File Formats for source models

For each source model in this database, three different data files are provided

• evTAG.slp (ascii-file with basic header information and simple, single-rupture-plane source-model representation)
• evTAG.fsp (ascii-file with comprehensive list of modeling/inversion parameters, source geometry, and space-time-dependent rupture model)
• evTAG.mat (binary MATLAB file containing the rupture model as MATLAB structure)

evTAG is a 15-character-string composed of the year of the earthquake, an abbreviation for the event location and an abbreviation for the author(s) of the source model.

---

Source-model geometry

• The geometry of the source representation follows the Aki & Richards (1980, 2002) convention. The strike of the fault plane (or any segment of it), representing the azimuth of the fault's projection onto the surface, is measured from North (positive in clock-wise direction), the dip of the fault (or individual fault segments) is measured downward from the surface to the fault in the vertical plane perpendicular to the strike. The strike direction is defined such that the dip-angle is smaller than 90 deg (i.e. using the right-hand rule with the thumb oriented in postive strike direction, your hand rotates downward from the horizontal into the fault plane by an angle less than 90 deg).
• We adopt a default viewing angle of (strike + 105 deg) to display the 3D-geometry of the source model, although we make exceptions for a number of events to either optimize the image or to honor "standard" viewing angles that have been used repeatedly in the past for specific cases (e.g. the 1992 Landers earthquake).
• The geometrical representation uses the top-center of each fault segment and each subfault as reference; latitude, longitude and depth for each segment/subfault are provided as well as X (EW, positive toward E) and Y (NS, positive toward N) coordinates with origin at the epicenter, computed using UTM-coordinates based on the UTM-zone of the epicenter. Hence, geometrical biases or small deviations from other sources or published images may occur if the epicenter is located close to a border of an UTM zone.
• Note: For most multi-segment events in the database, latitude/longitude information for the individual segments had to be extracted from published images or was estimated from incomplete data. The 3D-representation of these rupture models is hence only approximate and should be carefully checked for subsequent studies in which geometrical accuracy at a 10-meter-scale (or smaller) is needed.
• The figure below summarizes the geometrical source representation:

---

File Format evTAG.slp

• Slip values (potentially also rake, rise time, or rupture onset time) are arranged into a 2D array with the along-strike direction printed in rows, the down-dip direction printed in columns, starting at the top-left corner of the rupture plane when viewed at an angle of 90 deg from strike.
• Multi-segment ruptures are projected onto a single rupture plane using an average strike of all (or the most prominent) segments.
• The header provides the most important source and modeling parameters:

• Event name, Event date, Reference
• Eventtag
• LATitude, LONgitude and DEPth of the of the hypcenter
• LENgth of and WIDth of the rupture plane, moment magnitude Mw and seismic moment Mo
• Average STRiKe and DIP of fault plane, average RAKE of slip vector, vertical depth to top of rupture plane (HTOP)
• HypX, HypZ: rupture nucleation point in fault-plane coordinates (starting at top-left corner)
• avTr, avVr: average rise time and rupture velocity
• inDx, inDz: subfault size in along-strike and down-dip direction, respectively,
• Fmin, Fmax: minimum and maximum frequency of bandpass filtered seismic data (Fmin = Fmax = 0 for purely geodetic models)
• Nx, Nz: number of subfaults in each direction (x: along-strike, z: down-dip)
• Note: zero entries indicate that the parameter doesn't apply to this source model; the value = -99 means this parameter is spatially variable over the fault plane; the value = 999 indicates that the value is currently not known, but should be present.

