Workflow

Using the coordinates (latitude and longitude) and the UTC time of a local event as input, TieBeNN processes seismic event locations through the following stages:

1. Waveform data fetching: A catalog of stations around the epicenter is produced. Then, waveform data in miniSEED format are retrieved using an ObsPy client on FDSN servers or from a SDS directory structure.

2. Waveform data preprocessing: Empty channels are removed, masked channels are split, and data are detrended and bandpass filtered. Optionally, stations within 100 km from the epicenter are denoised using the DeepDenoiser model (Zhu et al. 2019).

3. Phase picking: P- and S-phases (first arrivals) are detected using phase-picking models (either EQTransformer or PhaseNet, available in the SeisBench toolbox.

4. Phase association: Detected picks are passed through phase associators to discard possible false detections. TieBeNN supports PyOcto and GaMMA.

5. Export outputs: Event-associated phase picks are exported to CSV files, including station coordinates, arrival times, pick probabilities, and signal-to-noise ratios. NonLinLoc input files are generated. Optionally, waveform and pick figures per station, as well as phase association plots, are produced.

6. Probabilistic hypocenter estimation: The generated files are used by NonLinLoc for hypocenter estimation. Optionally, the following figures are created:

1. Epicenter and stations on a map

2. Waveforms with picks sorted by epicentral distance

3. location confidence ellipsoid.

7. Location quality assessment: Location metrics are gathered to compute the Location Quality Score (LQS) and to generate a visualization. A description of this metric should be available in a manuscript, currently in preparation

Note

TieBeNN loops through this process until the minimum required detections within a given epicentral distance are obtained. If not, the search radius is gradually expanded. If phase picks are insufficient within 200 km, the run ends with an unsuccessful event location.