—from Epidemiological Bulletin, Vol. 22 No. 1, March 2001—
Earthquakes in El Salvador
On January 13, 2001, El Salvador was ravaged by an earthquake with a magnitude of 7.6 on the Richter Scale, located at longitude 88°46’W and latitude 12°52’N. The epicenter was located off the Pacific Coast of El Salvador, 65 Km south of Usulután, at a depth of 60 Km (Figure 1). This massive earthquake originated in an inclined rupture zone that covers a distance of some 100 Km, parallel to the Central American Basin or Entrenchment, and was felt from Costa Rica to Mexico. The rupture covered an area of approximately 6000 Km2.
A month later, on February 13 at 8:22 a.m., a second earthquake struck with a magnitude of 6.6 on the Richter Scale, located in San Pedro Nonualco, 30 Km southeast of San Salvador, at a depth of 6 Km. The tremors were felt in Guatemala and Honduras. Analysis of the origins of the earthquake indicate that it was associated with a local, geological fault that has a steep, vertical inclination, and was caused by displacement in the north-south or east-west direction. This earthquake was superficial and is associated with the central volcanic chain of El Salvador, a different seismic source than the one that produced the previous earthquake.
Central America is subject to a series of global geotectonic failures at the global level and is also exposed to local faultages in all the countries comprising it (Figure 2). To the north in the Atlantic, the North American and Caribbean Plates are interacting, divided by the Pit of Grand Cayman; to the south in the Pacific, the Cocos Plate can be found along all Central American countries (subduction zone), forming the Pit of Mesoamerica. This geological structure reaches the Cocos ridge at the border between Costa Rica and Panama. The plate of Nazca is active from Panama through the Galapagos Plate, with parallel movement to the Block of Panama that also affects Costa Rica through a transcurrent fault. This tectonic structure generates important seismic activity and has created major, destructive tremors in the Central American region. In the last hundred years, El Salvador has been affected by at least 13 major earthquakes. Among the most destructive were those of Jucuapa-Chinameca on May 6, 1951; San Salvador on May 3, 1965 and San Salvador on October 10, 1986.
It is important to note that the damages caused by previous earthquakes pale in comparison to the damages caused by these recent ones. Landslides have exacerbated the direct damages of the earthquakes and caused greater destruction. In El Salvador, the National Emergency Committee, (COEN from its Spanish name, Comité de Emergencia Nacional) is the agency that coordinates emergency activities. COEN is composed of the Ministries of National Defense, the Interior, Public Safety and Public Works, Agriculture and Livestock, Foreign Affairs, Education and Health, as well as relief, scientific, autonomous, and international Agencies, and private companies. This committee began to meet a day after the earthquake and provided the first data on the magnitude and severity of its effects on the population. These data were updated daily.
The data provided by COEN, until February 21 of this year, recorded 944 dead; 5,565 injured and a total of 1,364,160 victims. This represents a mortality rate for the country of 15.04 per 100,000 population. However, some departments were more seriously affected than others. The department of La Libertad, for example, recorded a higher mortality rate of 100.43 per 100,000 population. It is estimated that 21.74% of the entire population of the country was affected. The populations of Usulután and La Paz account for a disproportional amount of this percentage as these populations were affected almost 100% and 79%, respectively.
With regards to the affected structures, a total of 1,155 public buildings were damaged, while 169,792 houses were damaged, 108,261 destroyed and 688 buried. Additionally, 405 churches and 43 piers were damaged, amounting to a total of 280,344 affected constructions. Among the affected constructions, 38.6% corresponded to destroyed houses. The departments with the greatest proportion of houses destroyed among all buildings were La Libertad (50.6%), Usulután (48.5%), and Cuscatlán (47.1%).
With regard to health services, even though none of the health buildings were totally destroyed, of the total established health services infrastructure, 19 (63%) hospitals, 75 (21%) health units, and 12 (7%) health centers were damaged.
The water supply network was severely affected, particularly storage tanks in the pumping plants of the water supply system for some sectors of San Salvador and the general infrastructure in the Central, Western and Eastern regions. The costs of reported damages amount to more than five million dollars.
People who were evacuated from danger zones were re-located into 82 shelters, distributed in 10 of the most affected departments. A total of 64,606 people were taken to these shelters. The department of La Libertad contained the greatest registered number of shelters (18) and sheltered people (31,397).
