2025 Santorini–Amorgos NLL-SSST-coherence high-precision relocated earthquake catalog

Relocated earthquake catalog and plots of NLL-SSST-coherence earthquake relocations of 4088 earthquakes for the period 2024/01/01 to 2025/03/14 for the Santorini-Amorgos region where the January-February 2025 seismic crisis took place. Phase arrival data taken from the bulletins from the Geophysics Department of Aristotle University of Thessaloniki (doi:10.7914/SN/HT) as well as the National Observatory of Athens (doi:10.7914/SN/HL) can be found in the phase_observations.zip file, formatted for NLL.

NLL-SSST-coherence combines source-specific, station traveltime corrections (SSST) and stacking of probabilistic locations for nearby events based on inter-event waveform coherence (Lomax and Savvaidis, 2022; Lomax and Henry, 2023). The seismic velocity model used for the location and relocation procedures is taken from (Papadimitriou et al., 2015).

The catalog is provided in three different formats (.csv, QuakeML and simple txt file). Catalog data columns are as follows:

·       event_id: Sequential event ID number

·       latitude: Latitude of relocated epicenter

·       longitude: Longitude of relocated epicenter

·       depth: Depth of relocated earthquake

·       magnitude: Earthquake magnitude

·       magnitude_type: Earthquake magnitude type

·       Temporal origin parameters (year, month, day, hour, minute, seconds)

·       RMS: RMS of the travel time residuals of the arrivals used for the origin computation.

·       Nphases: Number of defining phases, i.e., phase observations that were actually used for computing the origin

·       AzGap: Azimuthal Gap

·       dist_sta: Epicentral distance of station closest to the epicenter

·       ErrH: Horizontal error

·       ErrZ: Depth error

Plot shows:

Evolution of seismicity in the Santorini – Amorgos region of the NLL-SSST-coherence relocated earthquakes from 2024/01/01 to 2025/03/13. Each subplot pertains to a specific time period, as noted in each header. Symbol sizes are proportional to earthquake magnitudes, while plot colors correspond to earthquake focal depths, as shown in the color bar.

Auxiliary plot data:

The GMT mapping software (Wessel et al., 2019) was used for figure preparation. 

 Topography/bathymetry grid data obtained from GeoMapapp (https://www.geomapapp.org/)