Previous research has shown a post-disaster increase of Gender Based Violence [GBV], suggesting a need for further investigation of the phenomena and its causes. This research draws together a wide-ranging collection of secondary data sets concerning disasters and gender based violence. It analyses the social environment in post-disaster settings that breeds an increase in GBV with focus on Sexual Gender Based Violence[SGBV] and Intra Personal Violence [IPV]. Through a comparison of two case studies: (a) post-earthquake Haiti and (b) post-hurricane Katrina. The cases are analysed through an analytical framework constructed out of three theories, Eco-feminism, Hyper-masculinity and Situational Theory, which together could give a trustworthy explanation of the phenomena. The findings show that similar factors were prevalent in both cases, and in turn provides insights for the abductively derived framework that relates the causal mechanisms behind the phenomena of post-disaster gender-based violence, building on the commonalities between social environments and structures in the cases. In particular, it was found that a patriarchal root structure and high rates of frustration both provided explanatory causal mechanisms for increased GBV. Though changes in environments can affect the prevalence of GBV as it can provide easier access of victims and lower the risk of penalties in relation to the crimes. In order to address GBV associated with future disasters, post-disaster plans need to adapt a gender mainstreamed approach with focus on safe housing and rapid rebuilding processes for the grass root level.