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tremor@ideaheron.comTremor Q&A
Where does the earthquake data come from?
Tremor aggregates four authoritative public feeds: the U.S. Geological Survey (USGS), the European-Mediterranean Seismological Centre (EMSC), the Japan Meteorological Agency (JMA), and GeoNet (New Zealand). Events from different sources are merged and deduplicated.
How recent is the data?
Tremor checks for published feed updates about once a minute while the main app is open. The earthquake catalog covers the latest seven days, although upstream sources can report new or revised events with a delay.
Why don't I see very small earthquakes?
Tremor shows events at or above your magnitude filter, with a minimum threshold of M1.0. Adjust the magnitude filter to see more or fewer events. Some geographic regions may have fewer recorded events due to limited sensor coverage or data availability.
Why is there an incorrect earthquake on the map?
Seismic networks may publish events automatically before a human reviews them, so early estimates of magnitude or location can change and an event may be withdrawn. Tremor applies corrections and confirmed withdrawals after they reach its published catalog. Some withdrawals require repeated source checks and may not disappear on the next refresh.
How do I create earthquake alerts?
Go to Filters and choose a region, minimum magnitude, and optionally, depth. Then scroll down to My Alerts and select Create Alert from Current Filters. For local alerts, choose "Near Me"; this saves a fixed 150 km area around your location when you create the alert and does not move automatically afterward. For significant world events, choose "Worldwide" and set the magnitude filter to a value like 6.0. Since there can be a delay in reporting, alerts may not be triggered immediately for very recent events. Therefore, Tremor is not an earthquake early-warning or emergency-notification service.
Why didn't I receive an alert?
Creating an alert requires notification permission. If you dismissed the permission screen during the first launch of the app, you can go to your device's Notification settings and look for Tremor to grant permissions. Only newly reported earthquakes that arrive after an alert takes effect are eligible; corrections, older events, and events already known when the alert was created do not trigger alerts retroactively. Delivery of alerts can be affected by Internet connectivity, Focus/Do Not Disturb settings, or system notification settings.
Which devices are supported?
Tremor runs on iPads with iPadOS 26 or later and Macs with macOS 26 or later.