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Background: Earthquakes cause thousands of deaths worldwide every year, and systematic study of the causes of these deaths can lead to their prevention. Few studies have examined how multiple types of risk factors are related to physical injury during an earthquake. Methods: A population based case-control study was conducted to examine how individual characteristics, building characteristics, and seismic features of the 1994 Northridge, California, earthquake contributed to physical injury. Cases included fatal and hospital-admitted injuries caused by the earthquake. Controls were drawn from a population based phone survey of county residents. Cases were individually matched to two sets of controls: one matched by age and gender and one matched by location at the time of the earthquake. Results: Individuals over age 65 had 2.9 times the risk of injury as younger people (95% confidence interval (CI) 1.2 to 7.4) and women had a 2.4 times greater risk than men (95% CI 1.2 to 5.1). Location in multiple unit residential and commercial structures each led to increased injury risk compared with single unit residential structures, but the exact estimate varied depending on the control group used. With every increase in ground motion of 10%g, injury risk increased 2.2 times (95% CI 1.6 to 3.3). Conclusions: Controlling for other factors, it was found that individual, building, and seismic characteristics were independently predictive of increased injury risk. Prevention and preparedness efforts should focus on each of these as potential points of intervention.

Part I of this two-part paper provides an overview of the HAZUS-MH Flood Model and a discussion of its capabilities for characterizing riverine and coastal flooding hazard. Included is a discussion of the Flood Information Tool, which permits rapid analysis of a wide variety of stream discharge data and topographic mapping to determine flood-frequencies over entire floodplains. Part II reports on the damage and loss estimation capability of the Flood Model, which includes a library of more than 900 damage curves for use in estimating damage to various types of buildings and infrastructure. Based on estimated property damage, the model estimates shelter needs and direct and indirect economic losses arising from floods. Analyses for the benefits of flood warning, levees, structural elevation, and flood mapping restudies are examples of analyses that can be performed with the Flood Model.

This paper presents interim results of an ongoing study of building damage and losses likely to occur due to a repeat of the 1906 San Francisco earthquake, using the HAZUS technology. Recent work by Boatwright et. al. (2006) provides MMI-based ShakeMap estimates of spectral response accelerations derived from observations of intensities in the 1906 San Francisco earthquake. This paper calculates damage and loss estimates using those estimated ground motions, then compares the resulting estimates with those calculated using a method parallel with that of current seismic provisions of building codes for a magnitude M7.9 event on the San Andreas Fault, and contrasts differences in damage and loss patterns for these two scenarios. The study region of interest comprises 19 counties of the greater San Francisco Bay Area and adjacent areas of Northern California, covering 24,000 square miles, with a population of more than ten million people and about $1.5 trillion of building and contents exposure. The majority of this property and population is within 40 km (25 miles) of the San Andreas Fault. The current population of this Northern California region is about ten times what it was in 1906, and the replacement value of buildings is about 500 times greater. Despite improvements in building codes and construction practices, the growth of the region over the past 100 years causes the range of estimated fatalities, approximately 800–3,400 depending on time of day and other variables, to be comparable to what it was in 1906. The forecast property loss to buildings for a repeat of the 1906 earthquake is in the range of approximately $90–120 billion; 7,000–10,000 commercial buildings in the region are estimated to be closed due to serious damage; and about 160,000–250,000 households calculated to be displaced from damaged residences. Losses due to fire following earthquake, as well as losses to utility and transportation systems, would be in addition to these estimates.

The Northridge earthquake will long be remembered for the unprecedented losses incurred as a result of a moderate-size event in a suburban area of Los Angeles. Current documented costs indicate that this event is the costliest disaster in U.S. history. Although it is difficult to estimate the full cost of this event, it is quite possible that total losses, excluding indirect effects, could reach as much as $40 billion. This would make the Northridge earthquake less severe than the Kobe event, which occurred exactly one year after the Northridge earthquake, but adds a bit of realism that a Kobe-type disaster is possible in the U.S. This paper attempts to put into perspective the direct capital losses associated with the Northridge earthquake. In doing so, we introduce the concept of hidden and/or undocumented costs that could double current estimates. In addition, we present the notion that a final estimate of loss may be impossible to achieve, although costs do begin to level off two years after the earthquake. Finally, we attempt to reconcile apparent differences between loss totals for two databases tracking similar information.

In 2008, an earthquake-planning scenario document was released by the U.S. Geological Survey (USGS) and California Geological Survey that hypothesizes the occurrence and effects of a Mw7.8 earthquake on the southern San Andreas Fault. It was created by more than 300 scientists and engineers. Fault offsets reach 13 m and up to 8 m at lifeline crossings. Physics-based modeling was used to generate maps of shaking intensity, with peak ground velocities of 3 m/sec near the fault and exceeding 0.5 m/sec over 10,000 km2. A custom HAZUS®MH analysis and 18 special studies were performed to characterize the effects of the earthquake on the built environment. The scenario posits 1,800 deaths and 53,000 injuries requiring emergency room care. Approximately 1,600 fires are ignited, resulting in the destruction of 200 million square feet of the building stock, the equivalent of 133,000 single-family homes. Fire contributes $87 billion in property and business interruption loss, out of the total $191 billion in economic loss, with most of the rest coming from shake-related building and content damage ($46 billion) and business interruption loss from water outages ($24 billion). Emergency response activities are depicted in detail, in an innovative grid showing activities versus time, a new format introduced in this study.

At the time of the Northridge earthquake, a number of new technologies, including real-time availability of earthquake source data, improved loss estimation techniques, Geographic Information Systems and various satellite-based monitoring systems, were either available or under consideration as emergency management resources. The potential benefits from these technologies for earthquake hazard mitigation, response and recovery, however, were largely conceptual. One of the major lessons learned from the January 17, 1994 earthquake was that these technologies could confer significant advantages in understanding and managing a major disaster, and that their integration would contribute a significant additional increment of utility. In the two and half years since the Northridge earthquake, important strides have been taken toward the integration of relatively discrete technologies in a system which provides real-time estimates of regional damage, losses and population impacts. This paper will describe the development, operation and application of the first real-time loss estimation system to be utilized by an emergency services organization.