USGS Writes New Seismic Hazards, Risks and Design Report for South America

South America is one of the most earthquake-prone regions in the world and has seen huge losses throughout its history. A recently released USGS report provides probabilistic tools to help engineers assess seismic hazards, risks, and building code requirements, which can potentially save lives and money.

Over the past century, earthquakes have caused billions of dollars in damage and tens of thousands of casualties across the north and west of the South American continent. Seismic activity on this continent is driven by the South American Subduction Zone and other complex fault interactions. Future human and financial losses can be mitigated by making informed decisions based on where future earthquakes may occur, how often they might occur, and the strength of the ground that will shake. This information is the purpose of probabilistic (i.e. based on mathematical prediction) models of seismic risks that are applied in building codes, insurance models and public policies.

Destructive faults and earthquakes over the past century along the South American Subduction Zone (public domain)

New data opens up new opportunities

Over the past two decades, the USGS has worked with South American colleagues to develop models and maps to support national contingency planning efforts. Although there are a number of national studies that have assessed the hazards and risks associated with earthquakes, coverage is hardly uniform or comprehensive on the South American continent. This report is the first to apply standardized methodologies and tools for hazard and risk assessments, to reduce gaps at national borders and identify areas of high hazard and risk in each country. The study draws on five important data sets and methodologies: (1) an updated USGS earthquake catalog (ComCat), (2) known and mapped fault models generated by the USGS over the past 30 years in collaboration with South American scientists, (3) the latest seismic ground motion models applied in maps of USGS hazards, (4) USGS PAGER vulnerability models (“PAGER” stands for Prompt Assessment of Global Earthquakes for Response, and it is a system that provides estimates of the impact on deaths and economic losses from major earthquakes in the world), and (5) methods applied in US building codes. This information can be used to identify high risk areas and develop strategies to reinforce vulnerable buildings.

The new results indicate that more than 160 million people (or about a third of the total population of South America) live in areas with significantly high seismic risk, mainly in the northern and western parts of the continent where earthquakes of earth associated with subduction and crustal faults occur. The most common. Figures 2-3 indicate that the risk is not uniform or limited to coastal areas only. Countries like Venezuela, Colombia, Ecuador and Peru face high dangers and risks; Chile also faces a high risk, but the vulnerability of buildings is much lower compared to countries in the north due to modern and strict building codes.

Comparative maps of South America showing 100-year earthquake projections.

Maps of South America showing 100-year earthquake projections. (Public domain)

A cornerstone of international collaboration

About a decade ago, South American scientists at the Centro Regional Seismological para América del Sur asked USGS scientists to collaborate on the development of hazard, risk and earthquake design maps for South America. Over the past decade, several workshops and discussions with South American colleagues have been held to discuss the input data and assess the assessments. In June 2016, the USGS and the University of Chile jointly organized a seismic risk planning workshop in Costa Rica in which 24 scientists from 17 Latin American countries participated. This effort was funded by the United States Agency for International Development’s Overseas Disaster Assistance Program, which is dedicated to mitigating risk in the region. The report describing the results was recently published in the journal “Bulletin of the Seismological Society of America”.

Start with science

The USGS provides essential scientific data for understanding earthquake risk, because communities cannot plan for earthquakes if they do not know the predicted occurrence of the earthquake and potential tremors. These USGS models reflect the best and most current understanding of seismic science and engineering.

Earthquakes are a global concern; In the past decade alone, earthquake events have claimed tens of thousands of lives and caused hundreds of billions of dollars in economic impact. These international collaborations are an important part of ensuring that everyone can benefit from the best science available. For example, USGS scientists use the scientific expertise and experience they gain from working with collaborators in South America and apply it to similar situations here in the United States. In return, scientists in other countries can benefit from the lessons learned by USGS scientists responding to national earthquakes.

In the United States, the risk of an earthquake continues to grow with increased exposure of the population and development in areas of the country at risk. Understanding earthquake risks is essential for informed policies, priorities, strategies and funding decisions to protect communities most at risk.

The datasets and models presented in this study and the results are publicly available here.

Learn more

The USGS provides early alerts of the potential impacts of an earthquake through its Rapid assessment of global earthquakes for response system.

Sign up to receive earthquake notifications via the USGS Earthquake Notification System.

If you feel an earthquake, report your experience to the USGS »Did you feel it?” website.

Learn how to prepare at home using the 7 steps to seismic safety of the guide “Take root in the earthquake country», Written for different regions of the country and in several languages.

More information on what you can do to prepare for earthquakes at work and at home is available on the Great ShakeOut site.

About Florence L. Silvia

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