[CIG-SEISMO] The strain

[Zhang Lingyun]

Dear Professor:

   I'm a graduate student from University of Chinese Academy of Sciences(The
institute of the geodesy and geophysics, CAS, WuHan). I was once taught by
Sun Wenke, whose supervisor is Okubo. I'm now working in Professor Sidao Ni'
group to explore the mysteries of the deep interior earth. I've read a lot
of papers about the normal modes, the kernel to this problem is to solve the
DY/DX=A(x)Y equations. John Woodhouse[1988] proposed a ,method -minor
vectors. Although it seems have a huge computation, in fact, stable. Based
on the theory, the one dimension earth model software Mineos raised, the
open fortran code helped me to develop my programming skills. The purpose is
to generate synthetic seismogram by summing every mode computed for given
frequency.

  There is a big differences between the synthetic and real seismic data.
Interestingly, it is the difference that we should focus on. It can reflect
and constrain the true structure. Consequently, the importance of the
observation become more and more important. In contrast to inertial
seismometers, which respond to ground acceleration and thus to the second
derivative of the displacement with respect to time, strain-seismometers,
commonlytermed extensometers or strainmeters, respond to the spatial
derivatives of the displacement field of the incoming seismic wave or in
other words, to a combination of the components of the wave's strain tensor.
For this reason, strainmeters are inherently instruments which are sensitive
to phenomena with "zero" (i.e., very low) frequency and thus particularly
suitable for studying crustal deformations due to solid Earth tides and
normal mode oscillations of the Earth.  

I was deeply impressed on by your intensive and extensive study.
Unfortunately, there is a block on my way. As mentioned above, the
strainmeters is so significant in getting the real data, but it seems that I
can't get a software to generate the synthetic liner data, someone had told
me that I could use the Mineos software and extract the strain components
from it, I am wondering whether it need external function or program for
that purpose. Is it open to me? It is a great honor to receive your help.

I am looking forward your response. Wish you happy everyday

 

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