Major impact beats distance alone
A red or orange GDACS event can matter even farther away, while a green alert normally needs much stronger local relevance to clear the feed threshold.
Duplicate noise is reduced
USGS remains the detailed earthquake source; GDACS is used mainly for other major hazards so the radar does not repeat the same earthquake twice.
Source acknowledgement stays visible
GDACS cards identify the Global Disaster Alert and Coordination System and link to the original event.