Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Seismic motion in urban sites consisting of blocks in welded contact
  with a soft layer overlying a hard half space: I. Finite set of blocks   We address the problem of the response to a seismic wave of an urban site
consisting of $N$ non-identical, non-equispaced blocks overlying a soft layer
underlain by a hard substratum. The results of a theoretical analysis,
appealing to a space-frequency mode-matching (MM) technique, are compared to
those obtained by a space-time finite element (FE) technique. The two methods
are shown to give rise to the same prediction of the seismic response for N=1
and N=2 blocks. The mechanism of the interaction between blocks and the ground,
as well as that of the mutual interaction between blocks, are studied. It is
shown that the presence of a small number of blocks modifies the seismic
disturbance in a manner which evokes qualitatively, but not quantitatively,
what was observed during the 1985 Michoacan earthquake in Mexico City.
Disturbances at a much greater level, induced by a large number of blocks (in
fact, a periodic set) are studied in the companion paper.

31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph