Assessing global earthquake risks: the Global Earthquake Model (GEM) initiative - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 828

The software that will power the calculations for the regional and global
hazard and risk products of GEM (OpenQuake Engine) was openly
released in January 2011 through an open source development platform
(GitHub) (http://openquake.org). An Agile framework 2 is applied to the
development of the OpenQuake Engine software as this caters for the
tuning of requirements and priorities as they evolve.
For the hazard calculations, the software will allow users to obtain the
following outputs (illustrated in Fig. 30.8) through classical PSHA or
through a stochastic event-based approach:

• hazard curves and hazards maps (for different probabilities of exceed-

ance within a given time span); the mean, a given fractile, or for each
branch of the logic tree;

• stochastic event sets and associated ground-motion fi elds;

• disaggregation plots in terms of different combinations of magnitude,

distance, epsilon, tectonic region type;

• uniform hazard spectra.

For the physical risk calculations, OpenQuake Engine will allow users to
obtain the following results, through a number of different methodologies:

• loss exceedance curves (loss versus probability of exceedance in a given
time span, both for single assets and portfolios of assets);
• conditional loss maps describing the geographical distribution of values
of loss with a fi xed probability of exceedance in a given time span;
• mean loss maps describing the geographic distribution of mean loss
within a given time span;

• damage maps describing the geographical distribution of mean number/

area/percentage of damage at a given limit state for a given determin-
istic event;

• loss statistics per event or across all events (mean loss, standard devia-

tion of loss, etc.).

The OpenQuake Engine is hence key to sophisticated calculations. Users
will be able to access and interact with the global datasets and models
through the OpenQuake platform. Use of the platform in for-profi t contexts
will have a fair cost, to facilitate academic and basic use worldwide. Reports
and manuals with background to the science and tools will also be available,
and spaces where users can share, discuss and help improve them. There
will be several suites of the OpenQuake platform, attuned to the needs of
the various groups GEM aims to serve.

2 Agile software development is a group of software development methods based on iterative
and incremental development, where requirements and solutions evolve through collaboration
between self-organising, cross-functional teams.