Illustrative: plants and ports, the routes between them and goods moving along; one node is disrupted and its routes stall

Risk Academy, led by the Nexus Consortium · Course catalogue · Systems and Nexus Studies

Systemic Risk and Complexity

Supply network and economic contagion

Supply network and economic contagion, taught twice over: as the working methods of the field and as its frontier since 2024, with labs on the Academy's tools, open data and the Nexus Standards.

Core course Frontier course

The discipline

01Core course · L2 Intermediate

Supply network and economic contagion: foundations and practice

This area covers how shocks propagate through production networks, trade and finance: input-output linkages, supplier concentration, inventories and the network structure that turns a local disruption into a global one.

Level
L2 Intermediate
Study time
about 24 hours (planning estimate)
Status
Planned
Prerequisites
An L1 course in the area, or an entry review

Why now

Red Sea diversions from late 2023 and the 2024 Baltimore bridge collapse showed shocks spreading through shipping and firm networks; IMF PortWatch now tracks port and chokepoint activity daily from satellite AIS data. Nature Sustainability, Firm-level propagation of shocks through supply-chain networks (Inoue and Todo), 2019

Learning outcomes

  1. Define input-output model and the other key terms of the discipline and use them correctly in a written case
  2. Explain input-output models and the inoperability model and production network structure and concentration with a worked example and its source
  3. Apply the discipline's method to a documented case and explain each result with its source
  4. Analyse a named case against higher-tier supplier dependencies, stating evidence, date and limits

Modules

  1. Input-output models and the inoperability model
    • Input-output models and the inoperability model
    • Production network structure and concentration
    • Higher-tier supplier dependencies
  2. Inventories, buffers and bullwhip effects
    • Inventories, buffers and bullwhip effects
    • Agent-based models of supply chains
    • Network robustness, percolation and chokepoints
  3. Trade and financial contagion
    • Trade and financial contagion
    • Firm-level network data and its gaps
    • Disruption scenarios and stress tests
  4. Lab: the discipline's method
    • A supplier that stops delivering makes its customers inoperable in proportion to how much of their input it supplied; the loss multiplies through the input-output structure, and the days of inventory on hand decide whether the shock passes through or dies out before the supplier recovers.
    • Work the method through a documented case and explain each result
    • Read the method's sources and stated values

Labs with Academy tools

Open data

Assessment

  • 40%Lab recordWork the discipline's method through a documented case and explain each result with its source and date
  • 40%Case memoApply the discipline's methods to a named place or organisation, stating evidence and limits
  • 20%Key terms checkShort answers on the key terms, marked against the definitions

Delivery

  • Self-paced online, with the labs in the browser
  • Cohort study over six to eight weeks, with a weekly lab review
  • Co-delivered with a partner institution, inside its own courses

Partner on this course

  • Co-teach a module and bring a current case from your work
  • Host a cohort for your learners, with your own schedule and review
  • Contribute a lab: a dataset your institution publishes openly, or a model
  • Review the course content and its references before it opens
  • Translate the course and adapt its cases to your region

How institutions and experts take part

In the Academy LMS

Course on the learning platform
Intermediate, 4 topics
Cohort group
A community group for each cohort of learners
Achievement
Recorded on completion of the assessed work

References

  1. Haimes and Jiang, Leontief-based model of risk in complex interconnected infrastructures, 2001
  2. Hallegatte, An adaptive regional input-output model and its application to the assessment of the economic cost of Katrina, 2008
  3. Carvalho, Nirei, Saito and Tahbaz-Salehi, Supply chain disruptions: evidence from the Great East Japan earthquake, 2021
02Live map

Activity and hazards in Egypt and the Nile Delta

Night-time lights and population, the geography of production and markets, with floods and sea state, over Egypt and the Nile Delta.

The interactive map needs JavaScript; the layer list and sources are below.

Layers 2

Activity and hazards

Latest available

NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth

Loading the latest NASA imagery.

Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.

Activity and hazards, framed on Egypt and the Nile Delta.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.

Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONETSources and licences

  • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • Center for International Earth Science Information Network (CIESIN), Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Density, Revision 11. NASA Socioeconomic Data and Applications Center (SEDAC). Licensed under CC BY 4.0. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). doi:10.7927/H49C6VHW. CC BY 4.0
  • VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
  • Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
  • © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). ODbL
  • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
  • Globe: MapLibre GL JS 6.9.1, BSD-3-Clause, © MapLibre contributors.
  • Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
  • NASA GIBS: We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS).
  • Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
  • Optional layers (5 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.

Layers and dates

  • Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
  • Population density, 2020: Population: CIESIN, Columbia University, Gridded Population of the World v4.11 (2018), NASA SEDAC, CC BY 4.0 · static
  • Flood water, 3-day composite: VIIRS Global Flood Product, NASA LANCE · 14 Oct 2026
  • Sea surface temperature anomaly: GHRSST MUR25, NASA JPL PO.DAAC · 12 Oct 2026
  • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026

03How learning runs

How learning runs, as a process you can run

Select a scenario and press Play: course, pathway, practice, faculty, cells and record.

