reply to post by Agarta
Hi Agarta. I meant to reply to this earlier.
From your reference:
Below is a graph showing how the number of all magnitude earthquakes has grown over recent years.
Now whilst I grant that the author does say that this graph would expect to show an increase as there are more stations, one has to ask if that is the
case why bother to display the graph at all as it is statistically completely useless?
There is another site which does the same and uses these silly graphs. Rather than type it all out again I will direct you here to
"Does the number of Earthquakes matter?"
I note also that he gives an attribution for the graph of Graph plot for "all magnitude" earthquakes reproduced from DL Research paper
This web site is no different from his own and is not the "research" site it is made out to be. In fact the site owner even makes a request for anyone
to give him more sources of data on the web page! (Muzzy - you will have a barrel of laughs at this crowd.)
So back to the report.
You need to look at Muzzy's Worldwide Quake Mapping Project
That is a project that is based on good research and many data sources. In particular take a look at the graph for 1910 to 2011 which definitely does
not back up this sites assertions.
and they say:
When there are multiple earthquakes (over 7.0) occuring within 5 days of each other in the same geographic area, only one has been counted. This
may result in slightly different (lower) numbers for earthquakes than might otherwise be listed, although consistancy in this approach makes
historical comparisons more reliable, as large after-shocks were not always recorded (in addition to the "main" quake) in previous decades.
Not sure what to make of that one! The Moro gulf would look at bit sad! This is statistical nonsense again. There are very good reasons why historical
quakes are not so well recorded. You only have to look at New Madrid and the argy bargy over earthquake sizes. In addition as Muzzy would i have no
doubt confirm, many of the older catalogues are only in intensity, and there is really little effective translation from intensity to magnitude. Most
of it is guesswork.
For the purposes of statistical recording below, only those earthquakes registering ABOVE 6.9 (ie a level of 7.0 or above) are now counted below.
Major earthquakes, rather than the more regular and frequent lower intensity earthquakes, are judged to have a greater impact on geographic reach and
damage, and are more likely to be accurately recorded over a longer period of history.
Well this sounds reasonable doesn't it? No, actually. I will come to that is a minute.
For example, between 1986 and 1996 (incl), a period of 11 years, there were "just" 15 earthquakes listed by USGS of magnitude 7.0 or
I find this statement very odd.
Magnitude 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
8.0 to 9.9 0 0 0 0 2 2 1 0 1 0
7.0 to 7.9 18 16 13 12 11 18 14 16 11 18
1990s from USGS
I count 108 for 1990 to 1996 so where is the figure coming from? Is he suggesting that the missing 93+ are all aftershocks that he is not counting?
Sorry, but the dates for earthquakes listed here are in reverse order to accepted international usage (ie they are in US format which is
:shk: Not only is that not US format, it is Asian format, it is also the accepted way of displaying dates for the very good reason that it is
sortable. To apologise for that makes me suspect that the author really does not have much of a clue.
So finally why did his statement not seem reasonable?
He is making an assumption that mag 7+ will be recorded all over the world - at their correct magnitudes.
The marked line is Graffenberg in Germany where the earthquake was recorded as a 7.6. So what was this quake?
ot = 05:46:23.70 +/- 2.96 NEAR EAST COAST OF HONSHU, JAPAN
lat = 38.322 +/- 6.1
lon = 142.369 +/- 8.9 MAGNITUDE 7.9 (GS)
dep = 24.4 +/- 2.6
Oh a 7.9 - um no look at the time.
It was this:
* Friday, March 11, 2011 at 05:46:23 UTC
* Friday, March 11, 2011 at 02:46:23 PM at epicenter
Don't forget that this is modern equipment and systems. What chance that data in the 1950+ years makes any sense?
If you are scratching your head don't worry, you are not the only one.
Edit to add: By the way the tone throughout suggests knowledge of the subject, but I doubt it is any greater then mine seeing as they are in the same
line of work as me!!
edit on 19/3/2011 by PuterMan because: (no reason given)