Resumo

ORDAZ HERNANDEZ, Alexis. Socioeconomic Possible Impact for a Moderate Magnitude Seism. Application to San Cristóbal City, Western Cuba. Invest. Geog [online]. 2020, n.102, e59839.  Epub 09-Mar-2021. ISSN 2448-7279.  https://doi.org/10.14350/rig.59839.

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.

Palavras-chave : Seism; hazard; structural vulnerability; socioeconomic losts.