"EarthScope MT - A Shocking..."
EarthScope MT - A Shocking Science
Shane Ingate
EarthScope USArray MT Manager
USAAC
May 16, 2006

What is MT?
The objective of MT is to monitor time-variations of conductivity associated with deep mantle processes.
MT yields information about:
Structures
Presence of fluids and/or conductors
Imaging the electrical conductivity gives information about the subsurface that can give insight into formation, deformation, and active processes

MT measures electrical conductivity
Fizziks
Amperes law for magnetic fields
GaussÕ Law for electric field
Faradays Law
MaxwellÕs Law

MT Hardware
More Fizziks
Experience with depth vs. recording time
Natural EM waves I
Natural EM waves II
Natural EM waves III
MT Data
MT & Seismic Data
Mb 5.1 San Juan Bautista, CA, 8/12/98
10 sec of MT & seismic data
Seismic are 1 Hz & 80 Hz
MT is sensitive to ground motion; surface waves displace electric dipole cables and induction coils
MT similarly effected by wind, cultural noise, etc

2-D Inversion
EarthScope MT
7 permanent MT installations, coincident with ANSS backbone stations - Goal: deep mantle
20 MT installations that go with the TA (1 month in place at a time) - Goal: mid-upper mantle
EMSOC MT stations available for short-term loans for PI-driven campaign research, as funding allows - Goal: lower lithosphere and crust

ES MT Structure
A USArray Magnetotelluric Manager (Shane Ingate) will be responsible for coordination of MT activities and oversight of the portable MT program. The MT Manager will report to the IRIS President as PI for USArray.
A Magnetotelluric Working Group will be established to provide advice to the MT Manager. This working group will be constituted under and report to the IRIS Coordinating Committee.

ElectroMagnetic Working Group (EMWoG)
Members
Gary Egbert (OSU)
Rob Evans (WHOI)
Shane Ingate (IRIS) - Liason
Dean Livelybrooks (UO)
Kevin Mickus (Miss State)
Stephen Park (UCR)
Adam Schultz (OSU)
Martyn Unsworth (U. Alberta)
Phil Wannamaker (UU) - Chair
Observers
Tim Ahern (IRIS)
Kent Anderson (IRIS)
Bob Busby (IRIS)
Jim Fowler (IRIS)

EMWoG Tasks
USArray Change Order #15
Web site
Equipment selection (pre-EMWoG)
Backbone planning
Legacy Sites
Cooperation with POLARIS
Oregon pilot project
Outreach (1-pagers)
EOS paper
Future planning

MT Procurement Status
Procurement
Order for 20 NIMS systems placed Nov Ô05
Order revised Apr 06
ETA Autumn, Ô06
Order for 7 NIMS systems placed Apr Ô06
ETA Spring, Ô07
Order total CAD$412,793 (~$363K)
Concern: Availability of suitable ring core material (5/12/06 run failed)

Backbone MT - status
Backbone Schedule
4/30-5/5 ANMO, NM (now Hilton Ranch)
5/19-5/23 Parkfield, CA
6/5-6/9 Bull Shoals, MO
6/22-6/25 Wild Horse Valley, OR (now Soap Creek)
7/9-7/14 Conover (COWI), WI
8/27-9/1 Alum Ck State Park (ACSO), OH
9/17-9/22 Dagmar (DGMT), MT
10/15-10/27 Visit any alternative Backbone sites required
11/12-11/25 Acceptance testing newly delivered Backbone NIMS
(Note: 2 systems for Backbone testing on loan from EMSOC)

Transportable MT - Status
Transportable MT - OR Pilot
TA Co-location MT.SPC02 and TA.H03A
Tests conducted at TA.H03A 8-12 May to determine influence of passive MT recording systems on TA equipment, and impact of TA telemetry and large mass/coil movements on MT.

SPC02/H03A - Interactions
SPC02/03 - Electrode test
Legacy Experiments
Transportable Planning
GeoFrame workshop listed priority areas for Flex Array studies.
Cascadia/Idaho bath/Yellowstone/maybe Black Hills
Salton Sea/Walker Lane
Mid Continent Rift/Superior area
S. Appalachians/New Madrid/Reelfoot Rift.
These areas will have to get broader community support through the proposal process but they may be tentative choices for MT groups of 70 km sites.

Fin
SIG