Tremo user guide

Everything Tremo does, screen by screen, on the web and in the app. Read it start to finish or jump to what you need from the contents. It is updated with every change to Tremo.

1. Getting started

Tremo shows you earthquakes in real time, works out how strongly you would feel them where you are and alerts you only when it really matters to you. It runs in the browser (web) and as an Android and iPhone app; almost everything is the same in both, and where it differs, this guide says so.

Your location. Tap «Use my location». It stays on your phone: Tremo uses it to work out the intensity you would feel. If you'd rather not share GPS, you can pick the place by hand later in My Tremo → Places.
Alerts. Tap «Turn on» and allow notifications. Without this permission Tremo can only alert you while the page is open.
Install. On the web, Tremo installs as an app (opens instantly and works offline). In the app it is already installed, so this step doesn't appear.

The top bar is always there: the logo (back to Home), a status dot (green = data up to date; amber = an official source is slow; red = offline, showing the last download; tap it to read the details), the gold ⭐ Plus button with its price (it disappears once you have it), the red SOS button, your avatar (My Tremo) and the ☰ menu.

At the bottom, the five tabs: Home, Map, Lab, Community and Learn.
In the ☰ menu, in two groups separated by a line: yours (My Tremo, Tremo Plus, Emergency and Tremo Network) and reading and learning more (Articles, User guide, Download the app —web only— and About), plus Contact and Language. On a computer, everything is in the left sidebar, with the five tabs at the top and a line between each group.
Language: Tremo speaks 14 languages. Change it from ☰ menu → Language (on a computer, the globe in the top bar). Lessons, articles and this guide are in English and Spanish.

Want to start right now? Do three things: share your location, turn on alerts and tap «Run a drill» in My Tremo to see and hear what a real alert would be like.

2. Home: what's happening now

At the top, Tremo's mascot sums things up: how many earthquakes there were within 300 km of you in 24 hours, the largest one nearby and the largest in the world. Below it, three figures: Near · 24 h, Largest near and World · 24 h.

Ask Tremo (with an account): type a question about earthquakes or preparedness and Tremo answers, linking the course lesson that explains it. 40 questions a day (120 with Plus).
Alerts with the app closed: if you haven't turned them on yet, the «Turn on alerts» button is here.
Seismic activity: the earthquake list with its «Near you», «World» and your-country tabs. Filter by minimum magnitude and sort by time, magnitude or distance.
Each row shows the magnitude (with its colour), the place, how long ago, the distance to you and the intensity you would have felt. Tap it to open its page.
The list shows 12 at a time: «Show more» brings the next ones. «See all N on the map» opens them all on the Map.

The list refreshes on its own every 20 seconds while the page is open. No need to reload.

3. How alerts work

Tremo never makes up earthquakes: it alerts you with data published by official seismic networks (the national networks of 18 countries —such as the Colombian Geological Survey, the Geophysical Institute of Peru, Mexico's SSN, Chile's CSN, Venezuela's FUNVISIS, the Japan Meteorological Agency or Italy's INGV—, Europe's EMSC, which gathers some 65 agencies, the USGS and Germany's GFZ), plus official early warnings and the Tremo Network when they are active. If two networks publish the same earthquake, you get a single alert, with the data from the network of the country where it happened: each national network leads in its own country, then EMSC, then the USGS and, last, GFZ.

Tremo finds out within seconds: it constantly watches each network's latest earthquake (EMSC sends it instantly) and, as soon as one publishes a new one, it fetches it and decides the alerts right then. How long each network takes to publish (the SGC reviews every quake first: about 8 minutes for M4+) is up to them.

There's a backup: if a country's network doesn't respond, EMSC, the USGS and GFZ continue (slower, and only with the larger quakes). That's how it works with the SGC in Colombia or the JMA in Japan. A notice that arrives more than 20 minutes late is no longer an alert: up to 2 hours it reaches you as information, silently.

What decides whether you're alerted isn't magnitude alone but the estimated intensity at your places (Mercalli scale, using the 2012 Allen, Wald and Worden equation): distance, depth and magnitude together. It's the same rule for everything Tremo alerts about: official networks, the Tremo Network and people's reports.

