EMSCOPE MT Transportable Array Stations

MT Backbone (MT TA) array consist of a set of 20 portable Narod NIMS magnetotelluric data acquisition systems sampling at 1 Hz. The systems are installed at each site for periods of less than one month, and are then relocated to the next site. A regular 70 km x 70 km grid of sites is occupied during each field season, defining a set of large-scale targeted geotraverses across the continental USA. The first MT TA pilot experiment occupied 30 sites in eastern Oregon in 2006. This was followed by 80 sites in western Oregon, in Washington State, in western Idaho, and the NW tip of California in 2007, which concluded the Cascadia Geotraverse. In 2008 the array was extended east along the Snake River Plain and adjoining areas, approaching the borders of Yellowstone. In 2009 the array will continue eastward, through Yellowstone and the Grand Tetons. A community-wide planning meeting was held in June 2008 to determine the location of future geotraverses.

(click on figure below to open detailed 1.3 MB JPG file)

The orange circular symbols in the figure above are the 170 MT TA stations acquired in 2006-2008. the white triangles are a set of stations obtained by the University of Alberta in coordination with and using a continuation of the same grid as EMScope. The sun-shaped symbols are pre-EMScope stations acquired by C. deGroot-Hedlin and included in the IRIS DMC. The small blue boxes with white crosses are USGS MT stations also appearing in the IRIS DMC. The large orange crosses at MT Backbone stations, and the red satellite dish symbols are permanent magnetic observatories.

The TA NIMS instruments are housed in compact Pelican(tm) cases. Five TA NIMS are seen in the background of the photo below. The short gray cylinders behind the cases is the housing for the triaxial ring core fluxgate magnetometer sensor.

The three photos following are scenes of the MT TA student field crew setting up site IDL16 in Idaho, summer 2008.

In addition to quality-controlled MT time series, the primary derived data products available for unrestricted download are MT response functions. Two examples are seen directly below, one for Idaho showing the effects of a crustal conductor beneath the Snake River Plain (left) and another from the Plains of Montana (right), where such a feature is not evident.