MLOC ttsprd File

~.ttsprd File

A ~.ttsprd file is produced by every run of mloc. It is written by the module mloc_ttsprd.f90. Every phase that is present in the dataset at least twice is processed to obtain the robust estimate of its spread and the baseline offset relative to the theoretical travel-time model. These values can be read into subsequent runs with the command tfil. These values are used in the windowing algorithm (command wind) to provide a procedure for rejecting gross outliers that is more sophisticated than a simple single-limit criterion. That is, the width of the window for each phase is based on the observed spread of arrivals for that phase and the window is offset from the theoretical travel-time model by the observed baseline offset to avoid bias.

The example is the full ~.ttsprd file for a cluster:

P          13088     1.592     2.953
Pn          5423     2.179    -0.591
S            816     4.513     4.471
PcP          173     2.713     2.716
PcS           26     3.016     3.038
PnS           35     2.900    -0.493
SS            88     5.300     2.092
PP           211     3.962     3.770
pP-P          62     1.227     0.246
SKiKP          8     2.677     2.927
SKKSac         9     1.293     0.968
ScS           28     3.592     3.265
SKSac         15     2.789     2.090
PS             7     7.499     5.060
Sn           821     2.637    -1.075
Sg           464     1.355     0.032
Pg          1575     1.346     0.129
Lg           410     3.294     2.857
pP            19     1.298    -1.911
PKiKP        105     1.595     2.329
Pdiff        168     1.062     3.366
PKKPdf        11     3.327     1.861
PKKPbc        19     1.427     3.760
PKPdf         18     1.689     4.479
PKPab          6     1.756    -2.155
sP-P          28     1.220    -0.301
sP            22     1.220    -0.499
ScP           12     2.873     2.034
sS            21     5.003     4.181
P'P'df         8     6.270    -2.066
PKKPab        15     4.855     0.831

The columns are:

  • Phase
  • Number of samples
  • Spread
  • Baseline offset

Notice that the baseline offset of the P phase is significant: almost +3 seconds relative to the ak135 global mode. On the other hand, the phases Pg and Sg have quite small baseline offsets, because the hypocentroid of the cluster has been determined mainly with these phases (direct calibration), using a local velocity model that has been refined to match the observed data. In calibrated relocation analyses it is very common to observe offsets of this magnitude for teleseismic branches.

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