From Cali, an M6 in Meta (331 km) arrives at intensity II-III: barely felt, so you get a short notice, no siren (unless you turned it off). The same quake in Tolima (181 km) or Chocó (249 km) arrives at III or more: felt, and you get an alert with sound. In La Guajira (984 km), not even an M7 would be felt.
Three levels. 🔔 Alarm (siren; in the Android app, full screen even with the phone locked): the quake reaches what you chose and you'd feel it. 🔉 Notice with the details (where it was, how many km from your place, the intensity and the depth), with a normal sound and no siren: it doesn't reach what you chose, but you'd feel it because of distance and depth; also what would barely be felt (intensity II½ to III), with a single chime, unless you turn off «Notices for barely felt quakes» (they're few: 3 or 4 a month in Cali or Bogotá). 🔕 Silently, as information: what you asked for but wouldn't be felt (a distant quake or an M7 in another country). An earthquake in Chile never makes a phone ring in Colombia.
Example: with the alarm at M4.5, an M3.8 14 km from Cali reaches you as a notice with its details (intensity III, weak); an M4.6 in the same spot sounds the alarm.
Strong shaking, always. If shaking will be strong at your places (intensity VI or more), the alarm sounds whatever your filter says.

At the top: the kind of alert (strong earthquake near you, reported earthquake or drill) and the magnitude in large type.
The data: how many km from your place, the intensity you would feel (Roman numeral plus description) and the depth.
The countdown: only shown if the strong wave (the S wave) hasn't reached your place yet. If it already has, Tremo doesn't pretend to warn you in advance.
The three steps: Drop, Cover and Hold on.
The buttons: «See map», «I felt it» (tell us what you felt: it helps map where it was felt) and «Close».
The notice (what you'd feel without reaching your alarm) doesn't cover the screen: it's a card at the top with the same details, «See map», «I felt it» and the X to close it. With the app closed it arrives as a notification with all the details.
With the alarm, the siren sounds (or the sound you chose), the phone vibrates and Tremo's voice reads the alert in your language. In the Android app, a silent summary also stays in the notification bar (where it was, how many km from your place, the intensity and the depth), to check once it's over.

An earthquake first releases the P wave (fast and weak) and then the S wave (slower, the one that shakes). Official networks take from a few seconds to a few minutes to publish an earthquake. If you're far from the epicentre, the alert can reach you before the S wave; if you're very close, it usually arrives after. Early warnings exist to win those seconds (see Tremo Network).

The blue notice is different: it says «N people report an earthquake» when many people in many places tap «It's shaking!» at the same time and another source backs it up. No siren, and it always says «unconfirmed». See the «It's shaking!» section.

Tremo does not predict earthquakes and nobody can. If someone tells you «there will be a big quake tomorrow», it's false. Your country's official alerts (SASMEX, ShakeAlert, phone emergency alerts) still come first: keep them on; Tremo complements them.

4. Setting up your alerts

Everything is in My Tremo → Alerts (the avatar in the top bar).

Alerts on: the main switch. With the page open, alerts sound and show on screen.
With the app closed: «Turn on» subscribes this phone or browser to get alerts with the screen off. «Test» sends one from the server: close the app and it should arrive within seconds. «Turn off» removes it.
When should we alert you? «Smart» (recommended): the alarm sounds by the intensity you would feel; choose from which level (II to VI; default III, «felt indoors»). «Manual»: choose a minimum magnitude (from M2) and maximum distance (default M4.5 within 300 km); the alarm sounds for what reaches that and you'd feel. In both, what you'd feel below your choice arrives as a notice with the details, no siren, and what you wouldn't feel arrives silently. Below M2 (M2.5 outside some countries) networks don't publish in time.
Notices for barely felt quakes (on): a short notice, no siren and a single chime, when a quake would barely be felt at your places (intensity II½ to III). Just a few a month; turn it off if you don't want them.
Major earthquakes worldwide: information about any M7+ earthquake on the planet; it arrives silently if you wouldn't feel it.
Sound: siren, bell, pulses, voice only, vibration only or silent; volume, Tremo's voice and vibration. «Test sound» and «Run a drill» let you hear it first.
Quiet mode: hours when it won't sound (for example 23:00 to 06:00), unless the intensity is at or above the level you choose (default V, strong). It also applies to early warnings and blue notices.

The rule in one line: alarm for what you chose and would feel, a notice for what you'd feel below it (or barely), silence for what you wouldn't feel, and always the alarm if shaking will be strong.

