Magnitude does not describe every location
A magnitude value characterizes an earthquake, while local shaking varies across the affected region. The USGS ShakeMap overview explains its ground-motion and intensity products. Read the displayed quantity and legend before using a colour to describe a town. A shaking estimate, acceleration field and epicentre symbol are not three versions of the same measurement.
For example, two cities at similar distances from an epicentre need not have identical shaking estimates. Inspect the event-specific map instead of drawing equal-distance circles and assigning them a single intensity. Keep the event identifier attached to the product, especially when a sequence includes multiple nearby earthquakes. Matching only the place name or magnitude can connect a screenshot to the wrong event.
Compare three different kinds of evidence
Did You Feel It? collects people's reports of shaking. Its coverage depends on participation; a place with few reports is not thereby proven to have experienced no shaking. Read the report count and geographic grouping alongside the displayed intensity. A crowdsourced response map should not be presented as a complete census of damage or affected residents.
USGS PAGER provides estimates of potential earthquake impacts. Those estimates are not a verified list of casualties or damaged buildings. Keep them separate from instrument readings and felt reports. In a research note, label each product explicitly: ShakeMap for estimated ground shaking, DYFI for reported experience and PAGER for estimated impacts.
Check the product version and units
Earthquake solutions and associated products can be revised as additional information becomes available. When comparing two images, check the event time, product generation time and version. An early downloaded map may legitimately differ from the product currently attached to the event. Preserve both timestamps if you are explaining a revision instead of silently replacing the early estimate.
The PocketWorld earthquake overview displays available source-labelled event information. It does not reproduce every ShakeMap, DYFI response grid or PAGER estimate. Its marker is geographic context, not a building-level shaking assessment. Use the official event's product page for the complete legend and explanatory material; our magnitude-versus-intensity guide covers the basic distinction.
For a shareable summary, record the USGS event identifier, product name, relevant units, version time and link. Avoid statements that a whole county suffered the same shaking because a small-scale image uses one broad colour. Do not turn an impact estimate into observed damage, or an absent felt report into an all-clear. This page explains how to interpret public products; local emergency instructions and qualified assessments remain separate from any global map.
Data sources
References are linked beside the explanations above. This evergreen guide does not report current incidents.