Monday, May 14, 2007

Most of EarthScope seismic stations installed in Arizona: can we make some permanent?

All but a about a dozen of the total 58 stations in the EarthScope
( USArray Transportable Array (TA) of broadband
seismic stations are installed in Arizona at present. A map of the stations was published in "Arizona Geology" last year (

[right: broadband seismic station in New Mexico is similar to those in Arizona. Courtesy EarthScope]

Prof. Matt Fouch at ASU reports that “many of the stations are returning
better data than permanent station installations, and data from the TA
have already been extremely useful in helping constrain crustal thickness
and other regional structure. The TA operations facility has detected
earthquakes and mine blasts at the magnitude 1-2 threshold. It opens up
the issue of potential seismic hazard estimates in other regions of the
state besides the Flagstaff region, which has typically been the only area
with any sort of station coverage. Data from the TA have also already
been extremely useful for helping reform ideas about things like Basin and
Range extension and Colorado Plateau uplift, but the array is still new
enough that we need to wait for more events before we can really make a
fundamental contribution to some of these issues.”

There is now an unanticipated opportunity to keep some of these broadband
seismometers in the state after the array moves east (currently scheduled
to move 12-24 months from now). Oregon and Washington raised $500,000
from private foundations to purchase key TA stations, while Nevada is
seeking a Congressional earmark to acquire stations in that state and have
the USGS maintain them.

There are already 2 stations (at Organ Pipe and Petrified Forest National
Monuments) that the TA plans to leave in the state, and they will operate
and archive the data in near real-time for the next ~10 years. We have
an opportunity to acquire more of these stations and essentially instantly
build a very high-quality seismic network in the state if we can identify
funds to pay for replacement stations as the Array moves eastward.

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