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Phase Associator Comparison for Small Scale Seismic Networks

Phase association, linking picks to an earthquake, is a critical step in earthquake location analysis, both in real-time and in post-processing studies. A widely used real-time earthquake associator is the Earthworm module known as binder (Johnson, 1997). Binder employs a grid search based algorithm for earthquake association using only P arrivals. Because S-wave arrivals are included only after the nucleation of the event using P arrivals, the performance of Binder is limited by the need for clear P arrivals. This constraint is particularly disadvantageous for induced seismic monitoring, where P picks are often sparse due to the low amplitude signal of smaller magnitude earthquakes.. In contrast, the post-processing algorithm known as GaMMA uses a new Gaussian Mixture Model approach to phase association using both P and S arrivals. PyOcto, another promising new associator, employs an Oct Tree sorting algorithm that uses both P and S arrivals.

In this study, we compare the results and parameter adjustments of the three association approaches for small scale monitoring arrays (5x5km) as well as explore a new version of binder, named SBinder, that also nucleates on S arrivals. We use analyst-curated catalogs from these small-scale arrays (8-12 stations) as a benchmark, complete with combined sets of picks from a STA/LTA picker, a filter-based picker, and a custom-trained PhaseNet model. We test and present the performance of these associators against these pick sets.

Initial results show that GaMMA performs better with tuned PhaseNet picks than with phase arrivals from traditional pickers. We find that GaMMA generates new events that were previously missed in the curated catalog when used in tandem with PhaseNet picks, but additional tuning was required in the location phase to prevent the inclusion of a significant number of false detections.

Session: Network Seismology: Recent Developments, Challenges and Lessons Learned [Poster]

Type: Poster

Room: Exhibit Hall A+B

Date: 4/15/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Paul Friberg

Student Presenter: No

Invited Presentation: 

Poster Number: 15

Additional Authors