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This page has descriptions of the file formats that we use in various places.

SRF Format

• https://strike.scec.org/scecpedia/Standard_Rupture_Format
• SRF-Description-Graves_2.0.pdf
• SRF File Format Version 1 (output of genslip): srf_description_version_1.pdf
• Details on Source Modelling : Source Modelling for GMSim

SRF info format

The .info files that accompany .srf files are in HDF5 format

Example (CBalleny.info)

Stoch format

LF/HF/BB binary format

These files store timeseries data. All formats follow a style derived from the LF seis format produced by EMOD3D:

...

XYTS.e3d binary format

This file is produced by EMOD3D and contains a timeseries of ground motions on the XY plane. Unlike the LF seis files, this contains data at all grid points and may have a decimated resolution specified when running EMOD3D through the e3d.par file with the parameters dxts and dyts.

Numbers are 4 bytes in length and may be little or big endian. You can see or use the existing interfaces that also take care of endianness at github:ucgmsim/qcore/qcore/xyts.py::XYTSFile.

File size can be derived knowing the format and the shape of time-series (all necessary values are at the beginning of the file).

...

1. simulation metadata
   1. INTEGERS
      1. number of first x gridpoint
      2. number of first y gridpoint
      3. number of first z gridpoint
      4. number of first timestep
      5. number of x gridpoints
      6. number of y gridpoints
      7. number of z gridpoins (always 1 by definition of X-Y file)
      8. number of timesteps
   2. FLOATS
      1. x spacing between given gridpoints (km)
         
      2. y spacing between given gridpoints (km)
      3. original (pre-decimated) grid spacing between gridpoints used in simulation (km)
      4. timestep in timeseries (s)
      5. model rotation of gridpoints (degrees)
      6. model centre latitude (degrees)
      7. model centre longitude (degrees)
2. timeseries
   • float array of velocities in the dimentions of timesteps, components (x, y, z), y grid positions, x grid positions.

Intensity Measure calculation

The IM calculation code will produce a number of text files (decided as of 25/05/2018). We will summarize them in the following.

Intensity measure files

There are two types of IM files: per station and aggregate. The per station one has the following format:

...

station, component, IM_1, IM_2, ...., IM_N

Empirical IMs

As above the empirical intensity measures have a similar format:

...

Notes: 1) the component for empirical IMs is always 'geom' 2) only total sigma is saved to the csv file

Rrup file

The file format for this is:

...

Note: we don't have rx calculations yet, so we may dump an invalid value just to conform with the format.

Metadata file

So far the requirements indicate that we need:

identifier, rupture, type, date, version

GSF File

The GSF file is used to define the geometry of a source in a source modelling problem. It is the first step in the SRF generation process after a realisation is read.

A GSF file contains three sections in order:

1. Errata/Header section,
2. Declaration of the number of points (N),
3. The geometry description: N lines representing each point in the geometry.

There are utilities to read GSF files in the gsf  module within qcore.

Example File

Below is a discretisation of the Acton fault. You can visualise this gsf file use the gsf_plot script in the visualisation repo under the sources folder.

Errata/Header

The header consists of a number of commented lines, each beginning with # . Here is an example:

# nstk= 179 ndip= 215
# flen=    17.0720 fwid=   21.2853
# LON  LAT  DEP(km)  SUB_DX  SUB_DY  LOC_STK  LOC_DIP  LOC_RAKE  SLIP(cm)  INIT_TIME  SEG_NO

This is the typical output of fault_seg2gsf . The first line has the number of points in the strike and dip directions, respectively. Then the length and width of the fault, and the last line is a description of each column in the points section.

The header is skipped by programs parsing GSF files and may contain any number of lines. The Python GSF generator, for example, only prints out the column description.

# LON  LAT  DEP(km)  SUB_DX  SUB_DY  LOC_STK  LOC_DIP  LOC_RAKE  SLIP(cm)  INIT_TIME  SEG_NO

Declaration of the Number of Points

Immediately following the header, there is one line containing the number of points in the GSF geometry definition.

Geometry Description

The geometry description has N lines, where N is the number of points declared in the previous section. Each line has 11 space separated values representing one point in the geometry.

Here an example of a line from the Acton fault GSF file.

  168.36970   -45.45649 6.04586e-01 9.58498e-02 9.94142e-02  196.0   60.0  110.0    -1.00    -1.00   0

Point Order

The order of the points is important! The points must be in order of first strike and then dip. That is to say, first every point on all planes at depth = 0 should be written, then depth = 1, depth = 2, and so on and the order of the points at a fixed depth = i is in order of strike. Refer to the diagram below.

Image Added