TY - JOUR
T1 - 3-D Modeling of Irregular Volcanic Sources Using Sparsity-Promoting Inversions of Geodetic Data and Boundary Element Method
AU - Zhai, Guang
AU - Shirzaei, Manoochehr
N1 - Funding Information:
The interferograms used in this study are generated using the GMTSAR soft ware (Sandwell et al., 2011). Radar data are provided by the European Space Agency under project C1P-9539 and through the WInSAR archive. The authors would like to thank Paul Lundgren and an anonymous reviewer for the helpful comments that significantly improved the manuscript. We thank Megan Miller for carefully proofreading the manuscript. Great thanks also go to Kaj Johnson for the help with BEM modeling. InSAR time series used in this paper is available as a supporting information file. This research is partly supported by the U.S. Geological Survey grant G13AP00040.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/12
Y1 - 2017/12
N2 - Geodetic observations of surface deformation associated with volcanic activities can be used to constrain volcanic source parameters and their kinematics. Simple analytical models, such as point and spherical sources, are widely used to model deformation data. The inherent nature of oversimplified model geometries makes them unable to explain fine details of surface deformation. Current nonparametric, geometry-free inversion approaches resolve the distributed volume change, assuming it varies smoothly in space, which may detect artificial volume change outside magmatic source regions. To obtain a physically meaningful representation of an irregular volcanic source, we devise a new sparsity-promoting modeling scheme assuming active magma bodies are well-localized melt accumulations, namely, outliers in the background crust. First, surface deformation data are inverted using a hybrid L1- and L2-norm regularization scheme to solve for sparse volume change distributions. Next, a boundary element method is implemented to solve for the displacement discontinuity distribution of the reservoir, which satisfies a uniform pressure boundary condition. The inversion approach is thoroughly validated using benchmark and synthetic tests, of which the results show that source dimension, depth, and shape can be recovered appropriately. We apply this modeling scheme to deformation observed at Kilauea summit for periods of uplift and subsidence leading to and following the 2007 Father's Day event. We find that the magmatic source geometries for these periods are statistically distinct, which may be an indicator that magma is released from isolated compartments due to large differential pressure leading to the rift intrusion.
AB - Geodetic observations of surface deformation associated with volcanic activities can be used to constrain volcanic source parameters and their kinematics. Simple analytical models, such as point and spherical sources, are widely used to model deformation data. The inherent nature of oversimplified model geometries makes them unable to explain fine details of surface deformation. Current nonparametric, geometry-free inversion approaches resolve the distributed volume change, assuming it varies smoothly in space, which may detect artificial volume change outside magmatic source regions. To obtain a physically meaningful representation of an irregular volcanic source, we devise a new sparsity-promoting modeling scheme assuming active magma bodies are well-localized melt accumulations, namely, outliers in the background crust. First, surface deformation data are inverted using a hybrid L1- and L2-norm regularization scheme to solve for sparse volume change distributions. Next, a boundary element method is implemented to solve for the displacement discontinuity distribution of the reservoir, which satisfies a uniform pressure boundary condition. The inversion approach is thoroughly validated using benchmark and synthetic tests, of which the results show that source dimension, depth, and shape can be recovered appropriately. We apply this modeling scheme to deformation observed at Kilauea summit for periods of uplift and subsidence leading to and following the 2007 Father's Day event. We find that the magmatic source geometries for these periods are statistically distinct, which may be an indicator that magma is released from isolated compartments due to large differential pressure leading to the rift intrusion.
KW - InSAR deformation
KW - Kilauea volcano
KW - geodetic inversion
KW - irregular source geometry
KW - magma chamber
KW - sparsity regularization
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U2 - 10.1002/2017JB014991
DO - 10.1002/2017JB014991
M3 - Article
AN - SCOPUS:85038127664
SN - 2169-9313
VL - 122
SP - 10,515-10,537
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 12
ER -