Stephen -

GOOD QUESTION !!!  On September 11, there was a seismic event in Eastern AZ=
,
that prompted telephone calls to the University of Arizona, and was recorde=
d
by several stations including Tucson, AZ Albuquerque, NM and several
Transportable Array (TA) stations in between.  It was not listed on the USG=
S
web site.  I have seen several events over the past few years where I have
recorded something, usually surface waves with indistinct body waves, and
they were not listed.

There is a distinct lack of seismometers south of our border.  There is new
station coming on line in a few months at the tip of Baja California,
Mexico, and another in the Yucatan.  Other than that you have to stick to
the southern US, Puerto Rico, or South America, and South America is very
thin.  I don=B9t know why some events are not listed, but it may have to do
with the lack of sufficient stations for good determination of all their
required data.

If you want to see where all the seismometers in the world are located, I
would suggest that you go to the IRIS web site
http://dmc.iris.washington.edu/     and select software.  Scroll down and
download the GEE program.  It will run on both a MAC and an a PC.  When you
run the program, you can see where the stations are.  Its a fun program to
play with and has many nice capabilities.  If you want you can download
event data from several stations through IRIS, and view the SAC files using
GEE.  I have read in and viewed over 20 stations more than once.  Its a nic=
e
way to start looking at comparing stations and how they record events.
WinQuake will also read SAC files, but it does not read all the header and
you many need to manually reload the event data to get all the functions of
=B3WinQuake to work properly.

You can download events through Wilber II, another nice feature available
through IRIS.  Take a look at their web site, they have a lot to offer.

Another program to consider downloading would be VASE.  It allows you to
specify a station, and a block of time to download data.  These files have
station data, but don=B9t have event data.   However, they can still be read
by WinQuake.

Bob Hancock



On 9/18/07 1:07 PM, "Stephen & Kathy"  wrote:

> Interesting,,   I'm amazed that such a small seismic event could be recor=
ded
> from Alaska to South America, Hawaii to Norway with essentially a constan=
t
> magnitude from Texas to Ohio with the Texas to Ohio time displacement of =
about
> 6 minutes???   And the real mystery,  why isn't it listed???   The
> European-Mediterranean Seismological Centre has a 4.1 automated event lis=
ted
> for Honduras for about the right time, but I can't imagine it would be
> recorded in Hawaii, Alaska and Norway???
>   Stephen
>=20
> Bob Hancock wrote:
>> =20
>> I downloaded data from the TUC receiver (STS-1) for a one hour block 080=
0 to
>> 0900 UTC on September 17 from IRIS through the VASE program.  The Tucson
>> sensor records at 20 SPS.  It most likely is a seismic event; however, i=
t is
>> weak enough that initial P & S waves are indistinct.  The surface waves =
(LQ
>> & LR) were visible at elevated levels for over 4 minutes.
>>=20
>> I have recorded supersonic overflights at my station (west of Tucson) be=
fore
>> and you get two sharp spikes, very close together, and nothing that
>> resembles surface waves.  I normally record at 100 SPS.
>>=20
>> This event was recorded by several sensors from the US Network and displ=
ayed
>> on the ASL heliplots.  The displays from ASL are filtered at 0.02 hz, wh=
ich
>> is a long period display.
>>=20
>> Bob Hancock
>>=20
>>=20
>>=20
>>=20
>> __________________________________________________________
>>=20
>> Public Seismic Network Mailing List (PSN-L)
>>=20
>> To leave this list email PSN-L-REQUEST@.............. with
>> the body of the message (first line only): unsubscribe
>> See http://www.seismicnet.com/maillist.html for more information.
>>=20
>>=20
>>  =20
>=20







 &nbs=
p;  Stephen -



GOOD QUESTION !!!  On September 11, there was a seismic event in Easte=
rn AZ, that prompted telephone calls to the University of Arizona, and was r=
ecorded by several stations including Tucson, AZ Albuquerque, NM and several=
 Transportable Array (TA) stations in between.  It was not listed on th=
e USGS web site.  I have seen several events over the past few years wh=
ere I have recorded something, usually surface waves with indistinct body wa=
ves, and they were not listed.



There is a distinct lack of seismometers south of our border.  There i=
s new station coming on line in a few months at the tip of Baja California, =
Mexico, and another in the Yucatan.  Other than that you have to stick =
to the southern US, Puerto Rico, or South America, and South America is very=
 thin.  I don’t know why some events are not listed, but it may h=
ave to do with the lack of sufficient stations for good determination of all=
 their required data.



If you want to see where all the seismometers in the world are located, I w=
ould suggest that you go to the IRIS web site    http://dmc.iris.washington.edu/  &nbs=
p;  and select software.  Scroll down and download the GEE pr=
ogram.  It will run on both a MAC and an a PC.  When you run the p=
rogram, you can see where the stations are.  Its a fun program to play =
with and has many nice capabilities.  If you want you can download even=
t data from several stations through IRIS, and view the SAC files using GEE.=
  I have read in and viewed over 20 stations more than once.  Its =
a nice way to start looking at comparing stations and how they record events=
..  WinQuake will also read SAC files, but it does not read all the head=
er and you many need to manually reload the event data to get all the functi=
ons of “WinQuake to work properly.



You can download events through Wilber II, another nice feature available t=
hrough IRIS.  Take a look at their web site, they have a lot to offer.<=
BR>


Another program to consider downloading would be VASE.  It allows you =
to specify a station, and a block of time to download data.  These file=
s have station data, but don’t have event data.   However, t=
hey can still be read by WinQuake.



Bob Hancock







On 9/18/07 1:07 PM, "Stephen & Kathy" <skmort@.............
> wrote:



<=
SPAN STYLE=3D'font-size:14.0px'>Interesting,,   I'm amazed that such=
 a small seismic event could be recorded from Alaska to South America, Hawai=
i to Norway with essentially a constant magnitude from Texas to Ohio with th=
e Texas to Ohio time displacement of about 6 minutes???   And the =
real mystery,  why isn't it listed???   The European-Mediterr=
anean Seismological Centre has a 4.1 automated event listed for Honduras for=
 about the right time, but I can't imagine it would be recorded in Hawaii, A=
laska and Norway???

  Stephen



Bob Hancock wrote: 

 

I downloaded data from the TUC receiver (STS-1) for a one hour block 0800 t=
o

0900 UTC on September 17 from IRIS through the VASE program.  The Tucs=
on

sensor records at 20 SPS.  It most likely is a seismic event; however,=
 it is

weak enough that initial P & S waves are indistinct.  The surface =
waves (LQ

& LR) were visible at elevated levels for over 4 minutes.



I have recorded supersonic overflights at my station (west of Tucson) befor=
e

and you get two sharp spikes, very close together, and nothing that

resembles surface waves.  I normally record at 100 SPS.



This event was recorded by several sensors from the US Network and displaye=
d

on the ASL heliplots.  The displays from ASL are filtered at 0.02 hz, =
which

is a long period display.



Bob Hancock









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