Area based triggers denote notifications being generated if a mobile client changes its spatial relation to a defined area, e.g. if it enters or leaves it. By these triggers, new valuable services can be provided for mobile users. One of the main challenges is to design a suited approach for the computation of the triggers based on the defined areas and the current whereabouts of the mobile clients. With a rising number of areas and participants of these services, the need for a scalable solution to process the triggers emerges. This paper examines a new approach for the distributed, hierarchical processing of area based triggers based on the aggregation and segregation of both triggers and the setup messages requesting the services in a carrier access network. We investigate the signaling effort and computational complexity of the approach based on the required effort for an emerging position update of a mobile client in the network. The results are compared analytically with two other approaches, a centralized and a hierarchical one. Our analysis shows that our approach leads to a superior performance in terms of the effort for signaling and computation.