Further down, Will alerts reach me? checks this device point by point: compatible browser, app installed, notification permission, subscription, alert server, watched places and sound. In the app it adds: full-screen alarm, sounding in «Do Not Disturb», no battery limit and the Tremo Network sensor. If Android closes the sensor to save battery or renews the phone's registration for alerts, Tremo starts it again by itself: you don't have to turn anything on again. Each red item has a button to fix it, and «Set up step by step» walks you through everything missing, one at a time: what you'll see, what to tap and, when you come back, whether it's on. On Android, Google's Earthquake alerts (they warn seconds before the shaking) can't be read by any app: when you return from their setting, Tremo asks whether they're on and marks them green if you say yes.

On iPhone and iPad, in the browser, you first have to add Tremo to the home screen (Share → Add to Home Screen) and open it from there: Apple allows no other way to receive alerts. The App Store app doesn't need this.

5. Your watched places

Tremo watches your location and up to 4 more places: work, your children's school, your parents' house… It alerts you for whichever would shake hardest and tells you which one.

Open My Tremo → Places.
Current location: shows how it was obtained (GPS, approximate from the internet or chosen by hand). You can update it or «Forget location».
Add a place: type a city or address in «Search a city or address», tap «Add» and pick the right result.
To remove a place, use its delete button.

Your places are stored on your phone and, if you turned on alerts, also on the server (coordinates only, to decide whom to alert). If you sign in, they travel with you to your other devices.

With no place at all, Tremo can't know whether you would feel an earthquake: the check marks it in red.

6. The map

Each circle is an earthquake: size shows magnitude, and so does colour (or depth or age, if you change it). Those from the last 3 hours pulse. Tap one to see its card (the map moves so it ends up centred and fully in view), and from there «Details» or «See how the waves travelled».

Moving it: inside the page, with two fingers (one finger keeps scrolling the page, so you never get stuck in the map). In full screen, one finger is enough. On a computer, drag with the mouse and zoom with Ctrl + wheel (⌘ + wheel on Mac).
Map buttons: zoom in and out, point north (drag it to tilt), globe or flat view, go to my location, full screen and the 3D button (terrain; off at first, and Tremo remembers if you turn it on).
Layers: base map (satellite by default, automatic, light, dark or terrain), tectonic plates, «Where it was felt» (people's reports) and density.
Period and filters: last 24 h, 48 h, 7 days or 30 days, and minimum magnitude.
Earthquakes on the map: the table under the map; sort it by tapping the column headings.
History as CSV: download earthquakes for 7 and 30 days (every magnitude, from Tremo's 21 sources), 1 year (M2.5+), 5 years (M4.5+) or 10 years (M5+), worldwide or for one country, or the daily summary. Each quake has UTC and your device's time, the magnitude and its type, depth, place, country, network, whether it's reviewed, and its link.

On phones with little memory Tremo switches on lite mode by itself (simpler map, no globe or 3D). You can turn it on or off in My Tremo → Account.

7. Watching the waves travel

From an earthquake's card on the map, or from its page with «See the waves on the map», Tremo draws how the P and S waves spread out from the epicentre.

The data box always stays visible, at the top left, above the map: the seconds elapsed and, if you shared your location, when the P wave and the S wave reached you (and whether it would barely be felt there).
The rings fade out where nobody feels the earthquake anymore, based on its magnitude and depth (the same intensity estimate the alerts use): an M4 fades within a few tens of kilometers and an M7 after hundreds. The waves keep traveling, but only seismographs record them; the box tells you how far it is felt.
If the waves are still traveling you'll see «since the earthquake (real time)». Otherwise it replays in about 10 seconds: a small earthquake at real speed (×1) and a big one sped up (×8, for example); the box shows the speed. The page scrolls to the map and the epicentre sits in the part the box leaves free.
In a deep earthquake the waves take a while to rise to the surface (from 100 km, about 14 s the P wave and 25 s the S wave): the rings appear when they get there, the box explains it meanwhile and that wait goes by fast (×20). If almost nobody felt it, the rings are faint.
The times come from the IASP91 Earth model, the seismologists' reference (Tremo never gives a wave more than 1 s later than that model), and when it reached you only shows if you are less than 3,000 km away.
The box's red × button stops the replay and closes it.

It's the best way to understand why alerts arrive earlier in some places and later in others: the S wave travels about 3.5 km per second.

