Natural Disaster Tracking

The Natural layer combines two authoritative sources for comprehensive disaster monitoring, providing real-time alerts with severity assessments and satellite-derived event detection.

GDACS (Global Disaster Alert and Coordination System)

UN-backed disaster alert system providing official severity assessments:

Event Type	Code	Icon	Sources
Earthquake	EQ	Red circle	USGS, EMSC
Flood	FL	Wave	Satellite imagery
Tropical Cyclone	TC	Cyclone	NOAA, JMA
Volcano	VO	Volcano	Smithsonian GVP
Wildfire	WF	Fire	MODIS, VIIRS
Drought	DR	Sun	Multiple sources

Alert Levels:

Level	Color	Meaning
Red	Critical	Significant humanitarian impact expected
Orange	Alert	Moderate impact, monitoring required
Green	Advisory	Minor event, localized impact

NASA EONET (Earth Observatory Natural Event Tracker)

Near-real-time natural event detection from satellite observation:

Category	Detection Method	Typical Delay
Severe Storms	GOES/Himawari imagery	Minutes
Wildfires	MODIS thermal anomalies	4-6 hours
Volcanoes	Thermal + SO2 emissions	Hours
Floods	SAR imagery + gauges	Hours to days
Sea/Lake Ice	Passive microwave	Daily
Dust/Haze	Aerosol optical depth	Hours

Multi-Source Deduplication

When both GDACS and EONET report the same event:

1. Events within 100km and 48 hours are considered duplicates
2. GDACS severity takes precedence (human-verified)
3. EONET geometry provides more precise coordinates
4. Combined entry shows both source attributions

Filtering Logic

To prevent map clutter, natural events are filtered:

• Wildfires: Only events < 48 hours old (older fires are either contained or well-known)
• Earthquakes: M4.5+ globally, lower threshold for populated areas
• Storms: Only named storms or those with warnings