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Current News-

Braden Missouri Backbone Station (MTB03a) Installed in June 2006

The third permanent Backbone magnetotelluric station for USArray was installed by the Oregon State University BB MT team (A. Schultz and P. Taylor), with the assistance of Missouri State University (K. Mickus and M. Gutierrez). The site is near Sparta Missouri, SE of Springfield, and includes a 300 m long E-W electric dipole, and 230 m long N-S electric dipole, and two 6' deep vaults for magnetometer sensor head and NIMS data acquisition unit. The electrode installation follows the procedures established in Parkfield at site MTB01a. An MT time series was acquired from the site to confirm acceptability for full operations. When vendor instrumentation for BB MT has been delivered, this will be installed at MTB03a.

A vendor has been selected to carry out the Oregon Pilot Transportable Array experiment, as of June 2006

The first field program for MT Transportable Array comprises a 30-50 station array covering much of the territory of Oregon. A request for bids was answered with six responses, and negotiations are underway with the winning bidder. It is anticipated that the TA pilot experiment will commence field operations in July 2006.

Archived News-

Seismic-Magnetotelluric instrumentation interaction and electrode comparison test, May 2006

Three MT stations were installed at Soap Creek Ranch, Oregon, near Corvallis by the Oregon State University BB team, to evaluate the potential for interactions between these different geophysical instruments at differing distances. This was necessary to determine if seismic Transportable Array and magnetotelluric Transportable Array stations could share the same site. Simultaneously, an experiment was conducted to determine the optimcal chemistry for very long period megnetotelluric electrodes, for the Backbone MT program. The tests were completed in June 2006, and a set of electrodes has been left in place to study the change in contact resistance with time over the summer of 2006. The site has been selected, provisionally, as a Backbone station, with the designation MTB02a.

Parkfield Site Installed, May 2006

The first EMSCOPE Backbone station was installed at the "Hunt" site near Parkfield California by the Oregon State University BB team (A. Schultz and P. Taylor) with the assitance of S. Park of University of California, Riverside, and C. Park of Bishop, California. Thhe installation includes two 2-meter deep vaults to contain the magnetometer and data acqusition units, and a cross-shaped array of 100 meter long electric field receiver dipoles, terminated in a newly designed set of Pb-PbCl2/kaolin-NaCl-H2O electrodes, each of which is stored in a sealed casing containing 2 liters of kaoline-NaCl-H2O with open ports into a "Russian bucket", also filled with salt-saturated kaolin, stored in the bottom of a 1-m deep partially cased hole. This provides good electrical coupling between the electrode and the Earth, but slows the exchange of electrolyte with the surrounding soil, and keeps the electrode moist in close-to-isothermal conditions for extended periods of time. This thermal and chemical stability will assist in long-term unattended operations capable of delivering stable long-period electric field data, suitable for probing the electrical structure deep into the Earth's mantle. This newly installed site, designated MTB01a is near the long-established Carr Hill site where the Univ. of California Riverside has obtained 18 years of electric field data from long, leased telephone cables. MT data were acquired from this stie to validate it for long-term operations. When vendor instrumentation for BB MT has been delivered, this will be installed at this location. This site has been taken over by EMSCOPE, and is designated MTB01b.

Vendor Selection - MT equipment vendor selected, September 2005

A vendor has been selected to provide emscope with the long-period MT instrumentation specified in an RFQ issued previously this year. Delivery schedules are presently being negotiated. Details will be released in the near future.

Updated Backbone Candidate Site list, September 2005

A revised list of Candidate MT Backbone sites has been assembled following lengthy consultations with IRIS, with USGS (seismic and geomagnetic divisions), and after seeking input from the US magnetotelluric community through establishment of the emscope web site, blog, and mass mailings through the MTNet portal. The revised candidate list may be seen by linking to the "MT Backbone Site Map" menu on the left-hand-side of this screen. This is subject to further changes as additional information becomes available. Site metadata is being input, and appears by clicking on the various hotspots indicated on the map. Site visits will commence 4th qtr 2005.

RFQ responses - MT equipment vendor trials near Bishop California, April 2005

A series of potential vendors have responded to the RFQ issued by IRIS for providing magnetotelluric instrumentation for MT Backbone and MT Bigfoot arrays. The RFQ may be viewed here.

On 30 April-1 May, a team from University of California, Riverside, Oregon State University, IRIS and USGS (members of an IRIS advisory body involved in the instrumentation procurement oversight committee) will be installing candidate instruments at a field station near Bishop, California. The instrumentation will be operated for a number of weeks, following which a data reduction exercise will be carried out to evaluate the noise specifications and instrument performance under realistic field conditions. Performance, meeting stated specifications, cost, availability, servicing will all be factors in evaluating the competing bids. The final selection of vendor is expected by the end of the first half of 2005.

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Last update 6/16/06