8. An earthquake's page

Map with the epicentre and the area where it was probably felt (noticeable, II+, and felt, III+).
Earthquake data: magnitude and its type, depth, time, coordinates, source (linking to the official network) and status: «Automatic» (the network's first estimate) or «Reviewed» (checked by a person). Automatic ones may change magnitude and location.
For your location: the distance, the estimated intensity (±1 level: the ground where you are can amplify or dampen it) and how long the S wave took to reach you.
Did you feel it? pick one of 7 levels for what you felt; your report joins the «Where it was felt» map.
Aftershock probability for the next 7 days, for significant earthquakes.
What should I do now? the steps after an earthquake, and a button to share it.

9. The forecasting lab

The lab doesn't predict earthquakes: it gives probabilities using public scientific methods and publishes its hits and misses.

Choose the region in its search box: type the name (accents optional) of one of the world's regions —including Ica / Nasca, southern Peru and northern Chile— or of any city (200 km around it), or tap the field to see them all and «My zone» (200 km around you); the magnitude (M4.5+, M5+, M6+ or M7+) and the window (24 h, 7 days, 30 days or 1 year).
Read the Combined probability and whether it is higher, similar or lower than usual for that region.
Compare the models: Historical (the long-term average), Aftershocks (adds the effect of recent earthquakes) and Recurrence (time since the last big one).
«Explain it, Tremo» puts it in plain words (written by AI using only those numbers).

Daily activity (90 days) and the region's Gutenberg-Richter curve.
Weekly scanner (M4.5+ or M5+ in 7 days) and this week's summary: which regions of the world are more active than usual. M4.5+ is what happens often in active regions: high probabilities that are checked every week.
Public scoreboard and backtest: how often each model said what, and how often it happened, since 2010 (M4.5+ and M5+ in 7 days, M6+ in 30). «Skill vs. historical» compares each model with the Historical one, which is the yardstick: that is why its row says «Baseline» instead of a number. A probability forecast isn't «right» one at a time: what's measured is whether, across everything it said, about the expected amount happened. So the scoreboard says how many earthquakes were expected (the sum of the probabilities) and how many there were, and lists when it did shake with what had been said. With fewer than 30 earthquakes it doesn't compare models live (it would be noise); the backtest does.

Hit or luck? Some social media accounts «get earthquakes right» all over the world. In the search box type a country, a city or «world» (accents are optional; cities come from OpenStreetMap), choose a magnitude and a time window, and Tremo tells you how likely it is to happen without predicting anything, using the real earthquakes of the USGS catalog. A country is counted whole, with its real shape and nearby sea (10 years from M5, 5 years for M4.5 and 1 year for M4); a city, your location or a region, within a circle of the radius you choose (15 years). For example: there are about 140 M4.5+ earthquakes a week worldwide, so «there will be earthquakes in Chile, Peru and Japan this week» comes true almost every time. Below it, «Why do some accounts get it right so often?» explains it in three points.

Public predictions under the microscope: when someone announces an earthquake, Tremo records what they said, the window and the outcome (happened, failed or postponed) and works out how many hits they would have had by pure chance. It shows that «an earthquake somewhere large» is almost certain to come true without knowing anything.

Nobody can predict the day, place and magnitude of an earthquake: no method has managed it in blind tests. What does help is what Tremo does: honest probabilities and alerts that warn before the shaking.

10. Tremo Network and early warning

Winning seconds before the shaking takes early warning: detecting the P wave near the epicentre and alerting before the S wave travels far. Tremo adds two routes, both in Tremo Network (☰ menu → Tremo Network).

Official alerts: those of official systems (SASMEX in Mexico; JMA, CWA and China in Asia). Each source shows «In testing» (recorded, no alerts), «Warns» or «Off». They are only switched on with the issuer's permission.
Our own network: phones with the app (and web stations) that feel the P wave. When at least 5 sensors in 3 different areas agree, Tremo detects it. The alarm follows the same rule as every alert: only to those who would feel it (intensity III or more), before the S wave arrives and outside their quiet hours. To place the epicentre it uses when the wave reached each phone and also how strongly (the closest one feels it hardest). If, with few sensors, the computed epicentre falls outside the network, it waits for more sensors: that way it never exaggerates the magnitude. Today it is in test mode: compared against official catalogues on the public scoreboard (hits, false alarms, missed earthquakes, detection time) and it will only alert once that scoreboard backs it up.
How it works: the step-by-step explanation at the bottom of the page.

