Overview

Introduction

Earthquakes remain among the most damaging natural hazards, with more than one million deaths and nearly a trillion USD in economic losses recorded over the past century. A substantial share of these impacts stems from inadequate performance of buildings not designed to satisfy seismic provisions. This reality makes reliable vulnerability functions essential for producing meaningful loss estimates in seismic risk assessments, thereby shaping how risk drivers are identified.

This documentation describes the GEM Global Seismic Vulnerability Model, a comprehensive database of fragility and vulnerability functions developed by the Global Earthquake Model (GEM) Foundation for seismic risk assessment. The model advances large-scale seismic risk modelling through four key pillars:

  1. Expanded building class coverage: Over 1,000 building classes capturing a wide range of primary vulnerability modifiers such as: primary construction material, lateral load-resisting system, seismic design code and earthquake-resistant design levels and number of storeys

  2. Improved numerical modelling: Efficient multi-degree-of-freedom (MDOF) stick-and-mass models to simulate seismic response at scale for explicit treatment of storey- and floor-level demands

  3. Extensive ground-motion records: A comprehensive suite spanning diverse tectonic environments (active shallow crust, stable continental, and subduction zones)

  4. New damage and loss models: Fragility functions describing the probability of exceeding pre-defined damage states (DSs) and vulnerability functions characterising the expected loss - economic and human-centric - both conditioned on a ground-shaking intensity measure (IM) with explicit treatment of uncertainty

Building Classification

Buildings are categorised based on primary construction materials, lateral load-resisting systems, seismic design code, earthquake-resistant design levels, and height. Each building class is encoded using a unique taxonomy string following GEM’s taxonomy system.

For instance, CR/LFINF/CDL+ERL/H:3/RES identifies a three-storey (H:3) reinforced concrete (CR) infilled moment-resisting frame (LFINF) with low code design (CDL), low earthquake-resistant design (ERL), and residential (RES) occupancy.

Building Attributes

Attribute

String

Details

Construction Material

CR

Reinforced Concrete

E

Earth Construction

ME+MEO

Metal Sheet Construction (Informal)

MCF

Confined Masonry

MR

Reinforced Masonry

MUR

Unreinforced Masonry

MUR+ADO

Adobe Construction

MUR+CBH

Unreinforced Masonry + Concrete Block

MUR+CLBRH

Unreinforced Masonry + Hollow Clay Brick

MUR+CLBRS

Unreinforced Masonry+ Solid Clay Brick

MUR+STDRE

Unreinforced Masonry + Dressed Stone

MUR+STRUB

Unreinforced Masonry + Rubble Stone

S

Steel

SRC

Concrete Composite with Steel Sections

W

Unknown Timber

W+WHE

Heavy or Mass Timber

W+WLI

Light Timber

W+WBB

Bamboo

W+WWD

Wattle and daub

Lateral Load-Resisting System

LDUAL

Dual System

LFINF

Infilled Moment-Resisting Frame

LFM

Bare Moment Frame

LPB

Post and Beam/ Large Panel Building

LWAL

Load-Bearing Wall/ Shear Wall System

LFBR

Braced Frame

Code Level

CDN

No Code

CDL

Low Code

CDM

Moderate Code

CDH

High Code

CDS

Severe Code

Earthquake-Resistant Design

ERN

No Earthquake-Resistant Design

ERL

Low Earthquake-Resistant Design

ERM

Moderate Earthquake-Resistant Design

ERH

High Earthquake-Resistant Design

ERS

Severe Earthquake-Resistant Design

Height

H:n

n is the number of storeys

Methodology Overview

The methodology adopted to develop the global vulnerability database consists of:

  1. Numerical Modelling of Idealised System: Calibration and modelling of stick-and-mass MDOF systems for over 1,000 building classes

  2. Nonlinear Time-History Analysis: Modified cloud analysis (MCA)-based nonlinear time-history analysis using an extensive suite of unscaled ground motions (or with limited scaling)

  3. Fragility Derivation: Fragility function fitting using probabilistic seismic demand modelling following MCA, characterising structural damage conditional on ground-shaking IMs

  4. Vulnerability Function Assembly: Comprehensive vulnerability functions combining fragility with damage-to-loss ratios and integrating seismic demands (i.e., peak storey drifts and peak floor acceleration) with storey loss functions derived from component-based analysis

How Were the Models Developed?

A complete description of the vulnerability modelling workflow is available in the following sections of the model documentation. The models were developed using the OpenQuake Vulnerability Modeller’s Toolkit OQ-VMTK (Nafeh et al., 2026), a suite of open-access tools created by the vulnerability modellers at the GEM Foundation to provide earthquake engineers with a comprehensive platform for developing fragility and vulnerability models. A demonstration of the capabilities and functionalities of the VMTK is also provided in the OQ-VMTK ‘demos’ folder. A documentation of the OQ-VMTK modules and functionalities is available on: https://gemsciencetools.github.io/oq-vmtk/

References

Please cite this work as follows:

  • Nafeh, A.M.B., Aljawhari, K. & Silva, V. (2025), The 2025 Global Vulnerability Model of the GEM Foundation, GitHub. https://github.com/gem/global_vulnerability_model

  • Aljawhari, K., Nafeh, A.M.B. & Silva, V. A new global vulnerability model for regional seismic risk assessments: Part 1 – structural vulnerability. Bull Earthquake Eng (2026). https://doi.org/10.1007/s10518-026-02443-7

  • Nafeh, A.M.B., Aljawhari, K., & Silva, V. A new global vulnerability model for regional seismic risk assessments: Part 2 – nonstructural and building contents vulnerability. In Press