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Seismic Hazard Assessment

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.

Current state-of-the-art Probabilistic Seismic Hazard Input models must include to the largest extent possible fault sources. The creation of a fault-based PSHA input model requires integration of existing fault data into a unified framework.

In much of the world, as well as in South America, seismicity is distributed over regions where active/hazardous faults have been already identified, but the current information related to these tectonic structures or the format used for its compilation is not suitable for the PSHA modeling. The goal of this topic is the collection and harmonization of available information related to crustal neotectonic structures in continental South America, which are or could be considered as potential seismogenic sources. The starting point will be the existing set of inventories on Quaternary deformation in the region and in particular: the “World Map of major active faults project - ILP-II2” and the “Multinational Andean project - PMA”. The information in these databases will be updated and upgraded through a collaborative effort (i.e. South American Neotectonic Group – SNG), among specialists and working groups in the region. The SNG efforts will involve specialists and neotectonic data from Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Uruguay and Venezuela. The information will be compiled and uploaded through an uniform criteria for data inventory and cartography, which should be agreed among participants in the beginning and following the standards and procedures proposed by GEM with these purposes.

The resulting database will constitute a free-access dataset, available on Internet.

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 11:47
  • by Marco Pagani