% ------------------------- FINITE-SOURCE SLIP MODEL ---------------------------
%
% Evnt : Imperial Valley (Calif.) 10/15/1979 [Archuleta(1984)]
% EventTAG: s1979IMPERIarch
%
% Loc : LAT = 32.644 LON = -115.309 DEP = 8.00
% Size : LEN = 35.00 km WID = 13.00 km Mw = 6.53 Mo = 6.99e+018 Nm
% Mech : STRK = 323 DIP = 80 RAKE = 180 Htop = 0.01 km
% Rupt : HypX = 0.00 km HypZ = 8.00 km avTr = 0.9 s avVr = -99.0 km/s
% Invs : inDx = 2.50 km inDz = 1.00 km Fmin = 0.00 Hz Fmax = 1.0 Hz
% Invs : Nx = 14 Nz = 15
%
% Check corresponding file -- s1979IMPERIarch.fsp -- for details & exact geometry
%
% rows : source-parameter values in along-strike direction (row 1 == top)
% cols : source-parameter values in down-dip direction
%
% 22-Jul-2007, collected by P.Martin Mai (mai@sed.ethz.ch)
% --------------------------------------------------------------------------------
% ----------------------------- TOTAL SLIP [m] -------------------------------
0.00 0.00 0.00 0.26 0.26 0.23 0.18 0.17 0.11 0.12 0.14 0.18 0.22 0.11 0.03
0.00 0.00 0.00 0.20 0.20 0.13 0.15 0.14 0.10 0.11 0.13 0.15 0.20 0.09 0.03
0.00 0.00 0.00 0.11 0.11 0.11 0.12 0.11 0.12 0.12 0.13 0.15 0.20 0.10 0.02
........ many rows omitted here ....

% ------------------------ RUPTURE ONSET TIMES [sec] -------------------------
5.47 6.32 6.64 7.21 7.78 8.36 8.95 9.77 10.59 11.31 12.03 12.33 12.62 13.28 13.92
4.47 5.15 5.16 5.70 6.49 7.03 7.57 8.01 8.46 9.06 9.81 10.47 11.14 11.68 12.33
4.26 4.94 4.82 5.03 5.62 6.22 6.81 7.42 7.84 8.33 9.27 9.97 10.67 11.57 12.33
........ many rows omitted here ....

File Format evTAG.fsp

• The *fsp (finite-source parameter) provides a comprehensive description of modeling/inversion parameters and the finite-source rupture parameters, starting with a header block, then listing source parameters on the fault plane, potentially segment by segment (in case of multi-segment events).
• The length of the header block is variable, depending on the velocity-density structure, but can be inferred from the information given in the header.
• The rupture model is given in a column-format, each column presenting a different quantity; each row represents one point (subfault) on the rupture plane, arranged starting from the top left corner of the fault plane, and progressing first along-strike, then down-dip, to the bottom-right of the faults.
• The number of columns (source parameters) may be variable for different rupture models, depending on what source parameters are available. The minimum number of columns is SIX (Lat, Lon, X, Y, Z, SLIP), while the maximum number is unlimited. Additional columns may comprise RAKE, RISE time, TRUP (rupture onset time), or slip (and perhaps rake) in subsequent time windows (indicated as TW1 and rkTW1, TW2 rkTW2, etc ....
• If the source model has been obtained using various fault segments, the data are given segment-by-segment in the same manner as just described, where each segment is preceeded by a 9-line header block with segment specific meta-data.
• The header comprises basic earthquake source parameters and meta-data on he modeling /inversion approach; besides the parameters described above for the evTAG.slp format, some additional entries are given:

• Ntw, Nsg: number of time-windows, and number of fault segments, respectively
• LEN, SHF: length (in sec) of slip-function, and the overlap (in sec) of successive time-windows
• SVF: type of slip-velocity function used in the inversion
• In the Data-section, the number of stations are listed for the different types of data used in the inversion; PHmx is a rough estimate of the maximum angle between any two neighboring stations (ie. PHmx > 180 deg means the event was outside the observational array). Rmin estimates the distance of the closest station to the nearest point on the fault.
• Data on the velocity-density structure at the source is preceeded by the corresponding number of layers.
• Nsbfs: number of sub-faults, either for the single-plane rupture or given for each segment separately.

