We consider a three-dimensional elastic body with a plane fault under a slip-weakening friction. The fault has
ϵ
\epsilon
-periodically distributed holes, called (small-scale) barriers. This problem arises in the modeling of the earthquake nucleation on a large-scale fault. In each
ϵ
\epsilon
-square of the
ϵ
\epsilon
-lattice on the fault plane, the friction contact is considered outside an open set
T
ϵ
T_\epsilon
(small-scale barrier) of size
r
ϵ
>
ϵ
r_\epsilon >\epsilon
, compactly inclosed in the
ϵ
\epsilon
-square. The solution of each
ϵ
\epsilon
-problem is found as local minima for an energy with both bulk and surface terms. The first eigenvalue of a symmetric and compact operator
K
ϵ
K^\epsilon
provides information about the stability of the solution. Using
Γ
\Gamma
-convergence techniques, we study the asymptotic behavior as
ϵ
\epsilon
tends to
0
0
for the friction contact problem. Depending on the values of
c
=:
lim
ϵ
→
0
r
ϵ
/
ϵ
2
c=:\lim _{\epsilon \rightarrow 0} r_\epsilon /\epsilon ^2
we obtain different limit problems. The asymptotic analysis for the associated spectral problem is performed using
G
G
-convergence for the sequence of operators
K
ϵ
K^\epsilon
. The limits of the eigenvalue sequences and the associated eigenvectors are eigenvalues and respectively eigenvectors of a limit operator. From the physical point of view our result can be interpreted as follows: i) if the barriers are too large (i.e.
c
=
∞
c = \infty
), then the fault is locked (no slip), ii) if
c
>
0
c >0
, then the fault behaves as a fault under a slip-dependent friction. The slip weakening rate of the equivalent fault is smaller than the undisturbed fault. Since the limit slip-weakening rate may be negative, a slip-hardening effect can also be expected. iii) if the barriers are too small (i.e.
c
=
0
c=0
), then the presence of the barriers does not affect the friction law on the limit fault.