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 and how priorities are set for mitigation and resilience planning.

This documentation describes the GEM Global 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 structural systems and seismic design-code levels

  2. Improved numerical modelling: Efficient multi-degree-of-freedom (MDOF) stick-and-mass models to simulate seismic response at scale

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

  4. New fragility and vulnerability functions: Tailored specifically to structural damage with explicit treatment of storey-level demands

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/LFM+CDH+ERH/H:3/RES identifies a three-storey (H:3) reinforced concrete (CR) moment-resisting frame (LFM) with high code design (CDH), high earthquake-resistant design (ERH), and residential (RES) occupancy.

Building Attributes

Attribute

String

Details

Construction Material

CR

Reinforced concrete

EU

Earth construction

INF

Informal construction

MCF

Confined masonry

MR

Reinforced masonry

MUR

Unreinforced masonry

MUR+ADO

Adobe construction

MUR+CBH

Concrete block

MUR+CLBRH

Hollow clay brick

MUR+CLBRS

Solid clay brick

MUR+STDRE

Dressed stone

MUR+STRUB

Rubble stone

S

Steel

S+MCF

Steel and confined masonry

SRC

Concrete composite with steel sections

W

Timber

W+WBB

Bamboo

W+WWD

Wattle and daub

Lateral Load-Resisting System

LDUAL

Dual system

LFINF

Infilled frame

LFM

Moment frame

LPB

Post and beam

LWAL

Wall system

LFBR

Braced frame

Code Level

CDN

Pre-code

CDL

Low code

CDM

Moderate code

CDH

High code

Earthquake-Resistant Design

ERN

No Earthquake-Resistant Design

ERL

Low

ERM

Moderate

ERH

High

ERS

Special

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: Stick-and-mass MDOF systems for over 1,000 building classes

  2. Nonlinear Analysis: Cloud-based nonlinear time-history analysis (NLTHA) using an extensive suite of ground motions

  3. Fragility Derivation: Fragility functions characterising structural damage conditional on ground-shaking intensity measures

  4. Vulnerability Assembly: Comprehensive vulnerability functions combining fragility with damage-to-loss ratios

Data Access

All derived functions are released in an open-access repository:

References

  • Aljawhari K., Nafeh A.M.B., Silva V. (2025). A New Global Vulnerability Model for Regional Seismic Risk Assessments: Part 1 – Structural Vulnerability.

  • Martins L., Silva V. (2021). Development of a fragility and vulnerability model for global seismic risk analyses. Bulletin of Earthquake Engineering.

  • Silva V. et al. (2022). A Building Classification System for Multi-hazard Risk Assessment. International Journal of Disaster Risk Science.