Configuration of the model, data setup and inversion results obtained using LOTOS-07 code are shown in FIGURE 1:
Figure
1. Inversion results using the sources located outside the network.
A and E:
synthetic model
in a horizontal section (
The data for this test can be downloaded using this link: "download inidata.zip" .
The data setup for this test has been produced artificially. The area of the station distribution is roughly isometric and is of ~200 km size. For each of 200 events the number of recorded P picks varies randomly from 25 to 50. For 40%-80% of the recorded P picks we create the S picks. In total, we have produced 12191 pairs of source/receivers corresponding to 7648 P and 4543 S phases. The travel times for this test have been computed using 3D ray tracing (our own version of bending method) through 3D checkerboard model with anomaly of +_ 2%. Then the coordinates and origin times of the sources, as well as "true" 1D model have been "forgotten". Here we present the dataset with approximate locations of sources estimated using an approximate 1D model (the same starting information is used by most of tomographic algorithms). The location of sources and optimization for the 1D model are calculated using the initial steps of LOTOS-07 code.
The "inidata.zip" includes three files:
1. "rays.dat" file which contains travel times and approximate source coordinates located in the 1D reference model "refmod.dat" (also approximate).
First line is a description of an event which includes geographical coordinates: longitude (degree, W-negative), latitude (degrees, S-negative) and depth (km), and number of recorded phases, NPhase.
After the line of source description, NPhase lines follow.
First column is phase indicator (1:P, 2:S), second column is number of
station according to the list in "stat_ft.dat". Third column is travel time, in
second. Below is example for one events from "rays.dat":
-1.317841
0.9982975
31.50000
45
1 15
26.22949
2 15
45.25689
1 34
33.72011
2 34
57.17429
1 8
42.42081
2 8
72.18322
1 11
41.91318
2 11
71.86687
1 5
32.70572
2 5
55.70214
1 7
39.66212
2 7
67.92155
1 43
24.42760
2 43
41.77356
1 13
36.25513
2 13
61.80154
1 26
27.31455
2 26
46.53685
1 2
15.49090
2 2
26.16937
1 40
28.89000
2 40
48.61009
1 14
31.52957
2 14
53.23554
1 27
22.06399
2 27
37.52535
1 1
12.85219
2 1
21.77514
1 4
27.84778
2 4
46.88229
1 41
32.11546
2 41
54.52583
1 18
20.62126
2 18
35.08043
1 29
17.24921
2 29
29.76820
1 38
26.70750
1 20
31.60567
1 10
43.83544
1 30
22.84743
1 47
36.07906
1 37
23.47372
1 35
30.68942
1 23
38.05227
1 16
20.75333
2. "stat_ft.dat" is a file with station
geographical coordinates which includes longitude, latitude and elevation which
is given in km. Positive value means that the station is below sea level. In the
presented synthetic dataset, all the stations are at 1 km depth below sea
level.
-0.7642902
0.6408060 1.000000
-0.5177832
0.8476954 1.000000
-0.1744345
0.9797521 1.000000
0.2701586
0.9577430 1.000000
0.5826951
0.8080777 1.000000
0.8159962
0.5835809 1.000000
0.9656604
0.2930546 1.000000
1.005278 -5.9098393E-02
1.000000
0.8952304
-0.4332605 1.000000
0.6927426
-0.7061793 1.000000
0.3934121
-0.8954611 1.000000