Talk:1951 East Rift Valley earthquakes

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A fact from 1951 East Rift Valley earthquakes appeared on Wikipedia's Main Page in the Did you know column on 17 August 2009 (check views). The text of the entry was as follows:

Did you know... that according to Taiwan's Central Weather Bureau the earthquakes of Douliu, Meishan, Nantou, Hsinchu-Taichung, Zhongpu, Xinhua, the East Rift Valley, Hengchun, Baihe, and Jiji were the ten deadliest quakes to strike the island in the 20th century?

A record of the entry may be seen at Wikipedia:Recent additions/2009/August.

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Work needed.[edit]

I have added specific details in the infobox for the four quakes in the table; other details (such as local date/time and epicenter) could also be added.

The lead needs a source for "a series of 735 earthquakes" (which is bit of nonsense, lacking specification of the minimum magnitude) and for the data range. The magnitudes mentioned in the lead should be identified by which quake, and a magnitude scale specified. It should be noted that ANSS magnitudes (click on the "Origin" subsection) "have NOT been reviewed by a scientist" (emphasis in the original); the ISC values are preferred. And the ISC values are M_S. Anyone interested in expanding this article should check the ISC On-line Event Bibliography. ♦ J. Johnson (JJ) (talk) 21:10, 14 May 2019 (UTC)[reply]

I'm confused (a common state). This paper (I love the title) gives the following 12 significant earthquakes, with date, time and magnitude (M_L ) to which I've added the relevant ISC event numbers and the ISC-GEM magnitudes M_w 

10/21 21:34 7.3, 894821 7.48

10/22 03:29 7.1, 894824 7.23

10/22 04:28 6.3, 894825 6.70

10/22 05:18 6.1, 894826 6.46

10/22 05:43 7.1, 894828 6.96

10/22 12:48 6.0, 894832 6.58

10/22 20:52 6.1, 894840 6.27

10/23 01:19 6.1, 894842 6.56

10/23 08:55 6.1, 894844 6.31

11/24 18:47 6.0, 894987 not in catalogue, but 7.4 M_s  in bulletin

11/24 18:50 7.3, 894988 7.81

11/26 06:38 6.0, 894992 6.44

Our table lists the 2nd, 5th, 10th and 11th of these events, but not the 1st.

So, the paper lists four M7+ events and so do we, they're just not the same four. Why doesn't the ISC-GEM catalogue show the 18:47 event on 11/24? Why don't we show the 21:34 event on 10/21? Mikenorton (talk) 14:51, 16 May 2019 (UTC)[reply]

I don't know! (An also common state.) As to which four, I was going by the four in the table, which presumably reflects the selection made in the Chinese language sources that are (currently) the basis of this article. As to the GEM catalog, are you referring to an old printed version? Or the current on-line version? At any rate, I can think several possible explanations for these discrepancies, such as differences of magnitude scales, and subsequent recalculation. Or, considering the nature the cited sources, perhaps just sloppiness by non-seismologist writers. If we wanted to explore these matters further we might want a filled-in table that compared the various sources. Which certainly should include the paper you mention (yes, nice title). But I am inclined to leave that for whomever wants to re-write/expand the article. ♦ J. Johnson (JJ) (talk) 00:12, 18 May 2019 (UTC)[reply]

The ISC-GEM catalogue (downloadable here) is (as I understand it) different to the ISC searchable catalogue, which lists the initial parameters form various sources. In many cases there have been re-determinations of epicentral location, hypocentral depth and magnitude (see here), based on published papers, other catalogues or, where necessary, their own estimates based on established relationships. When the ANSS use ISCGEM numbers, this is the catalogue they're using. Mikenorton (talk) 14:04, 18 May 2019 (UTC)[reply]

For the 18:50 event the only magnitude the ANSS gives is a 7.8 Mw, citing the ISCGEM as of 2015-05-13 18:52:47 (as well as "US"=NEIC). I don't know what that catalog said then, but the current record says 7.8 MS, and 7.3 Mw. Which reminds me of something Emile Okal said, that about 2015 the NEIC stopped listing Ms to make the records "less confusing to the lay person". I have more confidence in the ISC On-line Bulletin, and unless there is some special circumstance I prefer ISC's latest data. ♦ J. Johnson (JJ) (talk) 19:46, 18 May 2019 (UTC)[reply]