The management of disasters has given increasing attention to systemic risks over the past two decades. This term refers to the potential chain reactions triggered by one or more disasters across social systems, impacting sectors such as the economy, communication, transportation, and healthcare. The catastrophic 2004 Indian Ocean tsunami, which resulted in massive casualties and economic losses across South Asia, serves as a prime example of systemic risks. This chapter delves into the theory and historical development of systemic risks, highlighting their main manifestations during the Indian Ocean tsunami. It also explores the evolution and current shortcomings of systemic risk management since the event. The chapter’s objective is to enhance the resilience of societies against complex disasters from a systemic risk perspective and to provide a reference framework for future developments in systemic risk management