In the Android app, the sensor listens only while the phone is charging and still (so it doesn't drain the battery or raise false alarms when you move it). Turn it on in «Your phone» → Earthquake sensor.
Tap «Set up step by step»: Tremo walks you through each missing permission (notifications, full-screen alarm, sounding in «Do Not Disturb», no battery limit, the sensor and Android's Earthquake alerts), tells you what you'll see and what to tap, opens the setting and, when you come back, checks that it's on. Anything you skip stays on the list for later.
So other shaking isn't mistaken for an earthquake: the phone doesn't count while its screen is on (someone is using it); the server ignores phones that trigger too often, recognises a wave that is too slow (thunder, an explosion or a train move far slower than a seismic wave) and, to alert, requires at least 8 sensors on several internet networks, with the epicentre inside the network and matching magnitudes. Tested with simulated thunder: none gets through.
«Test the alarm» shows the native alarm on this phone; «Test from the server» sends it over the internet (try it with the app closed).
In the browser or on iPhone, «Station mode»: leave Tremo open, plugged in, on the floor or a sturdy table and don't move it. iPhone doesn't allow listening in the background: there the phone is an alert receiver.

The first time you open the app, the «Full protection» sheet gathers all those permissions. If you tapped «Not now», you'll find them later in Tremo Network and in My Tremo → Will alerts reach me?.

11. «It's shaking!»: people's reports

If you feel an earthquake, tap «It's shaking!» (in Tremo Network or in the app notification's quick actions). When many people in many places report it at the same time, those further away get a blue notice: «N people report an earthquake». It's complementary: it never replaces the official networks.

Because a button like this invites pranks, Tremo sets several barriers:

Only phones with the Tremo Network sensor that have been in the network for more than a day and have been seen at their place count. A new phone is told «your reports count from tomorrow».
The place and time are set by the server, not the phone: nobody can pretend to be in another city.
One report every 10 minutes per phone, and only a few per internet connection.
It takes at least 8 people, from 5 different connections and 3 places at least 10 km apart, within 2 minutes: one office or one whole neighbourhood of pranksters is not enough.
Even then, the notice only goes out if another source confirms it (the Tremo Network or an official alert). Today reports are in testing: they're counted and compared with the catalogues (hits and false ones on the scoreboard), but they don't alert.
The blue notice arrives only once, without a siren and saying «unconfirmed», only to people who would feel it: it's worked out from the location and magnitude of the source that confirmed it, with the same rule as every alert (and not to anyone within 40 km, who is already feeling it). A report in Chile never reaches Colombia; one in Quito reaches Bogotá only if it would be felt there.

Only tap «It's shaking!» if you really are feeling it. False reports don't produce notices and they are recorded.

12. The Android and iPhone app

The app is all of Tremo plus what only a phone can do. Download it from ☰ menu → Download the app.

Full-screen alarm: when a quake reaches your alarm (and with early warning), with the screen locked Tremo's alarm opens with the magnitude, distance, intensity, countdown (if the wave hasn't arrived yet), the three steps and the «I'm OK», «Open Tremo» and «Close» buttons. It sounds even with the phone on silent or in «Do Not Disturb» if you granted that permission. For official networks' quakes, from version 1.0.8.
Quick access in notifications: a pinned notification with SOS, It's shaking! and Map always at hand. It is silent. To minimise it, long-press it and choose silence or minimise (depending on your Android); to remove it, turn off «Quick access in notifications» in My Tremo → Account.
Tremo Network sensor: listens while charging and comes back on its own after a restart.
Notification channels: «Earthquake alerts» (with siren), «Earthquakes you might feel» (the notice with the details: it pops up at the top of the screen, with a normal sound and no siren), «Earthquakes during quiet hours» and «People's reports». You can adjust each one in Android settings.
Tremo Plus inside the app is bought through Google Play or Apple.

Alerts, the map, SOS and the course are always free, on the web and in the app. The free app shows discreet ads: a banner at the bottom and, now and then, a full-screen one when you change screens (at most one every 5 minutes and 5 a day). Never in SOS, during an alert or over an open window, and the full-screen one never right after you come back to the app, in the half hour after an alert, or on your first day. With Tremo Plus, none.

13. Emergency (SOS)

The red SOS button in the top bar opens everything you need in an emergency. It works offline.

