Glossary of Terms#


An asset is something of value, which can include buildings and population. For example, an asset can include an individual building at a given location, or a number of buildings that are grouped and co-located at a single location and are classified with the same taxonomy.


The simplest element in a logic tree; it belongs to a branch set where it represents one possible option among a finite number of alternatives. A branch is associated with a weight value (Scherbaum and Kuehn, 2011) if the branch set represents the epistemic uncertainty on a parameter or a model when the branch set is used to specify alternative models (e.g. district Magnitude-Frequency Distributions(MFDs)).

branch set#

The structure describing the epistemic uncertainty on a specific parameter or model included in a logic tree structure. It ensembles a number of branches, each one representing a discrete alternative.

consequence function#

Consequence functions describe the probability distribution of loss, given a performance level and are generally derived empirically.


A parameter used in the calculation of insured losses that establishes the economic value that needs to be deducted from the ground-up losses

earthquake rupture#

A 3D surface - representing a portion or the entire fault surface - over which a slip event (i.e. an earthquake) occurs.

event loss table#

A list of ruptures from a number of stochastic event sets and respective aggregated losses.

exposure model#

A set of assets grouped according to their geographical location, taxonomy and value.

fragility function#

the probability of exceeding a set of limit states, given an intensity measure level. These functions can be discrete or continuous.

fragility model#

A set of fragility functions used to model the fragility of all the assets in the exposure model.

ground-motion field#

An object describing the geographic distribution around a rupture of a ground motion intensity measure.

ground-motion prediction equation#

An equation that - given some fundamental parameters characterizing the source, the propagation path and the site (in the simplest case magnitude, distance and VS,30) - computes the value GM of a (scalar) ground motion intensity parameter.

ground-up losses#

Total direct losses from a collection of assets due to a seismic event.

insured losses#

Fraction of the ground-up losses that can be covered by the insurance industry, ac- cording to a certain policy which defines limits and deductibles.


A parameter used in the calculation of insured losses that establishes the maximum economic amount that can be covered by the insurance industry, according to a certain insurance policy.

loss disaggregation#

A methodology to investigate what are the characteristics of the seismic events that are contributing more significantly to the losses at a given location, in terms of fundamental variables commonly used to characterize seismic sources (e.g. magnitude, source-site distance, location).

seismic source data#

An object containing the information necessary to completely describe a PSHA seismic source i.e. seismic source type, position, geometry and seismicity occurrence model.

seismic source model#

An object containing a list of seismic source data.

stochastic event set#

An object containing one or many seismicity histories.


Scheme used to classify the assets. For buildings, a classification scheme has been proposed by GEM which considers a number of attributes including lateral load resisting system and its material, height, year of construction. The taxonomy is currently used to link the assets in the exposure model to the relevant vulnerability function or fragility function.

vulnerability function#

A function that describes the probability distribution of loss ratio, conditioned on an intensity measure level. Currently only discrete vulnerability functions are supported.

vulnerability model#

A set of vulnerability functions used to model the physical vulnerability of all the assets in the exposure model.