Posible impacto socioeconómico por sismo de moderada magnitud. Aplicación a la ciudad de San Cristóbal, Cuba occidental

• Autores: Alexis Ordaz Hernández
• Localización: Investigaciones geográficas, ISSN 0188-4611, ISSN-e 2448-7279, Nº. 102, 2020
• Idioma: español
• Títulos paralelos:
  • Socioeconomic Possible Impact for a Moderate Magnitude Seism. Application to San Cristóbal City, Western Cuba
• Enlaces
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• Resumen
  • español

    El artículo aborda las pérdidas socioeconómicas esperadas por un sismo de moderada magnitud para la ciudad de San Cristóbal en el occidente de Cuba. Esta localidad experimentó un sismo con magnitud estimada de 6.0 grados Richter e intensidad VIII grados MSK el 23 de enero de 1880, el cual destruyó gran parte de la infraestructura de la época. En el trabajo se definen de manera precisa los niveles de peligrosidad sísmica en función de las características geológicas locales para los periodos de retornos (T) de 100 y 475 años. Posteriormente, se estiman los niveles de daños a la infraestructura residencial empleando información catastral y las matrices de probabilidad de daños diseñadas por el Centro Nacional de Investigaciones Sismológicas de Cuba (Cenais).Para las condiciones actuales de vulnerabilidad estructural y los niveles de peligrosidad sísmica estimados, se pronostica que 5 680 viviendas sufrirán algún tipo de daño, esto en caso de que ocurriera un sismo similar al del 23 de enero de 1880. De igual forma, en función de la distribución de los habitantes en el espacio urbano, se pronostica que 67 personas queden sin hogar, 59 resulten heridas y una fallezca. La metodología empleada sirve de modelo para otros sitios en el entorno geográfico del Caribe que carezcan de evaluaciones básicas de estimaciones de daños frente a terremotos.

  • English

    Contemporary history consistently confirms that earthquakes are a natural phenomenon of significant social impact. In reality, seismic episodes, especially in urban settings, trigger a series of alterations in everyday life that are extremely difficult to predict. This reality is far more severe in developing countries, characterized by financial structures that fall short to respond to major natural disasters.In the Caribbean region, studies to estimate socioeconomic losses resulting from the effects of natural phenomena are scrace, especially as related to earthquakes. This limitation restrains the proposals for risk mitigation plans for potential risk scenarios.This investigation examines the foreseen socioeconomic losses associated with a moderate-intensity earthquake affecting San Cristóbal City, western Cuba. On 23 January 1880, this town was affected by an earthquake of magnitude 6.0 Richter Scale and intensity of VIII degrees MSK, the 23 January 1880, which destroyed a large portion of the infrastructure of the time.  The study area has been at the core of several investigations in the 21st century; particularly, works have addressed geotechnical and tectonic aspects. Its history is sufficient to evolve to issues directly linked to local risk management, especially to estimate the socioeconomic impact under a hypothetic seismic scenario similar to the one experienced in 1880.The methodology used allows a simple quantitative expression of potential socioeconomic damage in an urban scenario facing moderate-intensity earthquakes, and uses the "urban block" as the basic information unit. This study assumes the unified definitions put forward in the meeting on Natural Disasters and Vulnerability Analysis held in 1979 as theoretical framework. The methodological bases set in this meeting laid the general guidelines and basic elements to consider in order to estimate the potential human losses and effects on economic activities, should a disaster occur. More recent works have reinforced the methodology, including aspects such as resilience, scientific and technological capacity of communities, and exposure time, among other elements.This work precisely defines seismic hazard levels according to local geological characteristics for return (T) periods of 100 and 475 years. Subsequently, household infrastructure damage levels are estimated using cadastral information and damage probability matrices elaborted by the National Center for Seismic Research of Cuba.This research focuses exclusively on the analysis of the household sector. The map of structural vulnerability contains a comprehensive database of essential attributes, such as type of structure, technical condition, number of inhabitants per type of structure, area occupied by each structure, and number of levels, among others. At the same time, it does not ignore the existence of other elements exposed, which can be perfectly considered for future research, including presence of public buildings (hospitals and schools), and even other public structures such as bridges.According to the current conditions of structural vulnerability and the estimated seismic hazard levels, 5,680 homes are expected to be damaged to some extent should  an earthquake similar to the one in 23 January 1880 occur. Likewise, and depending on the distribution of inhabitants in the urban space, 67 people are expected to become homeless, 59 may be hurt, and one person may die.Finally, the results obtained are considered to be consistent with the urban scenario studied and given the seismic hazard level in the Caribbean region, with the products obtained being a significant contribution for the local management of seismic risk.  Also, we consider that the methodology used serves as a model for other locations in the Caribbean area lacking basic estimates of potential damage for earthquake scenarios.