3-D tomographic P- and S-wave seismic velocity model of the Santorini-Kolumbo Volcanic system (MGL1521, 2015)

This data set consists of a 3-D tomographic model of the P- and S-wave seismic velocity structure of the upper 15 km of the crust of Santorini-Kolumbo Volcanic system and the surrounding region. The model was derived from both passive and active-source data acquired during the PROTEUS 3-D seismic tomography experiment conducted during Langseth cruise MGL1521 in 2015. The model and results are described in Hufstetler et al. (2025). The data was collected using a dense amphibious array of >14,300 marine sound sources from a 6,600 cubic inch 36-component air gun array towed at 12-m depth that were recorded on 156 short-period marine and land seismometers, covering an area 120 km by 45 km. Average shot spacing was ~150 m along ENE-WSW oriented shot lines spaced at 1–2-km intervals and included shot-receiver offsets up to ~115 km. The data also included 37 mid-crustal earthquakes that occurred in this region during the experiment and were recorded on the same seismometers. Additionally, 26 events are from the temporary networks CYCNET and EGELADOS that were deployed in the southern Aegean to study the seismotectonic behavior of the Hellenic Subduction Zone (Brüstle et al., 2012). The network CYCNET covered the central Hellenic Volcanic Arc from September 2002 to September 2005, while the EGELADOS network was deployed from October 2005 to April 2007 covering the entire southern Hellenic Subduction Zone (Bohnhoff et al., 2004; Friederich & Meier, 2008). A three-dimensional, iterative tomographic technique (Toomey et al., 1994) was used to invert over 200,000 Pg refraction arrival times, 1515 first-arriving earthquake P-waves, and 1435 earthquake S-waves arrivals to constrain isotropic slowness. There are 4 NetCDF velocity model files, each formatted with UTM coordinates (UTM zone 35N) and with velocities on a grid that is spaced 400 m horizontally and vertically. The files contain longitude, latitude, depth (km), UTM easting (m), UTM northing (m) and either P- or S-wave velocity (km/s). The two files with file names labeled "masked" contain velocity values only where sufficient ray coverage exists, while the two files labeled "unmasked" contain all velocity values in the modeled region regardless of coverage. The model is centered at latitude 36.4042 and longitude 25.3971 with a rotation of 25.5 degrees counterclockwise about this point. The corners of the model are: Top-left (Northwest): (36.9, 24.6); Top-right (Northeast): (36.9, 26.2); Bottom-left (Southwest): (35.9, 24.6); Bottom-right (Southeast): (35.9, 26.2). This data set was generated as part of the project called Crustal magma plumbing of the Santorini volcanic system. Funding was provided by NSF award OCE14-59794.