Quakedle
Five questions about one real earthquake, read the way the USGS records it
Quakedle shows you one real earthquake as the United States Geological Survey recorded it, then asks five questions about that record. It is a reading exercise rather than a game about guessing where something happened.
How a round goes
The page opens with a briefing taken straight from the USGS record: the event identifier, the place label, and the time the event occurred, in UTC. Five questions follow, one at a time. You get a single attempt at each, the correct option and a short derivation rule appear immediately after you answer, and the round ends with a score out of five.
Four of the questions are fixed. They ask which descriptive class the magnitude falls in, which band the hypocentral depth falls in, which broad region the place label belongs to, and what the tsunami indicator on the record says. The fifth usually rotates by weekday, from Monday as the easiest through to Sunday as the hardest, dropping to an easier variant when the record lacks the data. It asks about the magnitude-type code, the count of Did You Feel It? reports, or whether this was the largest event in the USGS week around it, a comparison the game makes for you rather than showing you the week.
The bands, and why the region question is cautious
Magnitude and depth are arithmetic against fixed boundaries. Below M4.0 is minor, 4.0 to 4.9 light, 5.0 to 5.9 moderate, 6.0 to 6.9 strong, 7.0 to 7.9 major, and 8.0 or above great. Under 70 km is shallow, 70 to 300 km intermediate, and over 300 km deep.
The region question is the one that needed care. A USGS place label is a bearing and a distance from a settlement, and a place string on its own cannot identify a fault. So the game scores it against an authored table of 33 broad regions, read from specific place names down to general ones, with a fallback for events that do not resolve to any of them. The plate names follow USGS plate maps, and the accompanying notes stay deliberately general about what is moving and where.
Where the data comes from
Event details come from the U.S. Geological Survey Earthquake Hazards Program GeoJSON and FDSN services. USGS-authored data are public domain. The regional context cites the USGS 'Tectonic Plates of the Earth' map, and every finished puzzle links to the original USGS event page so you can read the record for yourself.
The frozen calendar covers 45 days, and behind it sits an archive of 365 events chosen to spread across regions rather than to rank by size alone.
What the decode covers, and what this is not
The end state lays the whole record out in order: magnitude, magnitude type, depth, region, tsunami indicator, felt reports, alert level, the plates involved, and a short note on the tectonic setting. The tsunami indicator is the part worth reading slowly. It records whether the survey associated a tsunami indicator with that event. It is not a forecast, and it is not an all-clear.
These are real earthquakes, and some of them caused deaths and damage. Quakedle is an educational game about how such an event is reported, and and its privacy page states that the event details and tsunami indicators shown here must not be used for emergency decisions. For that, follow your local authorities and current USGS notices.
Questions
Is it the same puzzle for everyone?
Yes. One event a day, the same one for every player, rolling over at midnight UTC. The frozen calendar covers 45 days.
Do I need an account?
No. Nothing is stored on a server about you. Your score history and streak are kept in your browser's local storage, and clearing site data for the domain clears them.
Do I need to know any seismology?
Not for the magnitude, depth and felt-report questions: the value is printed in the prompt and the option labels carry the boundaries, and the derivation rule is shown once you answer. The region question rewards knowing roughly where a place name sits on the map, which is why the decode ends with a note on the tectonic setting. The tsunami question has no on-screen value to work from at all.