EGU2020-6188
https://doi.org/10.5194/egusphere-egu2020-6188
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Resistivity model for the Colima Volcanic Complex from magnetotelluric observations

Héctor Manuel Romo Lozano and Jorge Arturo Arzate Flores
Héctor Manuel Romo Lozano and Jorge Arturo Arzate Flores
  • Universidad Nacional Autónoma de México, Centro de Geociencias, Querétaro, Mexico (hromolozano@geociencias.unam.mx)

The Colima Volcanic Complex is located within the central portion of the Colima Rift in the occidental part of Mexico. This volcanic structure is composed of two stratovolcanoes; the extinct Nevado de Colima and Volcán de Fuego. The latter is considered the most active volcano in the country which volcanism is related to the subduction of two oceanic plates with different slab angles that cause a gap between them just beneath the complex. Different methodologies have been carried out in this zone; seismic tomography and potential field data modelling to constraint a geophysical model that contributes the better understanding of the magmatic system and the geothermal energy potential.

 To reduce non-uniqueness of the previous models, a campaign was realized in September 2019 where 10 broadband magnetotelluric soundings were acquired and further process and inversion in conjunction with previous data was done. The distortion analysis for the data set presented a 1D behavior for the first kilometers and 2D and 3D behavior at higher depths suggesting the need of a 2D or 3D approach for the inversion. The electric strike calculation suggests the rotation of the impedance tensor so that the non-linear conjugated gradients algorithm of Rodi & Mackie (2001) was applied along three profiles perpendicular to the principal structures to obtain 2D resistivity models.

The inversion results range from 3.4 to 5.6 RMS error and show for all the profiles good correlation for the surface lithology, the principal normal faults which define the graben structures filled with pyroclastic deposits and alluvial sediments and a high resistive basement. For major depths, the northern profile shows a vertical extensive conductive body which connect to an upper conductive layer. So do the central profile, south the Volcán de Fuego vent but the superficial body is more conductive which can correlate with previous models as a magma reservoir approximately at a 2 km depth.

 

How to cite: Romo Lozano, H. M. and Arzate Flores, J. A.: Resistivity model for the Colima Volcanic Complex from magnetotelluric observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6188, https://doi.org/10.5194/egusphere-egu2020-6188, 2020

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Presentation version 2 – uploaded on 03 May 2020
  • CC1: Comment on EGU2020-6188, David Martínez van Dorth, 04 May 2020

    Hello!

    First of all, what an amazing work! I really like the correlation with the seismic models.

    I just have a question. In order to obtain information of greater depths, which range of frequency did you use and for how long did you installed the equipment?

     

    Best regards,

    David MvD.

  • CC2: Comment on EGU2020-6188, Jorge Arzate, 04 May 2020

    Hola David,

    Los equipos MT de banda ancha registran por 18-24 horas y el de periodo largo (LMT)

    estuvo registrando por más de 4 semanas. Pero en general el rango de frecuencias EM utilizado

    en el artículo está entre 1,000 y 0.001 Hz...

Presentation version 1 – uploaded on 03 May 2020 , no comments