EMSCOPE News:
Current Headlines
March 2009-
The MT TA instrument pool has been reconditioned and is ready for field operations. A subcontract has been awarded to the University of Utah to acquire at least 50 MT TA stations in Wyoming and Montana, contiguous with the 2006-2008 MT TA arrays in Cascadia and the Snake River Plain region. A new interface to the MT TA instruments has been released by Oregon State University, providing a modern graphical user interface with real-time graphical data displays, local as well as remote data logging and telemetry back-office support.
November 2008-
A complete set of MT response functions for all 170 MT TA stations has been uploaded to the IRIS DMC including improved responses for sites previously uploaded.
October 2008-
50 new MT TA stations have been successful acquired under the operational direction of the University of Utah, bringing the total number of MT TA stations from the start of the Earthscope project to 170.
September 2008-
The MT Backbone network has been completed by Oregon State University, with final installations completed at Braden Missouri, Socorro New Mexico, and Parkfield California.
August 2008-
MT Backbone stations have been sited, permitted and completed at Angela near Miles City Montana, and in the Agassiz National Wildlife Refuge near Thief River Falls Minnesota.
June 2008-
The 2008 MT Transportable Array experiment has commenced, with first station installed in northern Utah on 6/3/08 by a team of students from Virginia Tech and Texas A&M, under the direction of the University of Utah.
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News Archive
December 2007-
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(1)Initial results of first 3-D inversion of combined Oregon Pilot Project (2006) and Cascadia (2007) MT TA experiments presented at Fall AGU meeting in San Francisco by Patro et al showing sensitivity of MT TA array to Basin and Range conductor, a proposed conductive pathway from the Oregon and Washington coast region into the mantle, a resistive Cascade front, the British Columbia and SWCC conductive zones.
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(2)New MT Backbone Site selected and permitted. Site MTB06 has been permitted at Virginia Tech’s Kentland Farm in Blacksburg, Virginia. Six out of seven MT Backbone sites have now been either permitted or installed.
November 2007-
(1) MT Transportable Array. Following a successful 30-station pilot experiment in western Oregon in 2006, EMScope/IRIS contracted with Geosystems USA (GSY) to continue their work in 2007. By the end of October 2007, GSY completed an 80-station MT transportable array deployment in Western Oregon, in Washington State and in Idaho, with one station in northern California. This work concludes the Cascadia component of MT TA operations for EarthScope. It is anticipated that an approx 50-60 station MT TA deployment will take place in the greater Yellowstone region in spring-summer 2008.
(2) MT Backbone Array. Four of seven major infrastructure installations for MT BB are now complete, including sites MTB01 in Parkfield, California; MTB02 at Soap Creek, Oregon; MTB03 in Braden, Missouri; MTB04 in Socorro, New Mexico. Siting and permitting has been completed for a fifth MT BB station, at the LASA station in north-eastern Montana. Siting and permitting has begun in Virginia at two candidate sites, one at Fredericksburg at the USGS/NOAA facility attached to the permanent magnetic observatory, and another near Blacksburg. Another MT BB installation is anticipated for Wisconsin or Michigan.
(3) - Instrumentation status. As of Spring 2007, all NIMS (Narod Intelligent Magnetotelluric System) instruments ordered for EMScope have arrived and been through acceptance testing by Oregon State University. The fleet is composed of 20 portable NIMS units packed in pelican cases and small cylindrical sensor housings, for MT transportable array operations, and 7 specially-designed NIMS packaged in larger cylindrical housings designed specifically for insertion into EMScope Backbone instrument vaults. A LEMI MT system produced by the Space Research Institute of Ukraine has been acquired, as a spare unit, and to test for suitability for future adoption by the US MT community.
(4) Data status. All data acquired to-date has been transmitted to the IRIS DMC and is available for download.
(5) New management plan adopted. IRIS has contracted with Oregon State University to provide overall management of EMScope, as well as to provide data services (QC, generation of MT response functions, transmission of data and data products to IRIS DMC), instrument center functions (maintenance, depot activities), oversight of MT transportable array operations and maintenance, and direct responsibility for MT backbone operations and maintenance.
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.
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 Transportable 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.
