Isostatic Residual

The Isostatic Residual extension uses a modified version of the USGS algorithm to calculate the Airy isostatic regional and residual gravity from a topographic grid.

The extension calculates a depth to the Moho (the "root") using the topographic grid, terrain density, Moho density contrast and depth of sea level compensation. It then calculates the 3-D gravity response of that root, at sea level, out to 166.7 km. The output must be combined with a solution beyond 166.7 km to make a complete Airy regional.

Working in Oasis montaj requires a Project (*.gpf) . A project encompasses every item in your workspace, from the data files in your project (e.g., databases, grids, maps, voxels, geosurfaces, 3D views, etc.) to the tools used (histograms, scatter plots, etc.) and the project setup including the menus you have displayed.

To start working with the Isostatic Residual extension, we recommend that you open a new project and then load the Isostatic Residual related menus.

Open a new project:

  1. On the Project menu select New. The New Project dialog opens.

    You can also select the Create new project option on the startup dialog, which is displayed when you launch Oasis montaj.

  2. In the New Project dialog, specify the name and location of your new project file (*.gpf) and click the Save button.

  3. The new project is opened, which enables the main menus, the icons on the main toolbars, and the Project Explorer. These visual clues indicate that you are ready to start working with the system.

Load the menu(s):

  1. On the Project menu select Manage Menus, or click the Manage Menus icon on the Project Explorer toolbar. The Manage Menus dialog appears.

  2. Expand the Extensions node, select the Isostatic Residual entry and click OK. The Isostatic Residual related menus will appear on the main menu bar.
    The menu system has been structured to enable you to quickly access a variety of tools and to provide an easy-to-use workflow to lead you through the main processing and filtering functions you can perform with the extension.

Once you have loaded the menu(s), you will have access to the Isostatic Residual Help by clicking on the Help button on any of the dialogs:

    • The reference Help topic for the dialog of interest will appear.

    • You can navigate to another topic of interest from the Help Topics tab.

    • You can search for a specific topic by typing in keywords in the Search tab.