% ---------------------------- FINITE-SOURCE RUPTURE MODEL --------------------------------
%
% Event : Kobe (Japan) 01/17/1995 [Sekiguchi etal (2000)]
% EventTAG: s1995KOBEJ1seki
%
% Loc : LAT = 34.598 LON = 135.044 DEP = 16.37
% Size : LEN = 63.55 km WID = 20.50 km Mw = 6.99 Mo = 3.44e+019 Nm
% Mech : STRK = 45 DIP = 85 RAKE = 180 Htop = 1.00 km
% Rupt : avTr = 3.3 s avVr = 3.1 km/s
%
% ---------------------------- inversion-related parameters --------------------------------
%
% Invs : Nx = 31 Nz = 10 Fmin = 0.10 Hz Fmax = 1.0 Hz
% Invs : Dx = 2.05 km Dz = 2.05 km
% Invs : Ntw = 6 Nsg = 5 (# of time-windows,# of fault segments)
% Invs : LEN = 0.80 s SHF = 0.30 s (time-window length and time-shift)
% SVF : tanhyp (type of slip-velocity function used)
%
% Data : SGM TELE GPS tril level
% Data : 25 0 0 0 0
% PHImx: 110 0 0 0 0
% Rmin : 0.2 0.0 0.0 0.0 0.0
%
% -----------------------------------------------------------------------------------------
%
% VELOCITY-DENSITY STRUCTURE
% No. of layers = 4
%
% DEPTH P-VEL S-VEL DENS QP QS
% [km] [km/s] [km/s] [g/cm^3]
% 0.00 5.50 3.20 2.60 9999 9999
% 5.10 6.00 3.46 2.70 9999 9999
% 18.00 6.70 3.87 2.80 9999 9999
% 34.50 7.50 4.33 3.00 9999 9999
%
% -----------------------------------------------------------------------------------------
% 18-Jul-2007, created by P.Martin Mai (mai@sed.ethz.ch)
% -----------------------------------------------------------------------------------------
%
% SOURCE MODEL PARAMETERS
% X,Y,Z coordinates in km; SLIP in m
% if applicable: RAKE in deg, RISE in s, TRUP in s, slip in each TW in m
%
% Coordinates are given for top-center of each subfault or segment: |'|
% Origin of local coordinate system at epicenter: X (NS) = 0, Y (EW) = 0
% ------------------------------------------------------------------------------------------
% --------------------------- MULTISEGMENT MODEL -------------------------------------------
% ------------------------------------------------------------------------------------------
% SEGMENT # 1: STRIKE = 45 deg DIP = 78.0 deg
% LEN = 20.50 km WID = 20.50 km
% depth to top: Z2top = 1.00 km
% coordinates of top-center:
% LAT = 34.5530, LON = 134.9402
% hypocenter on SEG # 1 : along-strike (X) = 20.50, down-dip (Z) = 15.37
% Nsbfs = 100 subfaults
% -------------------------------------------------------------------------------------------
% LAT LON X==NS Y==EW Z SLIP RAKE TW1 rkTW1 TW2 rkTW2 ...
% -------------------------------------------------------------------------------------------
34.4943 134.8689 -11.5234 -16.0192 1.0000 0.224 166.504 0.057 108.435 0.000 90.000 ...
34.5073 134.8847 -10.0738 -14.5696 1.0000 0.876 221.820 0.205 222.797 0.148 250.201 ...
34.5204 134.9006 -8.6242 -13.1200 1.0000 0.647 241.314 0.005 90.000 0.128 220.101 ...

........ many rows omitted here ....

File Format evTAG.mat

• The *mat-file provides essentially the same information as the *fsp ascii-file, saved in a convenient and user-friendly MATLAB-structure. Type 'load evTAG.mat' at the MATLAB-prompt (replace evTAG with the model name), and you will get a structural array of the corresponding model. The various structural fields are labeled in a self-explanatory manner (at least I hope so); field-names in these structures are often similar to the parameters described for the *fsp-file format.
• An example for the 1992 Landers earthquake (model by Wald et al, 1993) is given below; for other events or rupture models, the details of the MATLAB-structure may vary, while only the initial parts are unchanged:

