Linked from
The 19 pages that link to Early warning system, each with the reason it gives.
LaharRelated: Sensors can detect lahars and provide time for downstream communities to evacuate.
Natural hazardRelated: Warnings can give exposed communities time to evacuate or take shelter.
Extreme weatherRelated: Warnings reduce harm when extreme weather is forecast in time.
DisasterRelated: Warnings can reduce harm when alerts reach people in time to act.
Military intelligenceRelated: Warning intelligence can give forces time to prepare for an attack.