Robinesque Ruminations, page 21

reply to post by ericblair4891

Hello Eric,

my first feeling also was that this Montana quake is pretty normal. The region has a fair bit of seismicity, historically. That first feeling was just as I considered that one quake in isolation.

However, my second feeling, which followed a few seconds later, was that I have rarely seen so many quakes showing on the Nth America/US maps in such a wide diversity of places, and that bothers me. And that led me back to that particular quake.

I need to check how often they get quakes around that magnitude or bigger in that region. Must do a search of a database.

EDIT: ok, did the search in the NEIC database from Jan 1, 1973 to Nov 10, 2011 for quakes mag 4.0 or bigger within 160 km (100 miles) of the Montana quake's epicenter at 46.62°N, 113.56°W (rounded to 2 digits) and got the following:

NEIC: Earthquake Search Results

U. S. G E O L O G I C A L S U R V E Y

E A R T H Q U A K E D A T A B A S E

FILE CREATED: Sat Nov 12 16:42:23 2011
Circle Search Earthquakes= 18
Circle Center Point Latitude: 46.620N Longitude: 113.560W
Radius: 160.000 km
Catalog Used: PDE
Date Range: 1973/01/01 to 2011/11/10
Magnitude Range: 4.0 - 10.0
Data Selection: Historical & Preliminary Data

CAT YR MO DA ORIG TIME LAT LON DEP MAG IEM DTSVNWG DIST
......................................................................................NFO....................km
.......................................................................................TF

PDE 1975 01 17 041856.10 47.44 -114.35 5 4.4 mbGS .F. ........ 109
PDE 1978 04 23 232437 46.97 -113.27 5 4.9 MLGS 5F. .......... 44
PDE 1978 11 10 095345.60 47.01 -113.33 5 4.3 MLGS 5F. ........ 46
PDE 1979 06 22 120226.80 45.32 -112.83 5 4.4 MLGS 5F. ....... 154
PDE 1980 03 10 144856.50 47.30 -113.39 5 4.4 MLGS 4F. ........ 77
PDE 1983 03 17 072556.69 47.53 -112.70 5 4.2 mbGS 5F. ....... 119
PDE 1985 04 01 091314.21 47.28 -113.23 10 4.8 mbGS 6D. ....... 77
PDE 1987 07 23 015257.76 47.72 -113.67 5 4.2 MLBUT 5F. ....... 122
PDE 1990 11 30 113048.37 47.77 -113.16 5 4.0 MLBUT ... .......... 131
PDE 1992 03 21 015743.01 47.29 -113.27 5 4.1 MDBUT 4F. ........ 77
PDE 1992 04 01 113347.71 47.88 -113.73 5 4.2 MLBUT 3F. ....... 141
PDE 1998 04 15 022835.45 48.01 -113.75 4 4.1 MDBUT .F. ....... 154
PDE 1998 10 28 031154.41 45.70 -112.13 5 4.1 MDBUT .F. ....... 150
PDE 2000 06 28 142831.90 46.62 -113.54 9 4.5 MLGS .F. .......... 1
PDE 2002 07 19 195826 47.43 -113.05 24 4.0 MLBUT .F. .......... 98
PDE 2005 07 26 040837.16 45.37 -112.61 12 5.6 MwHRV 6DM .... 157
PDE 2005 07 27 155145.85 45.38 -112.60 5 4.0 MwSLM 4FM ....... 156
PDE 2009 03 06 112954.50 45.70 -112.13 11 4.0 mbGS 4F. ....... 150

Source: NEIC Quake Database Search Results

There have been just 18 quakes of mag 4.0 or bigger within that defined region in the past 38 years. One every two years or so, on average. And of that set, there have been only 11 equal to or larger than the Friday 11/11 event. (ie, about one every three years or so.) Few have been real close to that spot; the last one almost bang on the same location (and in fact within 1 km) was back on 28 June, 2000.

So, such quakes are pretty uncommon there.

Note, however, that there was a mag 5.6 Mw about 95 miles (157) from that location on 26 July, 2005. So, even if we see more quakes and they get up into that kind of magnitude range it doesn't have to indicate anything more massive is impending. It might, but doesn't have to.

But if scoffers (or paid disinfo agents

) pass the comment, "Oh, a mag 4.2 in that part of Montana? Hey, they get them all the time so it's no big deal. You people need to get a life, etc etc," then you can tell them they're wrong. Once every three years is not "all the time".

And point them to this post or the linky supplied, which will confirm that what I've posted is what a well-respected and official data base says.

Mike

edit on 12/11/11 by JustMike because: I would hope it's obvious.