Earthquake Risk Reduction in the Western United States

Among the western states, including Hawaii and Alaska, 52 million people are exposed to seismic hazards. Despite the risks posed by earthquakes—for some states borne out by costly occurrences—there is not much of a public constituency pushing for efforts to avert earthquake losses. The risks are not mass public issues that compel groups to the steps of state capitols or to city halls demanding to be saved. The lack of a public constituency, coupled with varied concerns of local officials about the risks, creates uncertain incentives for local governments to be proactive in reducing these risks.

This article reports the results of a study of risk-reduction practices that was carried out to gain a better understanding of the variability in the efforts of local governments to reduce earthquake risks, and of the factors that influence their actions. The central issues that emerged are the willingness and capacity of governments to adopt and enforce earthquake risk-reduction measures. To clarify these issues data were analyzed concerning the efforts of 258 local governments in 11 western states. These data are drawn from a national survey of city and county enforcement of building codes undertaken in 1995. (The more general findings from that study are reported by Burby, May, and Paterson (1998), Burby and May (1999), and May (1997).) For this research, western states were selected for which five or more jurisdictions were part of the original sample (thereby eliminating Colorado and Hawaii). The response rate to the survey in the remaining states was 76%, which varied from a low of 63% in Alaska to a high of 92% in Idaho. A statistically valid profile was developed for jurisdictions in the western states by weighting the sample data to reflect each state's proportion of the total number of localities in the western United States.

Willingness and Capacity to Enforce Seismic Provisions of Codes

An important consideration for the future development of codes in general and of performance-based codes in particular is the willingness and capacity of local governments to enforce the seismic provisions of building codes. Requirements vary in the western states concerning code enforcement (see below), for which the Uniform Building Code is the common reference for states that either mandate or otherwise specify provisions. This study analyzed the priority that local governments attach to the enforcement of seismic provisions and how they handle the review of plans, as reported in the responses to the survey.

The reports of building officials on the priority assigned to the enforcement of seismic provisions provides a mixed but largely positive picture. As shown in table 1, about 50% of local building departments report assigning a high priority (5 on a scale of 1 to 5). More than 80% assigned a high or very high priority to this function. Furthermore, a substantial percentage of building officials report increasing the enforcement priority in recent years. A less favorable finding is the substantial difference between the priority assigned by officials in high hazard areas (peak ground acceleration (PGA) greater than 0.20 g) and those in moderate to low areas—recognizing the difficulty of making this classification. This finding is troubling given the potential for earthquake damage in moderately seismic areas. (Only 24% of the localities in the sample have PGA values of less than 0.10 g, while 30% have values between 0.10–0.20 g.)

Some understanding of the capacity to enforce seismic provisions can be gained by considering how review of the seismic elements of plans is handled (see the lower half of table 1). For the majority of localities, regardless of the earthquake hazard, the seismic review is conducted in-house. However, there is a notable difference in the percentage of jurisdictions that conduct a detailed review of the seismic components (versus selective reviews). The difference in the review process affects the variability in the willingness and ability to enforce seismic provisions.

Table 1

State Regulatory Roles

The role that states take is an important aspect of examining the variation in the earthquake risk-reduction efforts of local governments. To clarify this, the 11 states in the study were classified into three categories according to their regulatory roles. The first category contains California, the aggressive state, which stands alone in the extent of state mandates for local government action. The second category includes the attentive states, those that have strong state building codes with required local enforcement of seismic provisions. The third category comprises the minimalist states, which make provisions for, but do not necessarily require, local enforcement of seismic provisions. The classification system was used to consider the differences among states in the percentage of localities that report high priority for enforcement of seismic provisions, and differences among localities in the adoption of local seismic regulations. The latter is measured as the number of five potential regulatory requirements adopted by each jurisdiction (special inspection, seismic reinforcement of existing structures, securing of water heaters, restrictions on development in fault zones or areas with unstable soils, and retrofitting of earthquake-prone structures).

The differences in local governmental risk-reduction efforts among these three categories of states are summarized in table 2. Here it can be seen that the variation in effort among localities generally mirrors differences in state roles. Localities in California stand out from those in both the attentive and minimalist states with respect to both measures of local regulatory efforts. In the attentive states, local regulations average more than five times those of minimalist states, and nearly twice as many localities place a high priority on the enforcement of seismic provisions of building codes than do the localities in minimalist states. The differences in local regulatory actions also reflect variation in the extent of earthquake hazards among states. As shown in the right column of table 2, the earthquake hazard for localities differs among the three categories of states.

Table 2

To determine the variation in the earthquake risk-reduction efforts of local governments, multivariate statistical analyses were conducted that considered the differences in state roles, the overall problem (earthquake hazards and prior disaster experience), and political and economic considerations. The state regulatory role accounts for 22% of the explained variation in the number of local seismic regulations adopted and more than 7% of the explained variation in the enforcement priority for the seismic provisions of building codes. The extent of the problem accounts for 8% of the explained variation in the number of local seismic regulations and 13% of the explained variation in the enforcement priority. The adoption of local seismic regulations is strongly influenced by the frequency of damaging earthquakes, while the extent of the seismic hazard has a noteworthy influence on the priority given to enforcing seismic provisions. Economic considerations account for 9% of the explained variation in local adoption of seismic regulations. In keeping with the notion that earthquake risks are not mass public issues, political considerations account for less than 2% of the explained variation in the number of local seismic regulations and a negligible portion of the variation in the priority for enforcing the seismic provisions of building codes.

Conclusion

The findings concerning the earthquake risk-reduction efforts of local governments in 11 western states can be interpreted in either an optimistic or pessimistic light. Caution must be exercised in interpreting the regulatory efforts reported by local governments, and the general categories of items examined. Nonetheless, broad patterns are evident from these data. The positive points are that building officials appear to be responsive to the extent of earthquake hazard and that many local governments in high-hazard areas are serious about addressing the risks. The more pessimistic perspective relates to the wide variation in risk-reduction abilities and actions, both among and within states, even when accounting for the extent of earthquake hazard. A key challenge is to address the capabilities and commitment of those jurisdictions that lag in risk-reduction efforts.

Acknowledgments

Financial support for this research was provided by the Pacific Earthquake Engineering Research Center. The survey data that we draw upon were collected by Raymond J. Burby and Peter J. May under a project funded by a National Science Foundation grant to the University of New Orleans. We thank Raymond Burby for his assistance. Our findings are not necessarily endorsed by the National Science Foundation or the Pacific Earthquake Engineering Research Center.

Peter J. May, Professor
and
T. Jens Feeley, Ph.D. student
Department of Political Science
University of Washington
References
Burby, Raymond J., and Peter J. May. 1999. Making building codes an effective tool for earthquake hazard mitigation. Environmental Hazards: Global Environmental Change, Part B. 1 (fall): in press.

Burby, Raymond J., Peter J. May, and Robert C. Paterson. 1998. Improving compliance with regulations: Choices and outcomes for local government. J. of the American Planning Ass'n. 64 (3): 324–34.

May, Peter J. 1997. State regulatory roles: Choices in the regulation of building safety. State and Local Government Rev. 29 (spring): 70–80.