Initial Conditions

Initial conditions from file

Switch on with enable_read_initial_field=.true.

This option requires an input file specified by IniCondPath, init_filename with initial elevation [meters] at each grid node, one value per line.

Idealised source

Switch on with enable_idealised.

An idealised bell is computed, centered at the epicenter given with ideal_epi_lon, ideal_epi_lat and scaled arccording to the magnitude ideal_mw and the rigidity ideal_rigidity as specified in tsunami.namelist, &model_init_idealised. The sea surface and the bathymetry, topography is elevated by this bell.

Currently, only a cosine bell ideal_shape='cosine' scaled according to Strasser 2010 ideal_scaling=``strasser is implemented.

Handle this option with care! This simple assumption allows to place tsunami sources w/o any regard to the geophysical situation.

Okada parameters

Switch on with enable_okada_scenario.

Okada parameters require two input files. The first file’s name is set by okada_parameter_file and contains a list of subfaults, one per row. Each subfault is specified by

  • Longitude and Latitude [°E], [°N] of the southwest corner of the subfault
  • Slip [m]
  • Length [m]
  • Width [m]
  • Strike [°]
  • Dip angle [°]
  • Depth of top [m]
  • Rake angle [°]
  • Longitude and Latitude [° E], [° N] of the southwest corner of the domain in which the bottom displacement due to this subfault shall be calculated.

The vertical bottom displacement due to this subfault is then calulated in a domain of 16°40’ \times 16°40’ originating in the second Logitude, Latitude given.

E.g., for the 2004 tsunami, the subfaults as proposed by Tanioka et al. (2006), Model B, would require an okada_parameter_file like

95.55  2.37 26.10 100000. 100000. 340.00 10.00 10000. 90.00 88.00 0.00
95.20  3.23  0.00 160000. 100000. 340.00 10.00 10000. 90.00 88.00 0.00
94.20  4.46 29.60 150000.  90000. 340.00 10.00 10000. 90.00 88.00 0.00
93.68  5.75  7.30 150000. 100000. 340.00 10.00 10000. 90.00 88.00 0.00
94.33  5.51 10.90 150000. 100000. 340.00 10.00 27000. 90.00 88.00 0.00
92.87  6.79  7.80 150000. 100000. 340.00 10.00  5000. 90.00 88.00 0.00
93.70  7.02  0.00 150000. 100000. 340.00 10.00 22000. 90.00 88.00 0.00
92.40  8.14 12.10 150000. 100000. 340.00 10.00  5000. 90.00 88.00 0.00
93.24  8.38 16.50 150000. 100000. 340.00 10.00 22000. 90.00 88.00 0.00
92.34  9.63 16.60 100000. 110000. 340.00 10.00 10000. 90.00 88.00 0.00
92.04 10.47  7.70 150000. 110000. 340.00  3.00 10000. 90.00 88.00 0.00
92.22 12.11  1.40 100000. 125000.  10.00 17.00  5000. 90.00 88.00 0.00

The second file, okada_fault_list_file, states which subfault ruptures in how many seconds after the initial rupture. It does not have to refer to all subfaults defined in the okada_ parameter_file. For the Tanioka et al. (2006), Model B, example, it reads

10
1    3     4     5     6     8     9    10    11    12
0.0 60.0 180.0 180.0 300.0 420.0 420.0 480.0 600.0 720.0

The first figure gives the total number of rupturing subfaults. The second row defines the subfaults that are to be considered. And the third row gives the time in seconds after the initial rupture at which each subfault is taken into account.

QuakeML

Experimental. So far, only Earthquake epicenter and magnitude are used to set up an idealised source (cosine bell).

In contrast to the other options to initialise TsunAWI, which are usually specified in the namelist, the QuakeML is passed via the command line.

It requires TsunAWI to be compiled with FoXy (Fortran XML parser for poor people, https://github.com/Fortran-FOSS-Programmers/FoXy) to parse XML input.

The approach is quite simple and needs further discussions with seimologists. We assume that the first of multiple entries is the most important/probable one. The quakeml input file is thus parsed as follows:

  1. Find the first block <q:quakeml>
  2. In this block, find the first entry <eventParameters>
  3. Step further down to the first <event>
  4. From the first <origin>, extract the first
    • <longitude>, <value>
    • <latitude>, <value>
  5. From the first <magnitude>, extract the <value>

If a scenario ID is not given on the command line (-id), the name of the QuakeML is taken. However, as they are usually just called quakeml.ml or similar, this is not an optimal choice.

We plan to add the momentum tensor, which can be specified in QuakeML format, as an initial condition to TsunAWI.

However, to get more out of a typical QuakeML file, e.g. to start multiple tsunami simulations for multiple entries or for earthquake parameters specified with confidence intervalls, consider to parse the QuakeML input in a preprocessing step. Furthermore, Fortran is really not the best tool to read XML format…

RuptGen scenarios

Switch on with enable_ruptgen_scenario=.true..

A RuptGen scenario is a special case of a simulation with initial conditions read from a file. If enable_read_initial_field=.false., the input file name is set automatically in TsunAWI as ssh0_mwM.M_XXX_YY.out with M.M, XXX, YY being string representation of mw, Epi_i, Epi_j.

The netcdf output file is named SZ_mwM.M_XXX_YY.nc.

These initial conditions at the nodes of the computational grid have to be calculated in advance with RuptGen (A. Babeyko, GFZ). The meta data in the netcdf file and the netcdf filename itself are then set according to the GITEWS conventions.