04What is changing

What is changing, with standards and evidence

Supply network and economic contagion: frontier methods

The methods, data, tools and studies that changed supply network and economic contagion between 2024 and 2026, taught by reproducing them on open data.

Level
L3 Advanced
Study time
about 28 hours (planning estimate)
Status
Planned
Prerequisites
Supply network and economic contagion: foundations and practice; Working knowledge of a scripting language (Python or R) for the labs

Why now

Red Sea diversions from late 2023 and the 2024 Baltimore bridge collapse showed shocks spreading through shipping and firm networks; IMF PortWatch now tracks port and chokepoint activity daily from satellite AIS data. Nature Sustainability, Firm-level propagation of shocks through supply-chain networks (Inoue and Todo), 2019

Learning outcomes

  1. Explain what changed in supply network and economic contagion since 2024 and cite the studies, data or rules behind each change
  2. Reproduce input-output propagation on open data and state the uncertainty of the result
  3. Evaluate a 2024 to 2026 study: its question, data, method, limits and what it changes for practice
  4. Design an analysis that combines a frontier method with the faculty's instruments, and justify each choice

Modules

  1. Input-output propagation
    • Leontief and Ghosh models
    • Multi-regional tables (OECD ICIO, EXIOBASE)
    • Limits of fixed coefficients
  2. Firm networks
    • Agent-based supply chain models
    • Firm-level systemic risk indices
    • Inventory and substitution
  3. Chokepoints
    • Maritime chokepoints and rerouting
    • Port disruption monitoring
    • Critical inputs and concentration
  4. Reproduction lab
    • Extend the discipline's method with one frontier method and compare its results
    • State the uncertainty and the limits of the result
    • Peer review against a shared checklist

Labs with Academy tools

Open data

Assessment

  • 50%Method reproductionReproduce one frontier method on open data and state the uncertainty of the result
  • 30%Study reviewA critical review of a 2024 to 2026 study: question, data, method, limits, what it changes
  • 20%Peer reviewReview two other learners' reproductions against a shared checklist

Delivery

  • Self-paced online, with the labs in the browser
  • Cohort study over six to eight weeks, with a weekly lab review
  • Co-delivered with a partner institution, inside its own courses

Partner on this course

  • Co-teach a module and bring a current case from your work
  • Host a cohort for your learners, with your own schedule and review
  • Contribute a lab: a dataset your institution publishes openly, or a model
  • Review the course content and its references before it opens
  • Translate the course and adapt its cases to your region

How institutions and experts take part

In the Academy LMS

Course on the learning platform
Expert, 4 topics
Cohort group
A community group for each cohort of learners
Achievement
Recorded on completion of the assessed work

References

  1. Nature Sustainability, Firm-level propagation of shocks through supply-chain networks (Inoue and Todo), 2019
  2. Scientific Reports, Quantifying firm-level economic systemic risk from nation-wide supply networks (Diem et al.), 2022
  3. UNCTAD, Review of Maritime Transport 2024, 2024
  4. Haimes and Jiang, Leontief-based model of risk in complex interconnected infrastructures, 2001
  5. Hallegatte, An adaptive regional input-output model and its application to the assessment of the economic cost of Katrina, 2008
  6. Carvalho, Nirei, Saito and Tahbaz-Salehi, Supply chain disruptions: evidence from the Great East Japan earthquake, 2021
05Take part

Take part in the work

Start from who you are.

06Questions

Questions, answers and key terms

Is the course free?
Yes. Every course and learning material of Risk Academy, led by the Nexus Consortium, is free to study, self-paced or with a cohort. Ordinary participation has no fee; paid work, internships and fellowships are separate arrangements.
What does completing a course give me?
A completion record: the course, its version, the date and what was assessed, private by default and shared by you. It stacks into discipline, department and programme achievements. A record states what was studied and assessed and does not certify competence; it is not a licence, a professional title or an employment status.
Where do the data and the places come from?
Every faculty teaches on a twin of a real place built from open data; each layer carries its provider, licence and date, and every result on the Academy states its source. Maps and figures are indicators for teaching, never an assessment of a place.
How do I take part beyond the course?
Form a competence cell of three to seven people, study a shared pathway, take a supervised assignment in the National Working Groups, or bring a cohort from your institution. For organisations.

Key terms

Term

Input-output model

A model of the flows of goods and services between sectors used to trace how output in one sector depends on others.

Term

Inoperability

The proportion by which a sector's output falls short of its planned level after a disruption.

Term

Chokepoint

A node or route in a network whose loss cuts off a large share of flows.

Term

Percolation

The process by which a network fragments as nodes or links are removed, used to measure robustness.

ReportsContribute

Contribute evidence from this page.

Reports is the Consortium's quarterly publication. What you know about this subject can become evidence, a case or a correction in the next edition, credited to you and published under CC BY 4.0 where it is your own work.

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