Disasters and hazards

GDACS disaster alerts: Orange and red alerts from the Global Disaster Alert and Coordination System: floods, tropical cyclones, droughts, wildfires and volcanic activity. Green alerts are not reported — they are the great majority of what GDACS emits, eighty-five wildfire alerts in a single week in the week this source was built, and green means little or no humanitarian impact is expected. Earthquakes are not reported from GDACS at all: GDACS takes them from USGS, which this service already reads directly under its own magnitude rule, and publishing both would put one earthquake on the site twice from two records that can diverge after revision. An alert level is not a measurement of the hazard and not a count of anyone harmed. It is GDACS's automatic estimate of the humanitarian impact a hazard of that size is likely to have, calculated from the hazard's extent and the population and vulnerability of the area, and published within minutes of a detection. No brief here reports deaths, injuries, displacement or damage, because the record used does not establish them. A severity figure is published only where GDACS supplies a unit whose meaning has been checked. Floods and volcanic alerts arrive with a severity of zero and no unit at all, so no severity is shown for them and the brief says why. GDACS's own sentence describing a severity is never reproduced: for tropical cyclones it pairs a storm classification with a wind speed that contradicts it. GDACS states that its information is indicative, that it should not be used for decision-making without other sources, and that it does not replace any warning issued by a national or local authority. That statement appears on every brief.