Mexico shakes a lot. The country sits on one of the world's more active seismic zones, and small to medium quakes rattle parts of it regularly, usually followed by a string of aftershocks. For travellers, that raises a practical language question: which word should you use when the ground moves?

Mexicans have three words for it, and picking the right one is more about feel than science. "Temblor" — literally a tremor — is the everyday word, used for the small and medium shakes that happen often. "Terremoto" is reserved for the serious ones, and people would look at you strangely if you called anything less by that name. The quakes that devastated Mexico City and the south in September 1985, and again in September 2017, are firmly in terremoto territory, as is the big April 2013 quake on the Guerrero–Oaxaca border.

The third option, "sismo," is the technical one. Geologists, government officials and plenty of journalists use it because it just means "seismic event." But you'll never hear it in casual chat — nobody turns to a friend and asks "did you feel the sismo?" It's the word of press releases, not conversation.

Here's the interesting part: there's no fixed magnitude or damage threshold separating a temblor from a terremoto. The distinction is subjective, and it often depends on where you were when it hit. Someone on the ground floor of a building perched on solid rock might shrug off a shake as a temblor, while a person on the tenth floor of a tower built on Mexico City's soft ancient lake bed — where the swaying is dramatically amplified — would call the very same event a terremoto. Same quake, different word, and both would be right.

Why should a traveller care? First, it helps you read the room. If locals casually say "fue un temblor," the mood is calm; if the word "terremoto" is circulating, take it seriously. Second, it's a useful lens on how Mexicans live with seismic activity: frequent enough that it's woven into everyday language, with a shared understanding of when a shake is routine and when it isn't. Damage from larger quakes tends to mean cracked walls and ceilings, broken glass and harm to roads and street furniture, mostly near the epicentre — so if you're travelling in a rural area close to a significant quake's epicentre, expect possible transport disruption.

If you're visiting Mexico City, it's worth knowing that the capital's downtown sits on that old lake bed, which is exactly why quakes that barely register elsewhere feel intense there — and why the city has drills, alarms and well-rehearsed routines. Knowing the vocabulary, and the intuition behind it, means you'll understand both the warnings and the reassurances.

So: temblor for the everyday wobble, terremoto for the ones people will remember by year, sismo for the news bulletin. Use them correctly and you'll sound like you've been paying attention — because in Mexico, everyone has.