This paper proposes to use CR-prolog to add planning capabilities to a Geographical Information System. CR-rules can restore the consistency of a program giving the diagnosis of possible causes of failure in a plan. In this paper, we give an additional use for CR-rules: we propose to use CR-rules to obtain an alternative plan in case of the ideal plan fails. They not only restore consistency and give the diagnosis they also give support to define an alternative plan. In particular, we show the use of CR-rules in a situation related to the risk zone of volvano Popocatepetl. We show by means of an example how to obtain alternative evacuation routes using CR-rules.