Roundings, Conversions, Updates etc
I was just on Geonets web site and looking at the list on
NZ earthquakes Mag 4.0+ 1960-2014
1995 jumps out as very high numbers
I already knew this because of the M5+ NZ Blog Maps I created a few years ago
127x M5's and 5x M6's and 1x 7.2????
I got the data from Geonets search to create the maps in the first place and it only had 105 M 5+'s and 8 M6's!!!
Further investigation ( downloading the CSV file again) shows that to get the figures on the list they round off the numbers to 4.95, 5.95 etc, so a
4.951 say becomes a M5.0, 5.93 becomes a 6.0 etc.
Then I had a look at the last download I got in March 2014, it shows 103x M5's and 7x M6's, no 7's!!!
That "new" 7.2 is Mw and was originally 6.99ML East Cape Ridge Off NI N.Z 05/02/95, even I rounded it to 7.0ML
There was originally a 6.55ML near Hawera, Taranaki Bight 19/9/95, now showing as 5.8Mw !!
I can understand the ML to Mw conversion, but geez it really skews the lists when they are thrown in mixed together, and can cause confusion or
slanted analysis results.
I guess all I can do is write a few lines on my blog pointing this out, along the lines of "data up to 2015 is in ML"
Geonet (and the other Networks world wide ( U know who I mean ) should also make the caveat when they present data, such as on lists.
yeah I know they all have a disclaimer that use of their data at the users risk.
Looks like I might have to review and update everything once a year?
not sure if I want to do that, because already you can't compare pre 2015 data to post 2015 data because of the Mw/ML mixture.
edit on 04000000919115 by muzzy because: (no reason given)
Just did some sample downloads, 2011 to today, M5+
looks like up to end of 2011 they have been converting to Mw, mb, even MS in one case in 2011, but after 31/12/2011 its basically just M as the
magnitude type, which by default is taken as ML.
I'll just have to keep an eye on it, as they update "the gap" 2012-2014, at least I still have my ML ongoing for 2015.
edit on 04000000919115
by muzzy because: (no reason given)