Earthquake record › methodology

How This Earthquake Archive Is Collected

One source, one fetch a day, sealed and never rewritten.

The source

We fetch exactly one file: the USGS all_day summary feed. It is a work of the US government and is in the public domain. It contains the last 24 hours of events worldwide and is overwritten continuously.

The cadence, and what a missing day means

We seal one copy per day. We hold 45 seals across 47 calendar days, 2026-06-23 to 2026-08-08. The gap between those two numbers is disclosed, not smoothed:

Because the window is 24 hours and the seal is daily, a missed day is not just a missing page — the events that lived and died inside that window are absent from the archive permanently. They cannot be backfilled, by us or by anyone, and we will not pretend a later fetch recovers them.

The published day-page window

The published day-page window currently runs from 2026-06-24 through 2026-08-08 and contains 44 daily pages. The sitemap is capped at 100 scope pages: 56 state, state-by-magnitude, magnitude, or event-type pages, plus the newest 44 qualifying daily seals. 1 older qualifying seal is retained in the archive totals but sit outside the current published day-page window.

What we do not do

• We do not normalise magnitudes. USGS publishes 10 different magnitude types across the 10,578 events in this archive — ml (6,302), md (3,218), mb (862), mww (157), mw (14), mwr (13), mb_lg (6), mh (2), mlr (1), mun (1), plus 2 events with no magnitude type published. They are not interchangeable and we never average or convert them. Every magnitude renders exactly as published.
• We do not geocode. A state is assigned only from the text after the last comma of the place string, from the table below. Coordinates are sealed but never used to infer a jurisdiction.
• We do not fill gaps. A day we did not seal is a 404, not an interpolation.
• We do not publish the collector's row counts as event counts. The clock's own log counts its fetch bookkeeping row alongside the events. Every count on this surface is a count of sealed events.

The complete place-tail table

Every mapping used anywhere on this surface. A tail not listed here is counted as unassigned and never guessed at. USGS writes both the abbreviation and the full name for some states, which is why both appear.

Tails we refuse to resolve

These name a US state and something else. The archive holds one event under each reading, which is exactly why the tail cannot decide.

Daily pages in the published window

• 2026-06-24
• 2026-06-25
• 2026-06-26
• 2026-06-27
• 2026-06-28
• 2026-06-29
• 2026-06-30
• 2026-07-01
• 2026-07-02
• 2026-07-03
• 2026-07-05
• 2026-07-06
• 2026-07-07
• 2026-07-08
• 2026-07-09
• 2026-07-10
• 2026-07-11
• 2026-07-12
• 2026-07-13
• 2026-07-14
• 2026-07-16
• 2026-07-17
• 2026-07-18
• 2026-07-19
• 2026-07-20
• 2026-07-21
• 2026-07-22
• 2026-07-23
• 2026-07-24
• 2026-07-25
• 2026-07-26
• 2026-07-27
• 2026-07-28
• 2026-07-29
• 2026-07-30
• 2026-07-31
• 2026-08-01
• 2026-08-02
• 2026-08-03
• 2026-08-04
• 2026-08-05
• 2026-08-06
• 2026-08-07
• 2026-08-08

Every fetch, in full