Support
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Tremor 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?
Feeds refresh continuously while the app is open. Tremor retains a rolling seven-day window of events. While Tremor aims to provide real-time information, some data feeds can have a slight delay in their reporting.
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 publish events automatically, before a human reviews them. Early estimates of magnitude or location are sometimes wrong, and an event may occasionally be revised or withdrawn entirely — usually within minutes, sometimes a few hours. When a source corrects or removes an event, Tremor picks up the change automatically on its next refresh. To force an immediate update, tap Refresh Cache in Settings.
How do alerts work?
You can turn on notifications for significant world events (M6.0 and above, anywhere) or for quakes near you by going to Settings. Both are off by default. Enabling them asks for the relevant permissions, and you can turn them off anytime.
Why didn't I receive an alert?
Alerts are only sent for events that meet the criteria you've set in the app's settings. Be sure Tremor is running in the background on your device and Background App Refresh (in iOS settings) is turned on. Tremor uses on-device notifications instead of push notifications to avoid having to store your private location data on a server. Note that alerts are not sent if your device is in Low Power Mode.
Which devices are supported?
Tremor runs on iPad (iOS 26.0+) and Mac (Apple Silicon, macOS 26+).