Prior to the question about informal knowledge, my previous PhD thesis was determined how tacit knowledge help organization effectively codified into specific knowledge in advancing organization efficiency. I proposed innovation capacity that exhibit from one generation to another particularly in those century old enterprises carried out with branded production such as Lego, Ikea, Suzuki, Tata, Samsung etc successfully improve in organizational resilience. I suggest few link for you to browse through about informal knowledge or so called tacit knowledge.
1. Collis, David J. "Research note: how valuable are organizational capabilities?." Strategic management journal 15.S1 (1994): 143-152.
2. Miller, K. D., Zhao, M., & Calantone, R. J. (2006). Adding interpersonal learning and tacit knowledge to March's exploration-exploitation model. Academy of Management Journal, 49(4), 709-722.
3. Cook, S. D., & Brown, J. S. (1999). Bridging epistemologies: The generative dance between organizational knowledge and organizational knowing. Organization science, 10(4), 381-400.
@John, great response you provided here, but I am curious to know from you if informal knowledge is synonymous to tacit or implicit knowledge, because I think otherwise. On the original question, informal knowledge is surely interrelated with organizational resilience,,,however, such interrelation would be positive when the owners of such knowledge are willing and disposed to share such knowledge. A paper on employees' altruism and organizational adaption by Jaja and Gabriel (2014) can be useful. Because, sharing informal knowledge can be seen as an altruistic behavior and such behaviour was found as positively associated with adaptation which is a measure of organizational resilience.