  A random fuse network, or equivalently a two-dimensional spring network with
quenched disorder, is subjected to a constant load and thermal noise, and
studied by means of numerical simulations. Rupture is thermally activated and
the lifetime follows an Arrhenius law where the energy barrier is reduced by
disorder. Due to the non-homogeneous distribution of forces from the stress
concentration at microcrack tips, spatial correlations between rupture events
appear, but they do not affect the energy barrier's dependence on the disorder;
they affect only the coupling between the disorder and the applied load.
