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Special Data Sets

Alternate Catalogs

SCSN Double Difference Catalogs

Starting in 2026, the SCSN began producing timely earthquake catalogs with locations refined using a technique called hypocenter double-difference relocation in response to notable sequences and swarms in Southern California. Rather than relying solely on the absolute travel time of seismic waves through the Earth’s crust, double-difference methods determine earthquake locations by comparing pairs of nearby earthquakes recorded at the same seismic stations. The result is a much more precise picture of where earthquakes are actually occurring, often revealing fine-scale fault structures and clustering patterns that are not visible in standard catalogs.

These response catalogs are generated using the same procedure as the Hauksson relocated catalog. While they are available more quickly, they also receive less detailed adjustment and quality control. The software pipeline uses the hypoDD algorithm with a 3-D velocity model, and the initial starting dataset may include hypocenters that have not been analyst reviewed.
Formats and datasets provided below.

 

 

Figure 3. 3d map of 2026/08/23 M4.0 Coso Junction Sequence

 

References:

Hauksson, E. and W. Yang, and P.M. Shearer, "Waveform Relocated Earthquake Catalog for Southern California (1981 to 2011)"; Bull. Seismol. Soc. Am., Vol. 102, No. 5, pp.2239-2244, October 2012, doi: 10.1785/0120120010

Downloads:

Format and catalog information
2026/01/19 M4.9 Indio Sequence Catalog file (please save as download)
2026/05/10 M3.6 Brawley Swarm Catalog file (please save as download)
2026/07/13 M4.3 Johannesburg Sequence Catalog file (please save as download)
2026/08/23 M4.0 Coso Junction Catalog file (please save as download)