Study region (see box in upper right inset), comprising the Vanuatu archipelago and the main island of New Caledonia (Grande Terre). Black square: location of IS22, New Caledonia. Red triangles: location of the most active volcanoes; names on right. Grey dashed lines: great-circle distances and azimuths from IS22 to each volcano (annotated). Lower-right: IS22 array geometry in Cartesian coordinates (km).