. However, some stories do exist. We discovered stories from several different Indian groups that share common story elements. Although it is not possible to place a precise time frame on the events described in the Indian legends, they suggest that an account of a historic event has been overlaid on a much older myth. The stories are consistent with strong shaking felt over a wide area and accompanied by severe tidal disturbances. We are asking folklore experts to comment on our findings..

Information about past historic earthquakes is used to evaluate seismic hazards.

We are refining and extending our existing database of information on over 500 historic earthquakes in Washington, Oregon, and British Columbia between 1793 and 1929. During this contract period we continued to search for additional source materials for earthquakes prior to 1928. We also produced on-line Web pages with information on Cascadia earthquakes from 1928-1970. Another set of Web pages provides detailed information on the effects of the 1872 magnitude 7.4 North Cascades earthquake, and events that may be its aftershocks.

We searched for Native American stories about the magnitude 9 Cascadia megathrust earthquake of 1700. This earthquake is known from paleoseismic evidence and historic records of a tsunami that struck Japan in January of 1700. Pacific Northwest Indian stories about strong shaking accompanied by tsunamis do exist, although they are sparse and can be difficult to recognize and interpret.

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