File talk:Moment Magnitude.gif

Dubious image

I find this image dubious in its source and status, its derivation, and its utility.

The documentation gives the the creator as "unknown", while the source is given as http://www.fhwa.dot.gov/bridge/tunnel/pubs/nhi09010/13.cfm/, which redirects to https://www.fhwa.dot.gov/bridge/tunnel/, where no such image is found. There is an archived version showing the exact image, attributed to "Heaton, et al., 1986" (available here). The image there (figure 6, p. 193) has the same curves, but lacks the grid and box. Heaton et al. provide no details on how the graph was constructed, or where they might have gotten it, but other sources say it was orignally from Kanamori 1983 (available here), where there is a very similar graph (fig. 4b, p. 193). Although there is some evidence the Heaton et al. figure may have been created in 1982, the addition of the Mjma curve suggests it was derived from the Kanamori graph, or at least from the same data.

Needless to say, the articles the figures appear in are copyrighted: Heaton et al. by D. Reidel Publishing Company (1986), and Kanamori by Elsevier Scientific Publishing Companay (1983). It is not clear that any of the authors come under the U.S. federal employee exception.

The basis and derivation of both of these figures is unexplained. Examination of Kanamori suggests as few as two sources (from 1956 and 1978), with a total of 25 data points. This is an extremely thin basis for showing any kind of "Relations between various magnitude scales."

While an illustration of the variance between magnitude scales would be informative, this figure is somewhat misinformative: it is overly precise, suggesting less variance than is actually seen. And I think many people would have difficulty understanding what is being shown.

For these reasons use of this figure (and any similiar derivations) should be deprecated. Its unclear sourcing and possible copyright violation may warrant deletion. J. Johnson (talk) 21:33, 31 March 2019 (UTC)