Academic journal article Bulletin of the World Health Organization

Risk Factors for Injuries Due to the 1990 Earthquake in Luzon, Philippines

Academic journal article Bulletin of the World Health Organization

Risk Factors for Injuries Due to the 1990 Earthquake in Luzon, Philippines

Article excerpt

On 16 July 1990, an earthquake measuring 7.7 on the Richter scale struck the island of Luzon, Philippines. A case-control study was carried out to identify the risk factors for earthquake-related injuries and at the same time observations were made on the rescue efforts.

Being hit by falling objects was the leading cause of injury (34%). Those injured during the tremor were more likely to have been inside buildings constructed of concrete or mixed materials (odds ratio, 2.6; 95% confidence interval (CI), 1.7-4.1) and to have been on the middle floors of multistorey buildings (odds ratio, 3.4; 95% CI, 2.2-5.5). Leaving a building during the earthquake was a protective behaviour (odds ratio, 0.3; 95% CI, 0.2-0.8). Of the 235 survivors who were trapped and rescued alive from the rubble, 99% were rescued within 48 hours of the impact of the tremor.

These findings should prove useful in developing seismic safety codes. People should be taught proper evasive actions to take during earthquakes, and training in basic first aid and methods of rescue should be an integral part of community preparedness programmes.


On 16 July 1990, at 16h30, an earthquake of magnitude 7.7 on the Richter scale struck northern and central Luzon Island in the Philippines, resulting in substantial morbidity and mortality as well as wide-spread damage. Officially, 1283 deaths and 2786 injured survivors were reported. Many more injuries and deaths were probably not recorded, especially in remote mountainous areas where landslides occurred. Among the areas severely affected were the mountain city of Baguio, in Benguet, the coastal areas in La Union, and the provinces of Nueva Ecija and Nueva Vizcaya (Fig. 1).

Teams from the Field Epidemiology Training Program (FETP), Philippines Department of Health, in the course of relief efforts, carried out a study to determine the risk factors for injuries and deaths. Observations were made also on the rescue and medical efforts. Knowledge about the factors associated with death and injuries in earthquakes should prove useful in formulating appropriate public health responses to similar disasters.

Subjects and methods

An unmatched case-control study was performed in Baguio, La Union, Nueva Ecija, and Nueva Vizcaya 1-2 weeks after the earthquake. Cases were persons (dead or alive) who sustained physical injuries during the earthquake of 16 July or its aftershocks; controls were uninjured persons who were in the same neighbourhood as cases during the earthquake or its aftershocks. The cases were identified from hospital records or the Department of Social Welfare and Development lists, while the controls were uninjured family members of cases or persons in refugee centres.

Interviews were conducted using a questionnaire that covered sociodemographic information such as age and gender; location during the earthquake; behaviour during the earthquake; causes and types of injuries; rescue experiences; and medical interventions received. All living subjects, except young children, were interviewed personally by the FETP team. Information about the young children was obtained from the adults who were with them during the earthquake. Fatalities were included in the study only when first-hand eyewitness accounts could be obtained from survivors or rescuers.

The results were analysed using the Epi Info version 5 computer program (Centers for Disease Control, Atlanta, GA, USA); [chi.sup.2] tests were calculated and Cornfield 95% confidence limits were determined for the odds ratios.


There were a total of 1104 respondents. Of these, 363 (33%) were cases, 68 (19%) of whom died; the remaining 741 (67%) were uninjured controls.

Sociodemographic profile

Age and gender distributions of cases and controls were similar. The age of cases ranged from 3 months to 92 years (mean, 26 years, while that of controls was 2 months to 81 years (mean, 26 years). …

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