Introduction: planning to mitigate hazards

Efforts to plan for disaster mitigation have increasingly gained attention only recently. Even countries that have a reputation for progressive mitigation efforts only implemented systems that urge planning to play a central role in disaster mitigation within the past few decades. Examples include the US Federal Disaster Mitigation Act 2000 (DMA 2000), Indonesia's 2007 Disaster Management Law (Tentang Penanggulangan Bencana) and the 2007 European Commission's directive on the assessment and management of flood risk that is legally enforceable and conceptually the closest to managing risk through land use control. Japan has a longer history of possessing disaster risk reduction systems that include laws and legislation related to spatial control, starting with the modern Disaster Countermeasures Basic Act 1961. Otherwise, mitigation concepts – proactively taking measures to reduce possible disaster impacts – were not centralised in disaster management schemes. In the US, for example, disaster relief was the major response to disasters until the latter half of the 20th century, and was managed mainly by humanitarian and volunteer organisations (Rubin, 2007).

Since the mitigation concept became more widespread, planners and policymakers have largely emphasised this phase among others of disaster management – that is, preparedness, response and recovery – in planning practice. It addresses the importance of evaluating different types of hazards, including seismic (see Olshansky, 2001; Nelson and French, 2002), floods (see Burby and French, 1981; Morris, 1997) and landslides (see Varnes, 1984; Fella et al, 2008). Studies on mitigation via land use control have also interested planners for quite some time (Olshansky and Chang, 2009). Although empirical research on this topic is sparse, disaster mitigation efforts have proven to be beneficial if enforced appropriately at the local government level (Schwab et al, 1998). For instance, studies found that planning measures taken at the local governmental level in Los Angeles prior to the Northridge Earthquake of 1994 significantly contributed to mitigating losses. In particular, the culture of information sharing via hazard maps created an environment that made it easier to advance engineering measures, and land use plans prepared with appropriate mitigation measures contributed to reducing damage (Olshansky, 2001; Nelson and French, 2002).