Specfem3D_globe for PKIKP phase

Hi there,

We plan to use Specfem3D_globe to study CMB with velocity tomography models. We already installed the package, and succeeded to get synthetic waveforms with setting NPROC_XI(ETA)=8, and NEX_XI(ETA)=512 due to limit of computational power. However for PKIKP, we prefer to get precision as ~2Hz, therefore we need bigger number for NEX_XI(ETA). What else parameters should I change to make it work with limit of computational power?
Your suggestion will be appreciated in advance.

Jiaming

Jiaming,

you are looking for a 2 Hz global simulation with 3D earth models using a spectral-element code? then you are probably out of luck with the SPECFEM3D_GLOBE code as there is currently no supercomputer big enough to achieve that. however, CIG also hosts the AxiSem code that might help you out with this.

-daniel

Daniel,

Well, maybe not that big. :slight_smile:
Actually we only need 3D velocity model in small region around inner/outer core boundary, the rest is 1D earth model for PKIKP phase.
This should work, right?

Jiaming

the runtime of a SPECFEM3D_GLOBE simulation is independent of having a 1D or 3D model. that is, running a simulation for a 1D model is as expensive as running it for a 3D model. so it doesn’t matter if you only want a portion of the Earth to be 3D.

you could only save time by turning off some of the physics (attenuation, ocean, gravity, rotation) or by limiting the simulation to a 1-chunk, regional simulation.

concerning the maximum frequency range for global simulations, Laura went down to 2s in 2008 on Ranger (High-frequency simulations of global seismic wave propagation using SPECFEM3D_GLOBE on 62K processors - IEEE Conference Publication), Seiji went down to 1.2s in 2016 on the K computer (https://journals.sagepub.com/doi/full/10.1177/1094342016632596). having a global 2Hz simulation is not achievable yet with current HPC systems, mostly due to memory limitations.

try looking into AxiSem and AxiSEM3D (GitHub - kuangdai/AxiSEM3D) which might help you with your 2Hz setup (https://academic.oup.com/gji/article/217/3/2125/5333339).