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Earthquake-Associated Deaths -- California

On October 17, 1989, at 5:04 p.m. Pacific daylight time, an earthquake registering 7.1 on the Richter scale, with an epicenter in the Loma Prieta section of the San Andreas fault, occurred in northern California (Figure 1). The earthquake released seismic energy equivalent to a 7-megaton nuclear explosion, generated lateral acceleration forces exceeding 60% of the earth's gravitational pull, and caused an estimated $5.6 billion in property damage (excluding damage to highways, bridges, and state office buildings) in the seven disaster counties (Alameda, Monterey, San Benito, San Francisco, San Mateo, Santa Clara, and Santa Cruz (combined January 1, 1989, resident population approximately 4,672,300) (1)).

Using contact information in Medical Examiner and Coroner Jurisdictions in the United States (2), public health officials asked county medical examiners and coroners (ME/Cs) in the disaster counties to report 1) the number of earthquake-related deaths investigated in their jurisdictions from October 17 through October 31 and 2) information about the demographic characteristics, cause, and circumstance of each death. There is no universally accepted definition of an "earthquake-related death"; for this report, the determination was made by each county ME/C.

County ME/Cs in the disaster area reported 63 earthquake-related deaths (60 directly related and three indirectly related). Of the 60 directly related deaths, 57 (95%) resulted from injuries sustained within 2 minutes of the earthquake; three resulted from injuries sustained within 8 hours of the earthquake (Table 1). Three deaths occurring within 24 hours of the earthquake were indirectly related (Table 1). The highest county-specific mortality rate for all earthquake-related deaths occurred in Alameda County (3.4 per 100,000 population) (Figure 1, Table 2). Reported by: DP Cain, CC Plummer, Sheriff-Coroners Office, Alameda County; DB Cook, Sheriff-Coroners Office, Monterey County; HS Nyland, Sheriff-Coroners Office, San Benito County; JE Surdyka, BG Stephens, MD, Medical Examiner-Coroners Office, San Francisco County; PB Jensen, Coroners Office, San Mateo County; NL Gossett, JE Hauser, MD, Medical Examiner-Coroners Office, Santa Clara County; AF Noren, Sheriff-Coroners Office, Santa Cruz County; SJ Martel, PhD, Earth Sciences Div, Lawrence Berkeley Laboratory, Univ of California, Berkeley; TR Toppozada, PhD, Div of Mines and Geology, California Dept of Conservation; RB Trent, PhD, Emergency Preparedness and Injury Control Program, JW Stratton, MD, Hazard Evaluation Section, DC Mortenson, RA Kreutzer, MD, LR Goldman, MD, Environmental Epidemiology and Toxicology Section, KH Acree, MD, DO Lyman, MD, Preventive Medical Svcs Div, KW Kizer, MD, Director, California Dept of Health Svcs. Div of Field Svcs, Epidemiology Program Office; Div of Environmental Hazards and Health Effects, Center for Environmental Health and Injury Control, CDC.

Editorial Note

Editorial Note: An earthquake's magnitude (measured with the logarithmic Richter scale (3)) is one of the most important factors influencing the extent of earthquake-related destruction and mortality. Other contributing factors include population density, proximity to the epicenter, local geology, building codes and compliance with them, building materials, number of stories and age of structures, and capabilities of local emergency medical services (4).

As with Hurricane Hugo (5,6), ME/Cs, who are responsible for investigating deaths related to trauma and violence, rapidly determined the extent of earthquake-related mortality and provided detailed information on circumstances of death, as well as demographic information on decedents. Mortality associated with the California earthquake was lower than for recent earthquakes of similar magnitude. Potentially responsible factors include local geology and building patterns; incorporation of aseismic (earthquake-resistant) engineering features in buildings in the densely populated downtown sections of Oakland, San Francisco, and San Jose; and absence of major, widespread fires following the earthquake. The lower mortality in the recent earthquake also contrasts with the mortality in the 1906 earthquake in San Francisco (approximately 667 deaths per 100,000 population) (7).

The California Emergency Medical Service Authority and the California Department of Health Services, in cooperation with the Region IX Office of the Public Health Service and CDC, have developed comprehensive plans for an emergency medical/ public health response to a catastrophic earthquake. These plans established state and federal support mechanisms to enhance local governments' ability to respond. This support includes the National Disaster Medical System; coordination of procurement and distribution of medical supplies; provision of medical personnel, equipment, and public health services; and, if necessary, establishment of field hospitals and evacuation of casualties.

Following the earthquake, initial reports indicate that local medical and public health resources were generally adequate. State and federal assistance was provided as needed; however, the catastrophic earthquake response plans were not activated. Local, state, and federal agencies are reviewing the response to this event; the California Department of Health Services is investigating additional public health aspects of the earthquake, including cause-specific morbidity and mortality, public preparedness, and the adequacy of emergency response.


  1. Department of Finance. Population estimates of California cities and counties: January 1, 1988-January 1, 1989. Sacramento: Department of Finance, 1989. (Report 89 E-1).

  2. Parrish RG, Ing R. Medical examiner and coroner jurisdictions in the United States. Colorado Springs, Colorado: American Academy of Forensic Sciences, 1988.

  3. California Department of Conservation, Division of Mines and Geology. How earthquakes are measured. Calif Geol 1979;32(Feb.):35-7.

  4. Stratton J. Earthquakes. In: Gregg MB, ed. Public health consequences of disasters. Atlanta: US Department of Health and Human Services, Public Health Service (in press).

  5. CDC. Deaths associated with Hurricane Hugo--Puerto Rico. MMWR 1989;38:680-2.

  6. CDC. Medical examiner/coroner reports of deaths associated with Hurricane Hugo--South Carolina. MMWR 1989;38:754,759-62.

  7. Hansen GC. San Francisco numbers game. Calif Geol 1987;40(Dec.):271-4.

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