adequate measure against damage and may in fact achieve the exact opposite. Because building
codes are designed to resist a disaster up to a certain magnitude, events exceeding that
magnitude may cause a catastrophe. However, people often do not realize this and are given a
false sense of security by these building codes (Nelson & French 2002).
To ensure a safety standard for all buildings, all structures built before the implementation of
the building design codes should be retrofitted if necessary. As with the building design codes
themselves the contents of a retrofitting code depend on the hazard. Some retrofitting
improvements are major construction activities, others are relatively easy and inexpensive
(Beatley & Berke 1992). In general, hazard proofing a building is cheaper if done when
constructing the building. Retrofitting an existing building is usually much more expensive.
The most vulnerable buildings are un-reinforced masonry, and buildings with a weak first floor
(for example multi-family homes with numerous garages on ground level). These two
categories of buildings most often need expensive retrofitting (Cutcliffe 2000). The high costs
of retrofitting can sometimes be problematic: since retrofitting usually involves considerable
expenses for the owner, it is often decided that it is cheaper to demolish the building. If the
owner decides to retrofit, rents often increase (Beatley & Berke 1992).
2.2.2 Non-structural mitigation
Non-structural mitigation includes all land-use regulations that aim to divert (certain types of)
development away from the most hazardous areas (Berke 1994). Zoning is the most used tool
because it is inexpensive and effective (Burby e.a. 1999). However, local governments are
often reluctant to restrict development as they fear the financial consequences of such a
decision. Research by Nelson & French (2002) provides evidence that local land use plans and
zoning regulations are effective in mitigating natural hazard damage, but that a higher level
mandate is necessary to force local governments to do so. Godschalk e.a. (1999) too recognize
the advantages of high quality land-use plans and zoning regulations. The effectiveness of
these non-structural measures combined with relatively low costs make them an ideal
mitigation tool.
Sometimes local authorities will purchase high-risk land and reserve it for parklands and other
low-risk uses. If necessary, existing structures will be demolished or relocated. This method of
acquisition is a much-belauded mitigation tool among planning experts (Godschalk e.a. 1999,
Beatley & Berke 1992, Nelson & French 2002). However, the acquisition of all high-risk land