PSN-L Email List Message
Subject: Re: seismic records
From: Bob Hancock carpediem1@.........
Date: Sat, 12 Jul 2008 10:57:41 -0700
I don't believe there is a database of mine blasting, and construction
events. One of the problems with low magnitude events is the wave amplitude
which decreases with distance. The other thing is that initial movement on
a P wave will be the same regardless of the quadrant you are in. That is
how underground nuclear testing is detected. The nuclear bomb testing that
was conducted by North Korea was picked up on Chinese seismograms, and the
USGS had a link to the data. We have lots of open pit copper mining here in
Southern Arizona, and quite often I see the surface wave, but may loose the
P & S waves in the background.
You can use the use the USGS program for phase timing, see link:
Or its sister program which only has events from the last 14 days:
Both programs have wave amplitude information which may give you some idea
of what events you can see from whatever distance. I use them all the time
to check on the phase travel times.
Another program you can download from IRIS is VASE, see link:
This program will allow you to download data from various seismic stations
that have recorded data in the IRIS database. You select the network,
station, channels and time you want, and the format (SAC Binary). I have
used this to check out undocumented events. One advantage of the vase
program is that you can download several hours of data at one time. If you
wanted to search a block of data with this program its possible. Again, you
have to specify a date and time. Its a JAVA based program, and probably not
suitable for a dial-up connection.
On comment about mine blasts. Here in Southern Arizona, they frequently use
ripple blasting which is a series of individual blasts over a specified
distance in quick sequence, such as one or two seconds. You can often see
the initial P wave clearly, if its close enough, but after that the
seismogram gets very muddy trying to pick out everything else. I am unaware
(they are probably here) of any tunnel mining in Southern Arizona, and the
single blasts typical of that type of mining.
On 7/12/08 10:10 AM, "Thomas Dick" wrote:
> Bob, your comments put a lot of good information in one place. I are having
> a lot of mine blasting, construction and earthquakes less than 3 in this
> area. They aren't found as data files on Wilber -- or I don't know how to
> find them. I wanted to do some triangulation. There also seems to be some
> minor ducting going on ... blasting seems stronger than it really is. Might
> even try some fossil hunting later in the Fall if I can afford the gasoline.
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