Magnetotelluric (MT) is a geophysical exploration method to probe the Earth´s deep interior for its electrical conductivity distribution. The MT set-up consists of long-period fluxgate magnetometers and non-polarizing electrodes to measure the electromagnetic field at the surface of the earth. Earth´s response to electromagnetic induction is given by the ratio of time varying horizontal magnetic and electric fields.
Within the framework of the Integrated Plate Boundary Observatory Chile MT is used to monitor and analyze electromagnetic data at seven observation sites to decipher possible changes in the subsurface resistivity structure, e.g. as a consequence of large scale fluid relocation associated with subduction zone related, dynamic processes. Already small amounts of brines (in interconnected veins) can suffice to significantly increase the bulk conductivity of a rock or an entire region of the subsurface. MT measurements are made at eleven of the multi-parameter sites (details can be found here).
An overview over all sites of IPOC and details about the respective stations can be found here.
The magentotellucic data of IPOC is available upon request. Please contact Oliver Ritter for further information.
People involved: Oliver Ritter, Ute Weckmann, Jaime Araya (PUC)
Partner Institutions: GFZ German Research Centre for Geosciences, Pontificia Universidad Católica de Chile (PUC), Universidad Católica del Norte (UCN)
Araya Vargas, Jaime, Large-scale distribution of fluids in the subduction zone of Northern Chile - constraints from magnetotelluric monitoring, Dissertation, Freie Universität Berlin 14. Juli 2016, www.diss.fu-berlin.de/diss/receive/FUDISS_thesis_000000102666
Araya Vargas, J., and O. Ritter (2015), Source effects in mid-latitude geomagnetic transfer functions, Geophysical Journal International, 204(1), 606-630, doi.org/10.1093/gji/ggv474
Brändlein, D. (2013) Geo-electromagnetic monitoring of the Andean Subduction Zone in Northern Chile. PhD Thesis, Berlin: Freie Universität, www.diss.fu-berlin.de/diss/receive/FUDISS_thesis_000000094658
Brändlein, D., H. Lühr, and O. Ritter (2012), Direct penetration of the interplanetary electric field to low geomagnetic latitudes and its effect on magnetotelluric sounding, Journal of Geophysical Research: Space Physics, 117(A11), n/a-n/a, doi.org/10.1029/2012ja018008