An epidemiological surveillance system was activated by the country’s health authorities, given the epidemiological characteristics of the country at the time of the earthquake. Principal conditions included: 1) the recent dengue epidemic, 2) the presence of an epidemic of diarrheal disease by rotavirus, 3) the sporadic circulation of Vibrio cholera, 4) the presence of malaria endemic areas, 5) previous presence of cases of leptospirosis and 6) the presence of a cold front that affected the country after the disaster. Post-disaster sanitary conditions together with the epidemiological characteristics of the country favor the presence and dissemination of these illnesses, requiring improved surveillance. To achieve better monitoring and control of diseases after the disaster, all suspected cases of 20 diseases are reported to this surveillance system.
Until February 16 of this year, the principal health problems of the country were: acute respiratory infections with 117,871 cases (incidence rate of 1,878.2 per 100,000 population), diarrheal diseases and gastroenteritis with 29,128 cases (464.1), dermatoses with 8,620 cases (137.4), injuries with 7,901 cases (125.9) and depression and anxiety disorders with 7,252 cases (115.6). In the same period of time, 515,250 medical consultations had been carried out.
The second earthquake, of a smaller magnitude (6.6 degrees in the Richter Scale), occurred on February 13, and aggravated the health situation. By February 21, the COEN reported 315 deaths, 3,399 injuries, and 252,622 victims in all. The mortality rate for the country was of 5.0 per 100,000 population. The affected area includes the departments of Cuscatlán, La Paz, and San Vicente, which reported mortality rates of 81.3, 19.8, and 54.0 per 100,000 population, respectively.
With regard to structures, by February 21, 57,375 affected constructions had been recorded, of which 41,362 (72.1%) were totally destroyed. The greatest number of affected constructions was in the department of La Paz with 88.7%, followed by the departments of San Vicente and Cuscatlán, with 66.9% and 62.3% respectively.
On the occasions of both earthquakes, the Pan American Health Organization responded immediately, mobilizing both national and international financial and technical resources. The different areas of technical cooperation provided included disaster relief, assessment of the vulnerability of structures, hospital evaluation, use of the humanitarian supplies system (FUNDESUMA/SUMA), assistance with issues of mental and environmental health, information dissemination, and analysis of information and social communication.
Immediately after the first earthquake, the international community was present in the country to provide its collective assistance financially and in terms of human resources and materials. With these resources, the community supported activities that were carried out to assist the Salvadorian population. These efforts were undertaken by rescue personnel, physicians, nurses, paramedics and brigadiers from many countries. Additionally, personnel from Non-governmental Organizations (NGOs), supported activities to control the sanitary situation in the country. By the end of the month of February, the total monetary amount received for the two earthquakes is US$ 11,611,598. These funds have come from governments, international organizations, civil society, non-governmental organizations, banks, and private companies.
References:
(1) PAHO. Representation in El Salvador. Terremoto en El Salvador. Available
at: http://www.ops.org.sv/terremoto/
(2) Comité de Emergencia Nacional. Ministerio del Interior, El Salvador. Available
at: http://www.coen.gob.sv/
(3) Centro de Coordinación para la Prevención de los Desastres Naturales en
América Central. Sismicidad en Centroamérica. Available at: http://www.cepredenac.org/temas/sismo/
(4) Universidad de Chile. Departamente de Geofísica. Available at: http://www.dgf.uchile.cl/
(5) Departamento de Investigaciones Sismológicas. Centro de Investigaciones
Geotécnicas. Ministerio de Obras Públicas de El Salvador. Cronología de sismos
destructivos en El Salvador. Available at: http://www.geotecnico.com/sismologia/1crono.htm
(6) Incorporated Research Institutions for Seismology. Available at: http://www.iris.washington.edu/
Source: prepared by Dr. Gabriela Fernández and Dr. Guadalupe Verdejo, from PAHO's Special Program for Health Analysis (SHA), and Dr. Luis Jorge Pérez from PAHO's Emergency Preparedness and Disaster Relief Program (PED)
For more information, please visit PAHO's disasters page.
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Epidemiological Bulletin , Vol.
22 No. 1, March 2001