Earthquake Event Time vs. Update Time: Is It a New Quake?
Separate an earthquake’s origin time from a revised report and a refreshed feed. Use event identifiers and a fictional comparison to avoid duplicate earthquake headlines.
Three timestamps can appear in one feed
The USGS GeoJSON summary format separates a feed-level generated value from each event’s time and updated values. It also supplies an event identifier and event-page link. Keep those fields separate when reading a dashboard: a new feed response does not, by itself, establish a new earthquake.
Source: USGS GeoJSON summary fields ↗
A revision belongs to an existing event
Earthquake measurements can be revised. As a historical example—not breaking news—the USGS page for the 2011 Prague, Oklahoma earthquake records a later change in its magnitude from 5.6 to 5.7 in September 2016. A report changed years after the event; that revision was not a second earthquake on the revision date.
Source: USGS historical Prague earthquake page and revision note ↗
Compare records using identity, not headlines alone
In our fictional exercise, record TRAINING-A has an event time of 10:02 UTC and an update time of 10:08 UTC. A later copy retains TRAINING-A but shows an update at 10:21 UTC. Treat these as two versions to compare, not automatically as two earthquakes. Record what changed and retain the original event link. A similar place name alone is not a reliable way to establish identity.
Do not infer a second shock from a changed number
Our editorial check is to compare the identifier, event time, coordinates and source page together. If the identifiers differ, investigate the authoritative records before declaring either a duplicate or an aftershock. If only the retrieval time changed, do not write a new-event headline. A list sorted by recent updates can bring an older event back into view without changing when it occurred.
What to preserve when sharing
Save the event URL, event time with zone, measurement you are quoting and the report version or update time visible to you. Label a later correction as a revision. Keep confirmed impact reports separate from the earthquake measurements; a newly revised magnitude is not a new casualty count. If the current source is unavailable, describe your copy as a stored report rather than claiming it represents the latest assessment.
Put it into practice
| Field or example | Value or action | Meaning |
|---|---|---|
| TRAINING-A / first copy | Event 10:02; updated 10:08 UTC | One fictional event record. |
| TRAINING-A / later copy | Event 10:02; updated 10:21 UTC | Compare changes to the same record. |
| Feed refreshed | Generated 10:22 UTC | Does not establish another earthquake. |
| Different identifier | TRAINING-B | Investigate the source; do not deduplicate by place name alone. |
Official sources
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For an active emergency, follow the issuing agency and local authorities. Read our editorial policy.