Using glaciers to identify, monitor and predict volcanic activity

Globally, ~250 Holocene active volcanoes are either glacier-clad or have glaciers in close proximity. The presence of glaciers on a volcano sometimes masks evidence of volcanic activity and therefore makes direct observations of volcanic activity more challenging if compared to an ‘ice-free’ volcano. However, it is also possible that glaciers can provide indirect information about the activity of the volcanoes on which they sit. With this in mind, the overall aim of this thesis is to assess the degree to which volcanically triggered impacts on glaciers can be observed from optical satellite imagery, and to consider whether these impacts can be used to help identify, monitor and predict volcanic activity. To achieve this, volcanically triggered changes in glacier surface morphology and glacier surface velocity are studied on ice-clad volcanoes using optical satellite images. Approximately 1400 optical satellite images are investigated from key, well-documented eruptions from 1972 to 2015 (i.e., during the satellite remote sensing era) and around the globe. To investigate volcanically triggered changes in surface velocity, glacier velocimetry is performed on Cone Glacier (Mount Veniaminof, Alaska) using 99 Sentinel-2 band 8 images (near-infrared, central wavelength: 842 nm) covering two volcanically active periods, one from September to December 2018 and one in March/April 2021. This approach includes the extraction of velocities along a profile line (following an inferred ice flowline), the generation of time-series velocities, and the calculation of velocity difference maps. The extensive analysis of optical satellite images around the globe shows that the most common observable volcanic impact on glacier morphology (for both thick and thin ice-masses) is ice cauldron and opening formation, often (but not exclusively) associated with concentric crevassing. Other observable volcanic impacts on glacier morphology include ice bulging and fracturing due to subglacial dome growth, localized crevassing due to supraglacial lava flows and widespread glacier crevassing, presumably, due to meltwater-triggered glacier acceleration and advance. Glacier velocimetry results from Cone Glacier show faster glacier surface velocities ~10 months prior to the 2018 volcanically active period and ~2 months prior to the 2021 volcanically active period. Also, an amplified seasonal cycle of faster-than-usual surface velocities in the summer and slower-than-usual surface velocities in the winter is observed during both years with an eruption. Volcanically triggered meltwater is considered as a cause of changing the subglacial drainage at Cone Glacier and is therefore argued as a potential cause of the observed surface velocity changes. The wider applicability of the results to other temperate and polythermal glaciers affected by volcanic activity is discussed. In all, this thesis works towards a deeper understanding of volcanic impacts on glacier morphology and dynamics, elaborates main limitations of using optical satellite images to study ice-clad volcanoes and provides advice for best practice for monitoring glaciers in volcanically active areas

Geomorphometry 2020. Conference Proceedings

Geomorphometry is the science of quantitative land surface analysis. It gathers various mathematical, statistical and image processing techniques to quantify morphological, hydrological, ecological and other aspects of a land surface. Common synonyms for geomorphometry are geomorphological analysis, terrain morphometry or terrain analysis and land surface analysis. The typical input to geomorphometric analysis is a square-grid representation of the land surface: a digital elevation (or land surface) model. The first Geomorphometry conference dates back to 2009 and it took place in Zürich, Switzerland. Subsequent events were in Redlands (California), Nánjīng (China), Poznan (Poland) and Boulder (Colorado), at about two years intervals. The International Society for Geomorphometry (ISG) and the Organizing Committee scheduled the sixth Geomorphometry conference in Perugia, Italy, June 2020. Worldwide safety measures dictated the event could not be held in presence, and we excluded the possibility to hold the conference remotely. Thus, we postponed the event by one year - it will be organized in June 2021, in Perugia, hosted by the Research Institute for Geo-Hydrological Protection of the Italian National Research Council (CNR IRPI) and the Department of Physics and Geology of the University of Perugia. One of the reasons why we postponed the conference, instead of canceling, was the encouraging number of submitted abstracts. Abstracts are actually short papers consisting of four pages, including figures and references, and they were peer-reviewed by the Scientific Committee of the conference. This book is a collection of the contributions revised by the authors after peer review. We grouped them in seven classes, as follows: • Data and methods (13 abstracts) • Geoheritage (6 abstracts) • Glacial processes (4 abstracts) • LIDAR and high resolution data (8 abstracts) • Morphotectonics (8 abstracts) • Natural hazards (12 abstracts) • Soil erosion and fluvial processes (16 abstracts) The 67 abstracts represent 80% of the initial contributions. The remaining ones were either not accepted after peer review or withdrawn by their Authors. Most of the contributions contain original material, and an extended version of a subset of them will be included in a special issue of a regular journal publication