# Seeking TauP tvel and model building advice

**URL:** <https://discourse.obspy.org/t/seeking-taup-tvel-and-model-building-advice/2118>\
**Category:** Usage Questions\
**Created:** [December 12, 2024, 11:39pm UTC](https://discourse.obspy.org/t/seeking-taup-tvel-and-model-building-advice/2118 "2024-12-12T23:39:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![SquirrelKnight](https://discourse.obspy.org/user_avatar/discourse.obspy.org/squirrelknight/32/460_2.png) [@SquirrelKnight](https://discourse.obspy.org/u/SquirrelKnight)\
**Post date:** [December 12, 2024, 11:39pm UTC](https://discourse.obspy.org/t/seeking-taup-tvel-and-model-building-advice/2118/1 "2024-12-12T23:39:35Z")

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I am working on a 1D locator that simply uses TauP and Scipy’s minimization function. Currently, I am using the ‘ak135’ model, but it is not entirely suitable for my study region, which is located offshore near a spreading centre. I do have a velocity model which I attempted to prepend to the ak135 model, however I am unable to calculate raypaths for S phases within the upper 8 - 10 km.

Below, I have copied velocity structure that I am using for region, with a depth of 0 being the seafloor. I feel like I am missing out on something important here, but am unsure of how to properly build the tvel file to work. Advice is greatly appreciated!

```python
   0.00 2.61 0.87 1.6052
   0.20 2.71 0.90 1.6372
   0.40 4.79 2.78 2.3028
   0.60 5.06 2.94 2.3892
   0.80 5.23 3.04 2.4436
   1.00 5.66 3.29 2.5812
   1.20 5.94 3.45 2.6708
   1.40 6.05 3.52 2.706
   1.60 6.17 3.58 2.7444
   1.80 6.28 3.65 2.7796
   2.00 6.50 3.78 2.85
   2.20 6.55 3.81 2.866
   2.40 6.59 3.83 2.8788
   2.60 6.62 3.85 2.8884
   2.80 6.66 3.87 2.9012
   3.00 6.69 3.89 2.9108
   3.20 6.72 3.91 2.9204
   3.40 6.76 3.93 2.9332
   3.60 6.79 3.95 2.9428
   3.80 6.83 3.97 2.9556
   4.00 6.86 3.99 2.9652
   4.20 6.90 4.01 2.978
   4.40 6.93 4.03 2.9876
   4.60 6.97 4.05 3.0004
   4.80 7.00 4.07 3.01
   5.00 7.04 4.09 3.0228
   5.20 7.07 4.11 3.0324
   5.40 7.11 4.13 3.0452
   5.60 7.14 4.15 3.0548
   5.80 7.18 4.17 3.0676
   6.00 7.21 4.19 3.0772
   6.20 7.25 4.21 3.09
   6.40 7.28 4.23 3.0996
   6.60 8.20 4.77 3.394

```

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**Author:** ![droessler](https://discourse.obspy.org/user_avatar/discourse.obspy.org/droessler/32/545_2.png) [@droessler](https://discourse.obspy.org/u/droessler)\
**Post date:** [January 7, 2025, 8:07am UTC](https://discourse.obspy.org/t/seeking-taup-tvel-and-model-building-advice/2118/2 "2025-01-07T08:07:48Z")

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Hi @SquirrelKnight,

whether or not the travel-times can be computed may depend on the solver of the software you are using.

I therefore recommend you first demonstrate how you try to compute the travel-time tables and what errors occur. There are very many open-source and closed-source options/software to compute travel-time-tables.

One option is to use the OpenSoure taup package [1] itself by running:

```python
taup_create [options]
taup_table [options]

```

In this approach the model may need to be extended down to the Earth core which can be achieved by padding ak135 for the remaining depths.

Regards,  
Dirk ([gempa GmbH / SeisComP](https://www.gempa.de/))

[1] [USC Seismology - TauP](https://www.seis.sc.edu/taup/index.html)