What GDACS does differently from event catalogs
The Global Disaster Alert and Coordination System (GDACS) is a joint initiative of the United Nations and the European Commission designed to improve alerts and coordination during the first phase of sudden-onset disasters. Unlike event catalogs that simply record that something happened, GDACS assesses the potential humanitarian impact and assigns alert levels: green (low), orange (moderate), or red (high expected humanitarian impact).
This distinction matters enormously. The world experiences thousands of earthquakes, storms, and wildfires every year, but only a small fraction pose significant risks to human populations, infrastructure, or international coordination needs. GDACS filters the noise by evaluating each disaster against population exposure, vulnerability models, and historical impact data.
How GDACS alert levels are determined
GDACS uses automated models that combine hazard parameters (earthquake magnitude, storm wind speed, flood extent) with exposure data (population density, infrastructure maps, vulnerability indices) to estimate potential impact. A magnitude 6.5 earthquake under a city of 10 million people will receive a higher alert level than the same magnitude under uninhabited ocean.
The models are imperfect but useful. They provide a first approximation within minutes of an event, well before field assessments are possible. This early estimate helps humanitarian organizations decide whether to activate response teams, pre-position supplies, or begin coordination. For monitoring platforms like PlanetSentry, GDACS adds a layer of significance context that pure sensor data cannot provide.
- Green alert: low expected humanitarian impact, no international coordination expected
- Orange alert: moderate expected impact, regional attention warranted
- Red alert: high expected impact, international coordination likely needed
GDACS coverage and data feeds
GDACS covers earthquakes globally (M5.0+), tropical cyclones in all ocean basins, floods in most countries, and volcanic eruptions. Each alert includes an estimated affected population, alert level, and links to detailed impact assessments. The data is published through RSS feeds, email alerts, a web portal, and an API — all freely accessible.
PlanetSentry integrates GDACS as a separate overlay layer rather than merging it into the core event catalog. This preserves the distinction between 'something happened' (event data) and 'this matters for people' (humanitarian assessment). Users can toggle GDACS alerts on or off and compare them against the base event map to quickly identify which incidents deserve deeper attention.
Why journalists and researchers should watch GDACS
If you cover natural disasters or conduct humanitarian research, GDACS alerts are one of the fastest ways to identify events with significant human impact. The alert system activates within minutes for earthquakes and within hours for cyclones and floods, providing early impact estimates before field reports arrive.
The alert archive also enables trend analysis: which regions experience the most red alerts, how frequently do orange alerts escalate, and whether alert patterns correlate with climate variables. PlanetSentry's news feed now includes GDACS RSS items alongside NASA and USGS data, creating a unified monitoring surface for anyone tracking global disaster risk.