I'm OK and I need help: prepare a message with your location for WhatsApp or SMS.
During an earthquake: Drop, Cover and Hold on, with an explanation.
Your country's emergency numbers, with a call button.
Share my location, SOS whistle and SOS light.
My family: save their numbers to call or text them in one tap.
My emergency kit: the checklist to tick off what you already have.
After the earthquake: what to check, gas, damage and aftershocks.

I'm trapped opens trapped mode: a distress alarm that keeps sounding even when the screen turns off, SOS with the flash (on Android with Chrome; otherwise the screen acts as a light), an SMS with my location (texts often get through when calls don't; GPS works without internet) and advice to stay calm. It also opens from the Tremo icon's shortcut.

Fill in «My family» and «My emergency kit» today, calmly. In an emergency there's no time.

14. Learn: the course

The course comes from the book «Maestría Sísmica»: 69 short lessons in 12 units, from how the Earth works to how to prepare your family. Anyone can view the levels; doing the lessons takes a free account (so your progress is never lost).

Each lesson ends with questions: you earn points (XP), go up levels and keep your day streak.
Today's goal and a review of what you found hardest.
Unit quiz: 6 questions; 5 correct opens the next unit.
Final exam: 20 questions; with 80 % or more you get a verifiable diploma with its code (anyone can check it at its link).
24 badges for what you achieve.

You also earn points for things that protect you: turning on alerts, adding a place, preparing your kit and your family, running a drill, reporting what you felt or inviting someone.

15. Community

Talk with people in your country about what's happening. It takes a free account (accounts keep spam and abuse out).

Rooms by country: you join yours and can visit another country's.
Tap someone to see their profile, send a friend request, report or block. Private messages are only possible between friends.
Emojis, photos and voice notes: with 😊 pick an emoji, with 📷 send a photo and with 🎤 record a voice note of up to one minute, like on WhatsApp (in the Android app, voice notes arrive with version 1.0.6).
Private chat with your friends: once someone accepts your friend request, you can write to each other privately (open it with the friends button —a person with a «+», next to the room— or from their profile) with the same bar: emojis, photos and voice notes, which are also deleted after 30 minutes. If you block someone, they can no longer write to you or send you files.
Photos and audio are compressed on your phone (a photo ends up under 150 KB and without the GPS location photos carry), never go through Tremo's server and delete themselves after 30 minutes: each shows its countdown ⏳ and then «File deleted». If someone reports the message and it is hidden, the file is deleted at once.
If you lose signal, your text message waits and goes out by itself when the connection returns.
Rules: respect, no spam or personal data, and no rumours or «predictions»: official sources only. Moderators review every report.

16. Articles

In ☰ menu → Articles you'll find guides and explanations about earthquakes, alerts and preparedness, in English and Spanish. Each article has images, frequently asked questions, sometimes a selected video, and related articles. They're written by Gemini, Google's AI (their version in the other language too), and reviewed before publishing. The list shows the first 12 and «See all» the rest, like Tremo's other long lists.

17. Your account and progress

An account is free and optional: without one you have alerts, places, the map, the lab, SOS and articles. With one you also get the community, «Ask Tremo», the course, points and your settings on all your devices.

Sign in from My Tremo with email and password, Google or Facebook. When you register with email you get a link to confirm it.
Your profile: nickname, photo (or a Tremo or an emoji as avatar), «About you» and whether your profile is public (at /me/your-nickname).
Preferences: theme (automatic, light or dark), units, your country, lite mode, anonymous statistics and the app's quick access.
My data: export, import or delete everything on this device; and «Delete my account and everything I wrote».
Forgot your password? «Forgot your password?» sends you a link (valid for 1 hour).

In Progress you see your lessons, your «I felt it» reports, the alerts received and this device's alert history.

18. Tremo Plus

Tremo Plus is a single payment, forever (no subscription) that removes the ads and keeps Tremo going. It stays on your account: buy it on the web and it works in the app, and vice versa.

No ads in the app (or on the web, when you're signed in).
A ⭐ Plus badge on your profile and 3 exclusive Tremos for your avatar.
Ask Tremo: 120 questions a day instead of 40.
First to try what's new: the widget, the watch and native trapped mode are on their way, and you'll get them first.

Sign in to your account: Plus lives there and follows you to all your devices.
Tap «Pay with Mercado Pago» or «Buy with PayPal», pay and come back to Tremo. In the app, Plus is bought with Google Play or your Apple ID.
Have a coupon? Redeem it on this same page: a free Plus coupon activates it at once and a discount coupon lowers the price on the buttons.
Tremo verifies every payment with whoever collected it. If you were charged and it didn't activate, write to us from Contact.

