EGU21-467
https://doi.org/10.5194/egusphere-egu21-467
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Application of deformation–induced topographic effect in interpretation of 2013–2016 spatiotemporal gravity changes at Laguna del Maule (Chile)

Peter Vajda1, Pavol Zahorec1, Craig A. Miller2, Hélène Le Mével3, Juraj Papčo4, and Antonio G. Camacho5
Peter Vajda et al.
  • 1Earth Science Institute, Slovak Academy of Sciences, Dubravsku cesta 9, P.O.Box 106, SK-840 05, Bratislava, Slovakia
  • 2GNS Science, Wairakei Research Center, Private Bag 2000, Taupō 3330, New Zealand
  • 3Carnegie Institution for Science, Earth and Planets Laboratory, 5241 Broad Branch Road NW, Washington, DC 20015, USA
  • 4Dept. of Theoretical Geodesy, Slovak University of Technology, Radlinskeho 11, SK-810 05 Bratislava 15, Slovakia
  • 5Institute of Geosciences (CSIC-UCM), C/Doctor Severo Ochoa, 7, Ciudad Universitaria, 28040, Madrid, Spain

The accurate deformation-induced topographic effect (DITE) should be used to account for the gravitational effect of surface deformation when analyzing residual spatiotemporal (time-lapse) gravity changes in volcano gravimetric or 4D micro-gravimetric studies, in general. Numerical realization of DITE requires the deformation field available in grid form. We compute the accurate DITE correction for gravity changes observed at the Laguna del Maule volcanic field in Chile over three nearly annual periods spanning 2013–2016 and compare it numerically with the previously used free-air effect (FAE) correction. We assess the impact of replacing the FAE by DITE on the model source parameters of analytic inversion solutions and apply a new inversion approach based on model exploration and growing source bodies. The new inversion results based on the DITE correction shift the position of the mass intrusion upwards by a few hundred meters and lower the total mass of the migrated fluids to roughly a half, compared to the inversion results based on the local-FAE correction. Our new Growth inversion results indicate that vertical dip-slip faults beneath the lake, as well as the Troncoso fault play active roles in hosting migrating liquid. We also show that for the study period, the DITE at Laguna del Maule can be accurately evaluated by the planar Bouguer approximation, which only requires the availability of elevation changes at gravity network benchmarks. We hypothesize that this finding may be generalized to all volcanic areas with flatter or less rugged terrain and may alter interpretations based on the commonly used FAE corrections.

How to cite: Vajda, P., Zahorec, P., Miller, C. A., Le Mével, H., Papčo, J., and Camacho, A. G.: Application of deformation–induced topographic effect in interpretation of 2013–2016 spatiotemporal gravity changes at Laguna del Maule (Chile), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-467, https://doi.org/10.5194/egusphere-egu21-467, 2021.

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