Area Estimates of Low Temperature Venting at Selected Sites Within the ASHES Vent Field on Axial Seamount Through ImageJ Analysis of 2018 and 2019 Video

Abstract:

The goal of this study is to estimate the areal extent of low temperature venting by digitizing the distribution of the cracks in selected sites within the ASHES vent field. The ASHES vent field is region of low and high temperature venting located within the caldera of Axial Seamount near the Juan de Fuca Ridge off the coast of Oregon. A series of selected images from video data collected in 2018 and 2019 were combined into photo collages of the selected sites to identify cracks with active venting. This method assumes that image distortions are small in the center of the video frames and that active venting leaves visible anhydrite or iron deposits. Color-based filters were created by using ImageJ color thresholding filters which allowed for areas to be selected based on color. Internal evidence was used to scale the area. For each area, we compare the video-based area estimates with acoustic imaging estimates of low temperature venting distributions to assess whether the estimates are mutually consistent. We also use in situ temperature measurements collected in 2018 and 2019 to assess the relevance of the color-based filters.