This data was submitted by Nancy Saltzman ( saltzman@ncsc.org )

The data is in AVS UCD format.

Enjoy -

Terry

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Terry Myerson
International AVS Center
North Carolina Supercomputing Center
avs@ncsc.org



     This ucd data contains the finite element model of a sedimentary basin.
Three dimensional displacements are given at the nodes.  Each file
contains the normalized displacements describing motion of one mode of
oscillation, whose frequency is indicated in the file name (eg. 27886as.inp
has frequency .27866).  The basin model is half-ellipsoidal in shape.  The
bottom curved surface models a subterranean rock interface and is required to
have no displacement, while the top flat surface of the model is a free surface
corresponding to the ground surface.  Only one quarter of the basin is modelled
since it is sufficient to obtain solution for the full basin due to symmetries
in the basin shape.  Accordingly, modes are classified as 'sa', 'ss', 'as',
and 'aa', where the first letter refers to motion of the vertical plane
containing the long horizontal axis of the ellipsoid and the second refers to
motion of the vertical plane containing the short horizontal axis.  In this
notation 'a' indicates 'antisymmetric' motion constrained to be strictly
perpendicular to the plane and 's' indicates 'symmetric' motion constrained to
be entirely in the plane.  This type of data is of interest to seismologists
and earthquake engineers because sedimentary basins which are filled with soft
sediments and surrounded by hard rock trap earthquake waves within the basins,
causing high amplitude, long duration, near mono-frequency ground motions that
can be devastating to structures that may have similar natural frequencies.
Thus visualization of ground motion (motion at the free surface) is a primary
objective.  Important characteristics affecting earthquake hazard assessment
are ground locations of relatively large and very small displacement
amplitudes, and the direction of motion polarization at different ground
locations.   Characteristics of subterranean motion, particularly locations of
nodal surfaces where displacement is zero, are important for physical insight
into the mechanism of resonant motion.