PSN-L Email List Message

Subject: [Fwd: CNSS Update (San Jose Array)]
From: Edward Cranswick cranswick@........
Date: Mon, 20 Mar 2000 20:44:19 -0700




--
Edward Cranswick                Tel: 303-273-8609
US Geological Survey, MS 966    Fax: 303-273-8600
PO Box 25046, Federal Center    cranswick@........
Denver, CO 80225-0046  USA      E.M. Forster said, "Only connect".

Jim-
    As far as I know and from what Art Frankel says in his page of explanation
on the website , the
waveforms are acceleration recorded by the internal K2 FBAs and then
band-passed at 0.125 - 0.25 Hz (4.0-8.0 s period) -- they have not been
integrated. Only at these long wavelengths is the wave propagation coherent
across the array, given the inter-element spacing of 1.0 km (which is large or
small alternately, depending upon whether one is researching high-frequency
seismology or paying for the hardware and installation). Though this seems
quite a low frequency band, we coincidently saw a strong site response in
Avcilar, Turkey at these frequencies that seems to be responsible for
significant damage to 4-6-story reinforced concrete apartment buildings
.

    With respect to your abstract (part of which I quote below),

"DOE technical reports in the early 1970ís, were the first to describe the
anomalous high shaking that occurs in parts of the Las Vegas Valley from
seismic waves, generated from underground nuclear tests.  A more recent
publication (1998), by UNR Seismological Laboratory seismologists, determined
the anomalous site amplification (anomalous shaking) for the Las Vegas Basin is
even higher than previously reported. They analyzed DOE seismic strong motion
data recorded in Las Vegas from the 1992, Little Skull Mountain earthquake,
M5.6."

though I participated in our aftershock investigation of the Little Skull
Mountain Earthquake at NTS, I am not familiar with the work done in Las Vegas.
I am sure that virtually anywhere one monitors a basin with sufficient density
of seismic stations, one will finf "anomalous shaking".
-Edward

Jim ODonnell wrote:

> Hi Ed- I just finished downloading the SJ Array movie, it took 50min's as
> it is almost 8Mb, but it was really outstanding!!!  Could you tell us
> what seismometer is being used, as the K2, I gather, is only a digital
> recorder from Kinemetrics.  The data looks like it is in velocity, so I
> am assuming you used a strong motion accelerometer and then integrated
> but please fill us in on that.

--
Edward Cranswick                Tel: 303-273-8609
US Geological Survey, MS 966    Fax: 303-273-8600
PO Box 25046, Federal Center    cranswick@........
Denver, CO 80225-0046  USA      E.M. Forster said, "Only connect".



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Larry Cochrane <cochrane@..............>