Above us.
Beneath us.
How do we know?

Choose a layer. Open its evidence.

A journey through the air.

The archived profile is labelled 11 March 2011, nominal 00:00 UTC. Its release field says 23:30, interpreted here as the preceding UTC date. This is not a simultaneous column: the instrument ascends over time and drifts horizontally.

Reported geopotential heights are not geometric altitudes. Variable-pressure levels often lack height. Missing and QA-removed values become null, never zero. No intermediate height is invented; gaps between plotted levels are not new observations. Header coordinates are fixed-station catalogue coordinates, not a reconstructed balloon trajectory. No chemical composition or aerosol concentration is measured by this extract.

Listen through the ground.

The 2011 Great Tōhoku earthquake is catalogued at magnitude 9.1, with preferred origin time 05:46:24.120 UTC on 11 March. The selected reviewed product associates 657 arrival picks with that origin. Its reported depth is 29 km and is explicitly marked operator assigned. The assignment flag does not explain which constraints were used to choose the depth. The origin time, location and phase identifications are analysis outputs; they are not all direct instrument readings.

These are catalogue picks associated with one preferred origin, not raw waveforms. Phase labels, distances, origin and residuals depend on catalogue analysis. Zero-weight picks remain present and are visibly distinct. Missing S picks in a P-dominated compilation do not demonstrate absence of S waves. Arrival count, distinct station labels and the origin reported station count are different fields. One earthquake does not independently establish core composition or reconstruct every interior layer.

Materials gather. Layers develop.
Rocks preserve clocks.

Three witnesses to the same question.

For an interior claim, seismic behaviour, material experiments and gravity or rotation can supply different constraints. Three websites repeating one catalogue do not create three independent measurements. The two datasets here are introductory examples; their dates do not establish an atmosphere–earthquake connection.

What would deepen this explorer?

1. Retrieve original seismic waveforms, instrument responses and station metadata for selected arrivals, then verify phase picks.
2. Compare additional earthquakes across different paths and hold out events from any model fitting.
3. Add a named rock or borehole record with specimen identity and laboratory measurements.
4. Add original ionosonde and particle-density records above balloon range.
5. Add original isotope measurements and their uncertainty before reproducing a geological age.

These tasks remain open. No new interior inversion, global atmospheric reconstruction or geological date is claimed.

Follow the original records.

Reviewed 11 November 2026. Public observations, catalogue interpretations and explanatory references have separate roles.

1. NOAA NCEI · IGRA station archive ↗

   One 104-level profile extracted from the station period-of-record file, nominal 2011-03-11 00 UTC. Original archive preserved privately; bounded profile extract published.

2. NOAA · IGRA record format ↗

   Fixed-width units, missing values and processing flags used in extraction. A/B flags describe different climatological checks; blank does not mean unmeasured.

3. NOAA · IGRA station metadata ↗

   Station identity and current catalogue coordinates; historic station location changes were not reconstructed.

4. USGS · 2011 Great Tōhoku earthquake ↗

   Preferred event/origin metadata. The event is Mw 9.1; the selected phase product is a later reviewed catalogue product, not a contemporaneous raw recording.

5. USGS · reviewed QuakeML phase product ↗

   657 associated arrivals, retained with original phase names, weights, pick UTC and residuals. Preferred origin depth is explicitly operator assigned.

6. USGS · The Interior of the Earth ↗

   Historical explanatory overview of the combined seismic, gravity, magnetic, heat-flow and laboratory evidence. Not a raw dataset; older illustrative estimates require context.

7. USGS · Inside the Earth ↗

   Crust, mantle, liquid outer core and solid inner core; mechanical lithosphere and asthenosphere are a different classification. Educational synthesis, not independent raw evidence.

8. NASA · thermal layers of the atmosphere ↗

   Approximate, variable thermal layer ranges for the schematic. No sharp universal upper atmospheric surface is defined.

9. NOAA · ionosphere ↗

   Charged particles and radio propagation; an overlapping electrical region rather than another solid or thermal shell.

10. NASA · A Rocky Planet Forms ↗

    Accretion and differentiation as a formation explanation. Educational model, not a measurement made by this explorer.

11. NIST · how radiometric dating works ↗

    Isotope decay and the approximate 4.54-billion-year planetary age. Slider is an illustration; no original laboratory isotope measurements analysed here.

12. EarthScope · seismic data access ↗

    Next route to original waveforms and station responses. A free account may be needed; raw waveforms not downloaded in this pilot.