Figure 1. Topographic relief map of the northern Santorini volcanic field.

A red star icon shows the location of the center of inflation deduced from InSAR data¹⁵, the white star icon shows the location of the Kallisti Limnes CO₂ pools. The onshore Kolumbo fault is indicated by a dashed red line, which along with the Kolumbo line, describes the northeast portion of the Christianna-Santorini-Kolumbo (CSK) tectonic line. The inset box shows a detailed view from the southwest of the caldera slope bathymetry around the study site; submersible vehicle track lines are indicated as red, orange, and yellow lines, corresponding to the first and second AUV dives, and the HOV dive, respectively. Sonar and vehicle position data was processed using MB—System Revision 1.15 (including source code derived from other sources, described at http://www.ldeo.columbia.edu/res/pi/MB-System/html/mbsystem_copyright.html), GMT-4.5.7, MATLAB, and Fledermaus version 7.4.1 c software.