The magnitude 5 Point Robinson earthquake of January 29, 1995 had its epicenter 15 miles south of Seattle but was widely felt in western Washington. The causative fault is controversial but it may be related to the Seattle Fault (14kb). The Seattle Times agreed to publish an earthquake questionnaire soliciting information from the public about the effects of the earthquake that was to be returned by regular mail. The Seattle Times also published the fact that anyone could fill out the questionnaire via e-mail or a WEB-form on the internet, if preferred. We received about 1000 e-mail responses, 1000 WEB responses, and 6000 responses via regular mail within a week and a half.
Our preliminary results indicate that electronic methods are now very effective in constructing "intensity" (or damage) maps because of the widespread availability of internet access. The electronically submitted questionnaires can be analyzed considerably faster that regular mail responses. In the near future, it will be possible to create intensity maps within a few hours or days after an earthquake. Such maps could be useful to earthquake response teams.
An index map (17kb) shows the locations where we obtained both electronic and regular mail responses. From each questionnaire we computed a Modified Mercalli intensity. The computed intensities were grouped by zip code and all intensities within a single zip code were averaged together. The position of each zip code area is shown as a dot on the map. The intensity values obtained via e-mail/WEB questionnaires are contoured on a map (27 kb) for the area shown as a red box on the index map. The resulting intensity map based on 2000 e-mail/WEB questionnaires can be compared a traditional intensity map (22kb) computed from about 100 questionnaires submitted in a standard procedure by US Postmasters to the US Geological Survey (map, courtesy of Margaret Hopper and Jim Dewey of the USGS).
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UW Dept. of Earth and Space Sciences ..... PNW EARTHQUAKES
