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Seismic Hazard Assessment

Seismic hazard modelling in South America presents scientists and engineers with a diverse set of challenges. Incorporating some of the most seismically active regions on the planet, and including many of the largest earthquakes ever recorded, the South American subduction zone dominantes the earthquake hazard in the west of the continent and provides the principal tectonic force driving the shallow non-subduction earthquakes in western Argentina, Bolivia, Ecuador, Peru and Colombia. In addition to the tectonic complexity, further challenges arise due to the current state of knowledge, with inhomogeneous characterisation of seismicity, active faulting and strong motions between different countries.

It is within this context that the seismic hazard component SARA established several key goals for improving the state of regional seismic hazard assessment in South America. These include the harmonisation of critical earthquake data sets (including both historical and instrumental earthquake catalogues, seismically active faults, and local and national databases strong motion recordings), the development of data common standards for representation, and the development open tools for both data collection and interpretation. Whilst the technical developments of the SARA hazard component are both necessary and valuable, it is the active engagement of scientists and engineers from within the region that may best ensure that the project’s outcomes will continue to impact upon seismic hazard assessment after completion of the project. The SARA hazard component was organised into seven research areas, with scientific experts from different institutions across the region participating, and often leading, the activities in the different topics, in response to a call for proposals published by GEM in 2013. The hazard work package was organised into 7 research topics. Below we provide the definition of each topic:

Topic 1: Current status

Define the current state-of-the-art of seismic hazard in the region by collecting available PSHA models and porting them into OpenQuake engine format.

Building a new seismic hazard model does not mean overlooking the past, previous and currently under-development models should be considered in the creation of a new regional model to ensure consistent and continuous improvement of models used to compute a probabilistic seismic hazard assessment (PSHA) study. In this context, the primary task to be achieved by the hazard component was to appraise the current state-of-the-art in (PSHA) in the South American region.

Topic 2: Active faults

Build a harmonized database of shallow active faults.

Topic 2

Topic 3: Subduction

Creating a PSHA seismicity occurrence model for the subduction structures along the western coast of South America.

The areas along the west coast of South America where the Nazca Plate subducts beneath the South American Plate, with a rate of 7/8 cm/yr, are exposed to high level of seismic risk. This process is capable of generating a M>= 8 earthquake roughly every decade and a M>9 earthquake every century (DeMets et al., 1980; Norabuena et al., 1999). Several interpretations of the subduction process for South America have been proposed in the recent scientific literature, but from a hazard perspective, little of this information was incorporated into seismic source modes at present.

This topic therefore is focusing on the collection of information useful for the characterization of the subduction process along the western coast of South America and the creation of a uniform model to be used in PSHA analysis. The task will be focused on defining the subduction geometry and its segmentation starting from recently developed global models of subduction geometry such as SLAB 1.0 (Hayes and Wald, 2009; Hayes et al., 2012), parametric investigations by Heuret et al. (2011) and subduction segments included in national PSHA models. The primary outcome of this task will be to define a model of the subduction interface with the aim of ensuring consistency with the OpenQuake-engine complex fault typology, which is designed for application in subduction environments.

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  • Last modified: 2015/12/29 11:49
  • by Marco Pagani