[CIG-SEISMO] help with using the approximate Hessian in SPECFEM3D

[Alan Schiemenz]

Dear SPECFEM3D users,
I am writing to ask about how the "approximate Hessian" feature can be
used for tomographic inversions in SPECFEM3D.  I am hoping that using
this feature will reduce the high sensitivity near sources and receivers.

I turned on the flag in the code to output the approximate Hessian, so
for my (acoustic) simulations I now have the binary output
proc*_hess_acoustic_kernel.bin, an array of the same size as the
material values.  I had thought that I simply needed to multiply (or
divide?) the approximate Hessian into the corresponding
proc*_alpha_acoustic_kernel.bin event kernel, but the values I see are
strange in either case.

Thank you for your help,
Alan Schiemenz