Input of VOLNA (version 3 from December, 2014)

Summer Zheng

Report up to 17/07/2015

In this report, I will explain the format, the size, and the structures of input files for VOLNA.

1 Input of VOLNA: mesh and bathymetry files

To propagate the tsunami wave from earthquake, we need mainly two things: the ”mesh” (as the com-putational domain of Cascadia, triangular mesh for finite element approach) and the ”bathymetry”(as the shape of seabed and shore underneath the water). Please see Figure 1 as a simple non-specialists’ overview of input files of VOLNA. As a specialist, a more detailed plot is given in Figure2.

Figure 1: Input of VOLNA: mesh files and bathymetry files. They will be explained in the followingsections. (For nonspecialists)

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Figure 2: Input of VOLNA: mesh files and bathymetry files. They will be explained in the followingsections. (For specialists)

2 Big refined triangular mesh file in Cascadia

”.msh” fileSize: about 150 MB2392352 triangles, 1197384 nodesx ∈ [−570000, 370000], y ∈ [−1000000, 850000]two formats: 1) ASCII format (you will be able to open as a .txt file to see the numbers); 2) binaryformat (it is recognized by VOLNA, thus being the input)You may visualize the big mesh with 2392352 triangles in the software ”gmsh” as in Figure 3.

3 Smaller coarse mesh specifying the uplift in Cascadia

”.txt” fileSize: about 25KB.The range of x,y can be anything within the range of the big refined triangular mesh.It saves the storage space such that we do not need to save a 200MB file.When you open this .txt file, the meaning of the list of numbers is explained in Figure 4. Also, anexample with 702 triangles is given.

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Figure 3: Visualizing the big mesh file in Cascadia by the software ”gmsh”. (2392352 triangles)

4 Bathymetry on the big refined mesh

”.txt” fileSize: about 25MB.Content: it is a column of numbers, indicating the initial value of bathymetry on the barycenters ofeach triangle in the big refined triangular mesh in Cascadia. The order of the bathymetry values arein the same order as the list of triangles indicated in the big bathymetry file (the .msh file).In Figure 5, you may visualize the initial bathymetry data in Cascadia on the big refined mesh (asgiven in Figure 3).

5 Uplift on the smaller coarse meshes

”.txt” fileSize: about 4KB each.Update this file for ever 10 time steps.Content: it is a column of numbers, as the uplift on the nodes of the coarse mesh (not barycenters).In Figure 6, you may visualize an example of uplift specified on the coarse mesh (as given in Figure4) at the 50th and the 2000th time steps.

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Figure 4: Visualizing an example of a small coarse mesh file for the uplift in Cascadia by the software”gmsh”. (2392352 triangles)

Figure 5: Visualize the initial bathymetry data in Cascadia on the big refined mesh (as given inFigure 3)

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Figure 6: Visualize an example of uplift specified on the coarse mesh (as given in Figure 4) at the50th and the 2000th time steps.

6 A note to myself:

The bathymetry on the big refined mesh is given on the barycenters of triangles. The uplift on topof this bathymetry on the smaller coarse meshes is given on the nodes of triangles.

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