The GEM database of seismic hazard models

Damiano Monelli1, Marco Pagani1, Graeme Weatherill1,

Julio Garcia1

1GEM Hazard Team - GEM Foundation, Pavia, Italy

Second European Conference on Earthquake Engineering and Seismology –Istanbul 24 - 29 August, 2014

Seismic hazard information around the world

• A number of seismic hazard models are nowadays available for various regions in the world as produced by different geological surveys or scientific consortia

Seismic hazard information around the world

• Models are developed following different approaches (reflecting different tectonic regions and data availability)

• Models are defined following different data formats

• Software used for the implementation is sometime not-available or is proprietary

• When the software is available, issues such as lack of documentation, support and maintenance may prevent, in practice, any attempt to reproduce model results

Hazard models are difficult to reproduce (and hence to inspect) and to compare

The GEM Seismic Hazard Models Database

• By working together with Geological Surveys and Scientific Consortia in different regions of the World, GEM is assembling a database of seismic hazard models relying on two main pillars:

– Common data model based on NRML (‘Natural hazards’ Risk Markup Language’) schema: https://github.com/gem/oq-nrmllib

– Open calculation software: OpenQuake, https://github.com/gem/oq-engine

• The usage of a common data model allows to abstract an hazard model from a particular software implementation (i.e. making a model software-independent) and allows for an easier model comparison

• The usage of an open-software is fundamental to guarantee reproducibility and transparency

The (current) GEM DB of Seismic Hazard Models

EuropeSHARE - 2013

South East Asia USGS - 2007

AustraliaGA - 2012

South AmericaUSGS - 2010

Central AmericaRESIS II - 2010

Caribbean – Lesser AntillesGeoter - 2002

USAUSGS - 2008

AlaskaUSGS - 2007

CanadaGSC - 2005

Color (from blue to purple) proportional to total occurrence rate

The GEM DB of Seismic Hazard Model: QA tests

• Apart from the SHARE model (since the beginning developed using OpenQuake), all models have been translated from the original format to the Natural hazard’ Risk Markup Language (NRML) format

• Quality assurance tests are needed to verify that models stored in the DB provide results in agreement with the results computed by the original modelers

QA tests: USA 2008

QA tests: USA 2008

OpenQuake missing‘New Madrid Cluster model’

Missing epistemic uncertaintiesin median ground motion for‘Active Shallow Crust’ GMPEs.Other reasons ??

QA tests: USA 2008

QA tests: USA 2008

QA tests: Canada 2005

QA tests: Canada 2005

Largest differences along the Queen Charlotte Fault

QA tests: Australia 2012

QA tests: Australia 2012

• The 2012 Australia Model

QA tests reveal discrepancies due to different modeling approaches

Hazard Curves computed using a gridded seismicity model for California included in 2008 USA model

QA tests reveal discrepancies due to different modeling approaches

More details inMonelli et. al. 2014, BSSA

Conclusions

• The GEM DB of seismic hazard models offers a single framework to access in a uniform way seismic hazard information for different regions in the world

• Uniformity is guaranteed by the usage of a single open data model (NRML: https://github.com/gem/oq-nrmllib)

• Transparency is guaranteed by the usage of an open software (OpenQuake: http://www.globalquakemodel.org/openquake)

• Reproducibility is guaranteed, as much as possible, through the implementation of Quality Assurance tests

Conclusions

• Main benefits for the scientific and engineering communities:

– Being able to reproduce model results which are either impossible or difficult to reproduce using the original model implementation

– Models are open, they can be inspected and changed.

– Different models can be better compared because defined using the same data model and results are computed using the same software

Conclusions

• New data can be generated (models developed for engineering design can be used for instance to generate synthetic catalogs for risk assessment purposes)

Conclusions

• The GEM DB of seismic hazard models will be released in conjunction with the OpenQuake-Platform at the beginning of 2015

Except where otherwise noted, this work is licensed under: creativecommons.org/licenses/by-nc-nd/4.0/

Please attribute to the GEM Foundation with a link to - www.globalearthquakemodel.org