[CIG-SEISMO] Problem with external velocity model

[Dimitri Komatitsch]

Hi Moritz,

Are you using the internal mesher, or an external model and external mesh?

Thanks,
Dimitri.

On 10/10/2018 07:27 AM, Fehr, Moritz wrote:
> Hi,
> 
> I have some issues using an external velocity model with ”low“ 
> velocities. The model size is 3 x 3 x 2.52 km and the mesh size is 40 m 
> in all directions. The velocity model is discretized with 40m as well.
> 
> If  I  use my initial velocity model with minimum velocities Vp = 2263 
> m/s and Vs = 1307 m/s the simulation works fine. In the next step I 
> wanted to implement a low velocity patch within the initial velocity 
> model (see: v_model_patch.png) to investigate the influence of the low 
> velocity body. The minimum velocities are Vp = 955 m/s and Vs = 555 m/s 
> (blue). The problem is that SPECFEM do not detect these low velocities 
> (see output_solver.txt) and the simulation provides the same results as 
> the initial simulation. I also tried different mesh sizes and velocity 
> model spacing but the problem still remains. Do anybody have an idea 
> about the origin of that issue?
> 
> Thanks
> 
> Moritz
> 
> PS: I am using SPECFEM3D Cartesian (Version 3.0) with two GPUs (Tesla 
> K40m) and 28 CPUs.
> 
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-- 
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr