Elastic deformation

Here you can either import a line (or polyline) or draw it over your image grid. That line is than interpreted as a surface trace of a fault. Right clicking on the line will show (among others) two options to call new windows where you will specify the fault parameters (width, depth, dip) as well as the movement you will simulate. The two available options are called Okada and Mansinha. The Okada window is more general and oddly nearly twice fast and here you can: model co-seismic displacement - that can be compared with GPS measuring - for an initial condition of the far field tsunami modeling (see below) or to compute synthetic interferograms. The Okada window provides short help in the form of tooltips when the mouse rests a bit over individual entry boxes. For a complete reference you must read the

RNGCHN paper (Feigl and Dupre 1999; Computers and Geosciences, 25 (6) pp. 695-704). The paper and the source code used to be available on authors ftp site but it seems to have vanished.

The Mansinha option computes only the vertical component of the deformation produced by an earthquake.  The two codes should produce equal results (and they very closely do). On both Okada and Mansinha, a clever guess is made about the type of the grid coordinates. Accepted types are geographical, meters and kilometers. While the guessing works well most of times it may also fail, so please pay attention to the guessed type and corrected if it is not correct. When working with geographical coordinates all distances are computed by previously projecting the geographical coordinates to Transverse Mercator with origin in fault's first point.

The above figure shows an example of Okada use and bellows a figure of the “Mansinha”. Not shown in that figure is the one more of the Mirones fine details. The horizontal projection of the fault(s) plane(s) are displayed on the main window. Also, if you have the Fledermaus viewer installed you can have a 3D visualization of the fault plane. For time being the faults top is placed at “Depth to Top” below the grids minimum and not at the fault lengths average depth + “Depth to Top” as it would be correct.

It is possible to import variable slip models using the SUBFAULT format (well, more like what I could guess that format is since I didnt find any formal format description) or the “Finite-Source Rupture Model Database” SRCMOD (.fsp) format maintained by Martin Mai at www.seismo.ethz.ch/srcmod For that, select “Import Model Slip” and select a file from the window below. As options show, you can compute the cumulated deformation of all individual patches. Off course that it may take some time if you are computing over a large grid.

Copyright © <2010>, <Joaquim Luis>

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