A YouTube channel · with your host Gemma

Ground
Truth

Earth's hazards, on the evidence

Earthquakes, volcanoes, tsunamis, floods and the great ocean currents. Every video is the complete, honest account of one famous hazard: how scientists know, which part is settled, and what it means where you live.

Gemma, the channel's host, at her deskGemma · AI host
What you get

One famous hazard. The whole story.

The headlines give you a date and a scare. We give you the instruments, the papers, the arguments between the scientists, and the number everyone misquotes.

  • Real maps of the land and the seafloorEvery place on a physical atlas drawn from NOAA's elevation and seafloor data. You see where it is and why it matters.
  • The actual studies on screenThe paper that made the headline, who wrote it, and what other scientists answered.
  • Settled and unsettled, said plainlyWhat three independent lines of evidence agree on, and what nobody can tell you yet.
  • What it means where you liveThe official tools to look up your own coast, fault or flood zone, and the questions to ask of the next headline.
On screen

How the evidence looks

A cream relief map of the North Atlantic with a red current, a sea-temperature layer and labels
The atlasRelief, seafloor and real sea temperatures. A red line traces the current along its true course.
Archive portrait of an oceanographer with his name and role
The peopleThe scientists behind the work, on real archive photos.
A cross-section of the ocean floor with a surface current sinking near Greenland
The cross-sectionThe ground cut open along a real line, depth exaggerated and labelled.
Two journal articles side by side with a red not-equal sign
The papersWhen two studies disagree, you see both pages side by side.
A line chart of carbon dioxide at Mauna Loa since 1960
The recordMeasured series from NOAA and NASA, with the source on screen.
Three circular lenses labelled moorings, sea temperature and seafloor mud
Three ways of knowingThe independent lines of evidence, shown together.
A diagram comparing a block of water to the Statue of Liberty
The mechanismDiagrams on graph paper, with real objects for scale.
A map of northern Europe with modelled winter temperatures for London and Bergen
The numbers in placeModel figures, always labelled as model scenarios.
Method

How an episode runs

  1. The paradoxTwo places, one fact, opposite outcomes. Or an exact time and a countdown.
  2. The answer up frontWhat's happening, in the first half-minute, then the question that isn't settled.
  3. How it worksThe name taken apart, the mechanism in plain steps, the scale in familiar units.
  4. The headline studyWho claimed what, in which journal, and why it shocked people.
  5. Three ways of knowingIndependent evidence that shares no instruments and no assumptions.
  6. The correctionThe misquoted number, redone with the viewer, out loud.
  7. What would settle itThe measurement, the date and the competing models.
  8. Where you liveThe official source for your region and one thing to look up.
Coming up

On the docket

Alaska

The biggest earthquake in American history lasted 4.5 minutes

Faults & quakes
Colorado River

Everything we know about the Lake Mead crisis, and the state that's really in trouble

Water
N. California

Scientists are watching the Gorda Plate

Faults & quakes
Mid-South

Tornado Alley is moving east. Here's the map nobody shows you

Weather
Great Lakes

The Great Lakes have tsunamis, and almost nobody knows

Water
Lake Tahoe

A tsunami in the mountains: the fault under America's clearest lake

Faults & quakes
Gemma, the channel's host
Your host

Meet Gemma

Gemma is an AI presenter. Her face and her voice are generated. Every word she says is written from published research and official sources, and the sources for every video are listed in its description.

Sources, alwaysAgencies, journals and named researchers, with the year, for every number.
Never a predictionNo dates for disasters. Measurements and models are told apart.
Corrections, in publicWhen the science changes or we get something wrong, the fix goes in the description with a timestamp.
New hazard, new question

Which place should we look at next?

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