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Data assimilation in volcanic deformation

Shungo Tonoyama 1, Atsushi Suzuki 2, Kengo Nakajima 2,3, Takemasa Miyoshi 1

  • Affiliations: 1Data Assimilation Research Team, RIKEN Center for Computational Science, RIKEN, Hyogo, Japan; 2Large-scale Parallel Numerical Computing Technology Research Team, RIKEN Center for Computational Science, RIKEN, Hyogo Japan; 3The University of Tokyo, Tokyo, Japan 

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 269

  • Programme No: 2.4.41

  • Theme 2 > Session 4

Abstract

Data assimilation combines numerical modelling and observational data and is now being applied across various fields in Earth sciences. Here, we propose new data assimilation methods for volcanic eruptions. We developed an elastic deformation model based on the finite element method and carried out identical twin experiments. Data assimilation experiments were performed by applying the Kalman filter and the adjoint method. The surface displacements from the true model were perturbed with independent Gaussian random noise to represent the actual observation data estimated by time-series Interferometric Synthetic Aperture Radar (InSAR) analysis. By assimilating the ground deformation data, the state of the magma chamber was estimated. In the Kalman filter experiment, a magma chamber initially placed at a location different from the true location was sequentially adjusted by data assimilation. The results show that the magma chamber depth analysis converged to the true state by assimilating data for eight steps (equivalent to two months) likely because the depth direction has a significant impact on ground deformation observation. In the adjoint method, the surface stress field of the magma chamber is estimated by minimizing the difference between the observed and model-predicted surface displacements. Here, the goal is to accurately determine the surface stress field of the magma chamber, assuming its location and size are known. The results showed convergence after approximately 50 iterations, successfully reproducing the target stress field.