s1992LANDERwald =

a1: '================='
a2: 'EVENT PARAMETERS'
a3: '================='
event: 'Landers (Calif.)'
evDAT: '06/28/1992'
evTAG: 's1992LANDERwald'
evLON: -116.4300
evLAT: 34.2000
evDPT: 7
a4: '==========================='
a5: 'GENERAL SOURCE PARAMETERS'
a6: '==========================='
srcDimWL: [15 78]
srcMwMoS: [7.2778 9.2629e+019]
srcHypXZ: [11 7]
srcARake: 180
srcAStke: 330
srcDipAn: 89
srcZ2top: 0
srcAveVr: 2.7000
srcAveTr: 6
b1: '=========================='
b2: 'Single-plane SOURCE MODEL'
b3: '=========================='
slipSPL: [6x26 double]
i0: '====================='
i1: 'INVERSION PARAMETERS'
i2: '====================='
invSEGM: 3
invNoTW: 6
invNzNx: [6 26]
invDzDx: [2.5000 3]
invFreq: [0 0.5000]
invDtyp: {'SGM' 'TELE' 'TRIL' 'LEVEL' 'GPS' 'INSAR' 'SURF' 'OTHER'}
invNsta: [16 11 0 0 42 0 0 0]
invPmax: [63 73 999]
invRmin: [11.3000 35.7000 999]
invSVFc: 'triang'
invTwin: [6 1 0]
invVstr: [5x6 double]
invAUTH: 'Wald and Heaton(1994)'
s0: '=========================='
s1: 'FAULT SEGMENT INFORMATION'
s2: '=============================='
s3: 'Fault Segment # 1'
seg1SLIP: [6x10 double]
seg1AStke: 355
seg1DipAn: 90
seg1Z2top: 0
seg1DimWL: [15 30]
seg1cen: [34.2280 -116.4350]
seg1hypXZ: [11 7]
s4: '=============================='
s5: 'Fault Segment # 2'
seg2SLIP: [6x9 double]
seg2AStke: 334
seg2DipAn: 90
seg2Z2top: 0
seg2DimWL: [15 27]
seg2cen: [34.4150 -116.4800]
s6: '=============================='
s7: 'Fault Segment # 3'
seg3SLIP: [6x12 double]
seg3AStke: 320
seg3DipAn: 90
seg3Z2top: 0
seg3DimWL: [15 36]
seg3cen: [34.5720 -116.5900]
seghypo: 1
segcoord: 'latlon'
seg3slipTW1: [6x12 double]
seg3slipTW2: [6x12 double]
seg3slipTW3: [6x12 double]
seg3slipTW4: [6x12 double]
seg3slipTW5: [6x12 double]
seg3slipTW6: [6x12 double]
seg2slipTW1: [6x9 double]
seg2slipTW2: [6x9 double]
seg2slipTW3: [6x9 double]
seg2slipTW4: [6x9 double]
seg2slipTW5: [6x9 double]
seg2slipTW6: [6x9 double]
seg1slipTW1: [6x10 double]
seg1slipTW2: [6x10 double]
seg1slipTW3: [6x10 double]
seg1slipTW4: [6x10 double]
seg1slipTW5: [6x10 double]
seg1slipTW6: [6x10 double]
zz1: '======================='
zz2: 'ADDITIONAL INFORMATION'
zz3: '======================='
gg0: '========================='
gg1: ' Geometry Information '
gg2: 'X==EW Y==NS Z==pos-down'
gg3: '========================='
FEregion: 'Southern California, United States'
FEregionNo: '043'
seg1geoX: [6x10 double]
seg1geoY: [6x10 double]
seg1geoZ: [6x10 double]
seg1geoLAT: [6x10 double]
seg1geoLON: [6x10 double]
seg2geoX: [6x9 double]
seg2geoY: [6x9 double]
seg2geoZ: [6x9 double]
seg2geoLAT: [6x9 double]
seg2geoLON: [6x9 double]
seg3geoX: [6x12 double]
seg3geoY: [6x12 double]
seg3geoZ: [6x12 double]
seg3geoLAT: [6x12 double]
seg3geoLON: [6x12 double]
geoViewAng: 225
zz7: '================================='
zz8: '18-Jul-2007 PMM (mai@sed.ethz.ch)'
zz9: '================================='

SRCMOD File Formats