With the increasing frequency of natural disasters and intentional attacks that challenge telecommunication networks, vulnerability to cascading and regional-correlated challenges is escalating. Given the high complexity and large traffic load of optical networks, these correlated challenges cause substantial damage to reliable network communication. In this paper, we propose a network vulnerability identification mechanism and study different vulnerability scales using real-world optical network data. We further propose geographical diversity and incorporate it into a new graph resilience metric cTGGD (compensated Total Geographical Graph Diversity), which is capable of characterising and differentiating resiliency levels among different optical fibre networks. It is shown to be an effective resilience level indicator under regional network challenges or attacks. We further propose two heuristics for solving the path geodiverse problem (PGD) in which the calculation of a number of geographically separated paths is required. Geodiverse paths can be used to circumvent physical challenges such as large-scale disasters in telecommunication networks. We present the GeoDivRP routing protocol with two new routing heuristics implemented, which provides the end nodes with multiple geographically diverse paths. Our protocol demonstrates better performance compared to OSPF when the network is subject to area-based challenges. We have analysed the mechanism by which the attackers could use to maximise the attack impact with a limited budget and demonstrate the effectiveness of restoration plans.