Reading a Catalog

The command requake read_catalog imports an earthquake catalog into Requake’s output database, ready for scanning. It can fetch events from an FDSN event web service or read them from a local file.

Sources

FDSN web service

If no file is given on the command line:

requake read_catalog

Requake downloads the catalog from the FDSN event service configured in the configuration file (catalog_fdsn_event_url and, optionally, up to three additional URLs for different time intervals). The selection is narrowed by the geographic, depth, magnitude, and time filters defined in the same configuration file.

Local file

A local catalog file can be provided directly:

requake read_catalog CATALOG_FILE

Requake auto-detects the format from the file content, supporting:

  • QuakeML — the standard XML-based seismological catalog format.

  • FDSN text — the plain-text format returned by FDSN event web services (one line per event, # for comments).

  • CSV — comma-separated values. Requake guesses column names automatically by matching the CSV header against common field names (e.g., time, lat, lon, depth, magnitude) and their common variants (origin_time, latitude, depth_km, mag, etc.). If no event ID column is present, Requake generates one automatically from the origin time, in the form reqk + year + six-letter suffix (e.g., reqk2023ltrqbk).

Note

If Requake cannot parse your CSV file — for example because the columns are in an unexpected format or contain mixed data types — don’t despair! I also wrote SeisCat, a friendly companion tool for reading, filtering, plotting, and exporting earthquake catalogs. You can use it to inspect your catalog visually, clean it up, and export a tidy CSV that Requake will happily digest. I warmly encourage you to give it a try 😊.

When reading from a local file, the catalog is still filtered using the geographic, depth, magnitude, and time criteria from the configuration file. To bypass filtering, set the relevant bounds wide enough to include all events.

Filtering and deduplication

Regardless of the source, the catalog is filtered using the following configuration parameters:

  • catalog_start_time / catalog_end_time (+ optional intervals 1–3)

  • catalog_lat_min / catalog_lat_max

  • catalog_lon_min / catalog_lon_max

  • catalog_depth_min / catalog_depth_max

  • catalog_mag_min / catalog_mag_max

Duplicate events (same event ID) are automatically removed, and the catalog is sorted by origin time before being written to the database.

Appending to an existing catalog

Use --append to add new events to an already stored catalog:

requake read_catalog --append

Existing events are kept; only new events (by event ID) are added.

Output

The catalog is stored in the catalog table of the output database. Once the catalog is ready, proceed with the catalog scan.

Minimal catalog: origin times only

Requake can work with a minimal catalog containing nothing but origin times — no location, magnitude, or even event ID is strictly required.

If an event has no latitude or longitude, it is placed at the same location as the configured station (catalog_trace_id) during the catalog scan. This is useful for analysing lists of unlocated events, such as template-matching detections or manually picked arrival times.