Nobody misses alerts for not paying: alerts, the map, SOS, the course and history are always free.

19. If something goes wrong

Alerts don't reach me with the app closed.

Open My Tremo → Will alerts reach me? and fix whatever is red. Then tap «Test» and close the app: it should arrive within seconds. On Android, also check that Tremo has no battery limit and that the «Earthquake alerts» channel is on.

The alarm doesn't sound with the phone on silent.

In the app, grant «Sound in Do Not Disturb» (Tremo Network → Set up step by step). On the web, the browser can't override the phone's silent mode: that's what the app is for.

The dot in the top bar is amber or red.

Amber: an official network is slow to respond and you see the last valid data. Red: there's no internet; you see the last download. It fixes itself when the connection returns.

I see a screen saying «One moment, please…».

It's the server's firewall checking the connection. Wait a few seconds or reload; if it keeps happening, write to us from Contact.

Tremo looks old after an update.

Tremo updates itself the next time you leave the page or the app (never with an alert open). To force it, close it and open it again.

The map doesn't move with one finger.

Inside the page it moves with two fingers, so you can keep scrolling. Tap full screen and one finger is enough.

Does my location leave my phone?

To show you earthquakes, no: it's computed on your phone. If you turn on alerts with the app closed, the server stores only your places' coordinates to decide whom to alert (and, if you use the Tremo Network sensor, its approximate location). Turning off alerts deletes your places; the sensor's location is deleted automatically 60 days after you turn it off.

Something else? Write to us from Contact (☰ menu). We read every message. About lists the data sources and how Tremo works.

20. Frequently asked questions

Can Tremo predict earthquakes?

No. Nobody can. Tremo alerts you to earthquakes that already happened (and, with early warning, to their strong wave before it arrives) and the lab gives probabilities, publishing its hits and misses.

Why did I get the alert after I felt the earthquake?

If you're close to the epicentre, the strong wave arrives within seconds, before any network can publish it. The further away you are, the more head start. The Tremo Network and official early warnings aim to win those seconds.

Why wasn't I alerted to an earthquake that was on the news?

Because at your places it wouldn't have been felt at the intensity you chose. To hear about all the big ones, turn on «Major earthquakes worldwide» or use manual mode.

Does it work everywhere, even in the most remote places?

Yes: alerts, the map, the lab and SOS work anywhere on the planet, and Tremo works out what you would feel at any place. What changes is the network watching each area. Earthquakes of magnitude 4.5 or more are published from the whole planet, even mid-ocean, though they take longer (about 40 minutes median). Where networks are dense (Colombia, Europe, the United States, Japan, Chile…) small ones arrive too, and sooner; in Colombia the SGC publishes M4+ quakes in about 8 minutes. Official early warning exists in Mexico, Japan, Taiwan and China, and the Tremo Network works wherever there are phones with the sensor. Receiving alerts needs internet; SOS works without it.

What happens if an official network goes down?

Tremo doesn't depend on just one: it reads 21 official sources at once (18 national networks, EMSC, the USGS and GFZ). If a country's network goes down, like the SGC, EMSC, the USGS and GFZ continue, though only with the larger quakes and later; those late notices reach you as information, silently. If a source is slow, the dot in the top bar turns amber.

Will I get an alert for an earthquake in another country?

Only if you would feel it where you are: the rule is the intensity at your places, not the border. An earthquake in Chile doesn't ring in Colombia; if «Major earthquakes worldwide» is on, a distant M7 reaches you as information, silently. The same goes for the Tremo Network and people's reports.

What do the Roman numerals mean?

They're the Mercalli intensity: what is felt at a place. II is barely noticed, III is felt indoors, V is felt by nearly everyone and objects fall, VII or more causes damage.

Why did an earthquake's magnitude change?

The first data are «Automatic». When a seismologist reviews them, the magnitude and location may be adjusted and the earthquake becomes «Reviewed».

Does Tremo use a lot of battery?

No. The app doesn't use GPS in the background and the Tremo Network sensor only listens while the phone is charging.

Is it free?

Yes: alerts, the map, SOS, the course and history are always free. Tremo Plus is optional and removes the ads.

What languages is it in?

The app, in 14 languages. Lessons, articles and this guide, in English and Spanish.