Identify the measure
The US Geological Survey distinguishes magnitude, which describes the earthquake’s size, from intensity, which describes effects at a location. One earthquake can therefore have many intensity values across the affected area. A local intensity report is not a competing estimate of the event’s magnitude.
Write the scale name beside the number. A plain number without its scale can invite a false comparison, especially when a map uses Roman numerals or a colour legend while a headline uses a decimal magnitude.
Keep the place attached
For an intensity value, identify the location and whether the product is observed, reported or modelled. USGS describes its Did You Feel It? system as using public reports to contribute to intensity information. Such a map answers a different question from the event’s epicentre and magnitude summary.
A dramatic witness video shows conditions within its own frame and time. It does not by itself establish the intensity everywhere in the city or the total extent of damage.
Read updates as updates
USGS explains that different agencies may calculate different magnitude types and use different data. Early estimates can also be revised as analysis develops. Before treating two broadcast numbers as a contradiction, compare the event identifier, publication time, agency and measure. Keep an early clip’s original timestamp when sharing it alongside a later update.
Do not combine figures from nearby earthquakes simply because the place names look similar. Match origin time and the source’s event record.
Check depth and location labels independently; neither is another magnitude scale.
Make a precise viewing note
A useful note says that the broadcaster reported a particular magnitude estimate at a stated time, while an intensity map described local shaking using its own scale. Preserve the original agency link and map legend. Avoid calculating damage or personal risk from a single number or a clipped video. This article explains media terminology and supplies no current earthquake assessment; for current conditions and actions, use the relevant official agencies and local instructions rather than an archived television report.
Related questions
Can intensity vary for the same earthquake?
Yes. It describes effects at particular locations.
Does a revised magnitude mean the footage was false?
No. Compare timestamps, data and magnitude methods before drawing that conclusion.
Sources and scope
Scope notes distinguish published documentation, supplied information and editorial methods. They do not report a hands-on service test.
- USGS: magnitude and intensity — Primary definitions distinguish event size and local effects.
- USGS: Did You Feel It? background — Explains public-report intensity information.
- USGS: agency magnitude differences — Explains different magnitude types and regional/global data context.
