ComCat

ComCat, short for Comprehensive Catalog, is the public earthquake catalog maintained by the United States Geological Survey (USGS) as part of its Earthquake Hazards Program. It provides a centralized, openly accessible source of information on earthquakes worldwide, including event time, location, depth, magnitude, and related metadata.

Data in ComCat are compiled from seismic networks and processing centers and are updated in near real time as new observations arrive. The catalog supports programmatic access through a RESTful API, enabling users to search for events within a specified time window or geographic region, within a magnitude range, or by depth. API responses are available in JSON, GeoJSON, and CSV formats for easy integration into applications and research workflows.

Event records include fields such as event ID, time (UTC), latitude and longitude, depth, magnitude and magnitude type, place description, and status. Some events carry multiple magnitude estimates from different computation methods, and data may be revised as more information becomes available.

Applications of ComCat include academic research, hazard assessment and modeling, emergency management, journalism, and education. It is widely used by scientists, government agencies, media outlets, and developers to access standardized, publicly available earthquake data.

Limitations include potential delays in updating very small events and subsequent magnitude or depth revisions as analyses are refined. Users are advised to verify critical information against multiple sources and consider data quality flags provided in records.