Start with the message rather than the epicentre
The National Weather Service alert explanation distinguishes warnings, advisories, watches and information statements. These categories are not interchangeable earthquake labels. A warning concerns a potentially damaging tsunami; an advisory concerns dangerous currents or waves; a watch indicates a possible later impact. Read the full official message and its affected coastline rather than inferring the category from earthquake magnitude.
The US Tsunami Warning Centers site presents official messages together with map context. Identify the issuing centre, bulletin time, update and geographic coverage. A distant earthquake can appear on the map without placing every US coastline under an alert. An older message may also remain available for reference after a newer bulletin changes the assessment.
Use the correct map layer
The site's map-reading help explains earthquake, alert, observation, forecast and monitoring-location layers. A water-level station icon marks a monitoring location, not a statement that a dangerous wave is occurring there. A forecast and a water-level observation are different products. Always inspect the selected layer and associated timestamp before describing what a symbol means.
For example, a screenshot with both earthquakes and water-level stations can look like a single collection of incident markers. Keep the legend visible and describe each type separately. If the viewer offers previous messages, distinguish the archive from the latest update. Browser-local times also need a label when a screenshot is shared with someone in another US time zone.
Do not treat an empty global map as an all-clear
The PocketWorld tsunami overview provides available bulletin and earthquake context. It is not the official warning system and does not guarantee complete current coverage. A missing record, delayed source or retained snapshot cannot establish that no local alert exists. The absence of a marker is a data-coverage statement, not an emergency instruction.
For an explanatory comparison, record the event identifier, earthquake time, latest bulletin time and affected coastline. Open the authority's current message directly; use PocketWorld to understand the geographic relationship, not to decide whether a beach or harbour is safe. Local emergency instructions and official warning channels take priority. This article is not an operational checklist: there may not be time to browse maps during a nearby event. Its purpose is to prevent research, news summaries and saved screenshots from confusing an earthquake location, a modelled arrival or a monitoring station with the legal and practical meaning of an official coastal alert.
Data sources
References are linked beside the explanations above. This evergreen guide does not report current incidents.