Purpose

The tool for automatic modeling is capable of autonomously performing both non-linear and linear inversion sequences to determine the slip distribution of a seismic event. In its current implementation, the automatic modeler can accept an arbitrary number of InSAR datasets as input, which are modeled using a single Okada source.

Technical Note

The initialization of the procedure is based on the focal mechanism of the event, which can be retrieved via the "Find a focal mechanism" button that accesses three alternative catalogs online: USGS, Global CMT, and INGV. The spatial and temporal search intervals for the event are automatically set based on the coverage of the InSAR datasets and the acquisition times of the interferometric pairs (the magnitude range must be set manually). If multiple events meet the search criteria, the user can select the reference event from a list.

The automatic modeler performs non-linear inversion to find the source geometry with uniform slip, determining the best-fit parameters or fixing parameters that cannot be constrained by the data; the algorithm can identify point-source conditions, apply topographic corrections, and determine the weights to assign to the InSAR datasets. For each InSAR dataset, offset, ramp (default) or a quadratic surface can be estimated. If the non-linear inversion is successful, linear inversion is performed to find the slip distribution. During the linear inversion, the system also determines the optimal damping factor. The automatic processing is created within a dedicated directory where, in addition to the results, project XML files are generated and can be used to analyze the results via the standard interfaces of Sarscape for both non-linear and linear inversions.

The entire automatic modeling process can take a long time, depending on the quantity and quality of the input InSAR data. The algorithms that compose the automatic inversion procedure are described in Atzori et al. (2023).

Notes:

•Run the Sampling Area and Image Subsampling tools before running this tool.

•The automatic coseismic inversion searches for the distributed slip source of an earthquake on a single fault plane. For more complex configurations, an ordinary manual inversion is required.

•The duration of the processing heavily depends on the quantity and quality of the input data (including the focal mechanism automatically found in catalogs) and ranges from a few minutes to over an hour.

•When inverting a single InSAR dataset, it is recommended to estimate an offset rather than a ramp (default)

Input

ADD DATASETS

Add from file…: Add a geodetic (InSAR or GPS) dataset from shapefile.

From XML Project File…: Retrieve a dataset from an already existing XML Project File.

Note: The ADD DATASETS button become available only if the Automatic inversion folder is selected.

EDIT DATASETS

Edit parameters…: Set the dataset properties with the Dataset Parameter Setting panel.

Remove: Remove the selected dataset(s) from the list

VIEW DATASETS

Plot 2D: open a Graphic Viewer to visualize the dataset.

Options

Run linear inversion after non-linear inversion

if set, both the non-linear inversion and the linear inversion are executed in sequence (cascade) for each of the selected focal planes.

Maximum Levemberg-Marquardt iterations

Maximum number of non-linear inversion restarts; it is a convergence criterion used to terminate the inversion when geodetic data have poor quality and the cost function global minimum cannot be clearly identified (default 20)

Automatic dataset weighting

it automatically determines the weights to assign to each individual InSAR dataset.

General Functions

Find a focal mechanism

It opens a panel to find the reference focal mechanism to initialize the procedure. After identifying the focal mechanism, the user must specify the focal plane for which the inversion will be performed.

Automatic inversion folder

A folder is created where the automatic inversion is executed. Inside this folder, a sub-folder named FP1 and/or FP2 is created, depending on the choice of which focal plane of the mechanism to consider for the inversion.

Start

Start of the processing.

Cancel

The window will be closed.

Help

Specific help document section.

References

Atzori, S., Monterroso, F., Antonioli, A., De Luca, C., Svigkas, N., Casu, F., Manunta, M., Quintiliani, M. and R. Lanari, Automatic seismic source modeling of InSAR displacements, International Journal of Applied Earth Observation and Geoinformation, Volume 123, 2023, 103445, https://doi.org/10.1016/j.jag.2023.103445.

Interferometry - Displacement Modeling - Automatic Inversion single source - Automatic Inversion

Interferometry - Displacement Modeling - Automatic Inversion single source - Automatic Inversion

Purpose